The Diagnosis of Lymphoproliferative Diseases

The Diagnosis of Lymphoproliferative Diseases

The Diagnosis of Lymphoproliferative Diseases Kevin C. Gatter Head of Department & Professor of Pathology Nuffield Department of Clinical Laboratory Science Oxford University, Oxford, UK

Georges Delsol Professor of Pathology Laboratory of Pathology, Hôpital Purpan Centre Hôpitalier Universitaire University of Toulouse Toulouse, France

Roger A. Warnke Professor of Pathology Stanford University School of Medicine Stanford, CA, USA

Francesco Pezzella Professor of Pathology Nuffield Department of Clinical Laboratory Science Oxford University, Oxford, UK

S E C O N D E DI T I ON

A John Wiley & Sons, Ltd., Publication

This edition first published 2012, © 2012 by Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella Blackwell Publishing was acquired by John Wiley & Sons in February 2007. Blackwell’s publishing program has been merged with Wiley’s global Scientific, Technical and Medical business to form Wiley-Blackwell. Registered office: John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial offices: 9600 Garsington Road, Oxford, OX4 2DQ, UK The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK 111 River Street, Hoboken, NJ 07030–5774, USA For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com/wiley-blackwell The right of the author to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. The contents of this work are intended to further general scientific research, understanding, and discussion only and are not intended and should not be relied upon as recommending or promoting a specific method, diagnosis, or treatment by physicians for any particular patient. The publisher and the author make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of fitness for a particular purpose. In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of medicines, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each medicine, equipment, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions. Readers should consult with a specialist where appropriate. The fact that an organization or Website is referred to in this work as a citation and/or a potential source of further information does not mean that the author or the publisher endorses the information the organization or Website may provide or recommendations it may make. Further, readers should be aware that Internet Websites listed in this work may have changed or disappeared between when this work was written and when it is read. No warranty may be created or extended by any promotional statements for this work. Neither the publisher nor the author shall be liable for any damages arising herefrom. Library of Congress Cataloging-in-Publication Data The diagnosis of lymphoproliferative diseases / Kevin C. Gatter ... [et al.]. – 2nd ed. p. ; cm. Rev. ed. of: The diagnosis of lymphoproliferative diseases / Kevin Gatter, Georges Delsol. 2002. Includes bibliographical references and index. ISBN-13: 978-1-4051-7014-7 (hardcover : alk. paper) ISBN-10: 1-4051-7014-X (hardcover : alk. paper) ISBN-13: 978-1-119-97174-0 (ePDF) ISBN-13: 978-1-119-97177-1 (Wiley Online Library) [etc.] 1. Lymphoproliferative disorders–Diagnosis. I. Gatter, Kevin. II. Gatter, Kevin. Diagnosis of lymphoproliferative diseases. [DNLM: 1. Lymphoproliferative Disorders–diagnosis–Atlases. WH 17] RC646.2.D54 2011 616.99'373–dc23 2011015320 ISBN: 978-1-4051-7014-7 A catalogue record for this book is available from the British Library. This book is published in the following electronic formats: ePDF 9781119971740; Wiley Online Library 9781119971771; ePub 9781119971757; Mobi 9781119971764 Set in 9/12pt Meridien by Toppan Best-set Premedia Limited 1

2012

Contents

Preface, vi

18 Adult T-cell Lymphoma/Leukaemia, 169

Abbreviations, vii

19 Extranodal NK/T-cell Lymphomas: Nasal Type, 172 20 Enteropathy-associated T-cell Lymphoma, 178

1 General Introduction, 1

21 Hepatosplenic T-cell Lymphoma, 182

2 Reactive and Infective conditions, 20

22 Subcutaneous Panniculitis-like T-cell Lymphoma and Primary Cutaneous γ/δ T-cell Lymphoma, 185

3 An Introduction to Lymphoma Diagnosis, 59 4 B-cell Lymphoblastic Leukaemia/Lymphoma, 63 5 T-cell Lymphoblastic Lymphoma/Leukaemia, 69 6 B-cell Chronic Lymphocytic Leukaemia, 75 7 Splenic B-cell Marginal Zone Lymphoma, 81 8 Hairy Cell Leukaemia, 86 9 Lymphoplasmacytic Lymphoma, 92 10 Plasmacytoma/Myeloma, 96 11 Marginal Zone B-cell Lymphoma (Extranodal Malt and Nodal Types) and Extranodal Malt Lymphoma, 100 12 Follicular Lymphoma, 108 13 Mantle Cell Lymphoma, 121

23 Mycosis Fungoides/Sézary Syndrome, 189 24 Peripheral T-cell Lymphoma, 194 25 Angioimmunoblastic T-cell Lymphoma, 202 26 Anaplastic Large-cell Lymphoma, 208 27 Hodgkin Lymphoma, 220 28 Immunodeficiency-associated Lymphoproliferative Disorders, 242 29 Histiocytic Sarcoma, 249 30 Follicular Dendritic Cell Proliferations and Related Entities, 255 31 Langerhans Cell Histiocytosis, 261 32 Myeloid Leukaemias (Myeloid Sarcoma), 265

14 Diffuse Large B-cell Lymphoma, 134 15 Burkitt Lymphoma, 155

Index, 268

16 T-cell Prolymphocytic Leukaemia, 161 17 T-cell Large Granular Lymphocytic Leukaemia and Aggressive NK-cell Leukaemia, 164

v

Preface

As was the case for the first edition this the second comes as a companion to the recently revised WHO Classification of Tumours of Haematopoietic and Lymphoid (2008). Once again our aim is to guide pathologists through the practical stages of making an accurate diagnosis. We have updated the text and figures to incorporate all the new entities and to clarify and extend other sections especially the large chapter on reactive conditions. The authorship team has doubled to bring in wider experience and fresh thought. We hope pathologists will find this book helpful and use it side by side with the new WHO classification.

Acknowledgements Again we pay tribute to our departments and colleagues without whom it would have been impossible to gather the cases and find the time to put them together into a cohesive text. Once more our informatics production manager Robin Roberts-Gant has been a sterling assistant in collating text and figures ready for publication. We would also like to thank Wiley- Blackwell for taking on this second edition at a time when medical publishers are cutting back severely and for their high quality help and advice.

vi

Abbreviations

AILT ALCL ALL ALK AML ATLL CHL CLL DLBCL EATL EB/EBV EBER EMA FDC FISH FL HCL HL LP LCA LGL LPL MALT MCL MZL NHL NK NLPHL PCR PLL PTCL PTLD WHO

angioimmunoblastic T-cell lymphoma anaplastic large cell lymphoma acute lymphoblastic lymphoma/leukaemia anaplastic lymphoma kinase acute myeloid leukaemia adult T-cell lymphoma/leukaemia classical Hodgkin lymphoma chronic lymphocytic leukaemia diffuse large B-cell lymphoma enteropathy-associated T-cell lymphoma Epstein–Barr/Epstein–Barr virus Epstein–Barr virus RNA epithelial membrane antigen follicular dendritic cell fluorescence in situ hybridisation follicular lymphoma hairy cell leukaemia Hodgkin lymphoma lymphocyte predominant leucocyte common antigen large granular lymphocytic leukaemia lymphoplasmacytic lymphoma mucosa associated lymphoid tissue mantle cell lymphoma marginal zone lymphoma non-Hodgkin lymphoma natural killer nodular lymphocyte predominant Hodgkin lymphoma polymerase chain reaction prolymphocytic lymphoma peripheral T-cell lymphomas post-transplant lymphoproliferative disorder World Health Organization

vii

1

General Introduction

The biopsy The decision on whether or not to biopsy a lymph node or other tissue for a suspected haematological disease is taken by the clinician. In a good haematological oncology unit the pathologist will be involved in this decision, if only to provide technical advice. The correct biopsy optimally handled is very much in everyone’s best interests and is often crucial in reaching an accurate diagnosis. The old military adage of the six Ps (proper preparation prevents p*** poor performance) was never more apt. Clinical details of who, when and what are better placed in clinical books but a few practical comments may be appreciated.

Sutton’s law If a patient has significant lymphadenopathy associated with other signs and symptoms, do not mess about with skin, bone marrow smears or cytological preparations in the hope that it will save a biopsy. If patients are sick they need a diagnosis and the money is in the lymph node.

Can we manage with a needle biopsy – skinny or cutting? In the first edition of this work we said no. These techniques are marvellous in their place but no substitute for a lymph node biopsy when it can reasonably be obtained. It has become increasingly obvious as costs and clinical workloads soar worldwide that we are going to have to cope with needle biopsies more and more whether we like it or not. This means that we will need to rely increasingly on ancillary techniques to make diagnoses. We should, however, never forget that these are suboptimal specimens and be aware that we may have missed the true lesion.

Must we take out the whole node? Can’t you make do with a slice? Yes and no (well perhaps). Lymphoid diseases are often focal and surrounded by reactive changes and so easy to miss on smaller samples. Slices get crushed with resultant misleading artefacts. Go for the biggest node accessible. Cervical nodes are best and inguinal worst (due to the inevitable reactive changes). Take out the whole node and send to an alerted pathologist or experienced laboratory. It is much better to send a fresh node so that it can be dealt with promptly and optimally. This also allows material to be used for techniques that can be suboptimal on fixed material such as some molecular investigations. It also enables material to be taken for biobanking, which is becoming increasingly important with the current renewed interest in translational medical research. If the biopsy cannot be sent or processed that day, get the surgeon or lab technician to slice it like a boiled egg into fixative (plenty of). There is no better way that we know of ruining a lymph node than to ram it whole into a small pot. The capsule is immensely impervious to fixative, leaving the innards to rot rapidly. Take representative blocks, one per centimetre should easily suffice, send a piece to microbiology if infection is queried and freeze a piece in liquid nitrogen (it can be stored at −70°C later). The rest of the slices can be left in fixative while a diagnosis is being sought. Most hospitals keep this material for a month or so, allowing plenty of time to go back for more blocks if necessary.

Which fixative? Theses have been written on this and largely ignored. Ninety-nine per cent of the world uses formalin and shows

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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General Introduction

little evidence of changing. And if the steps above are taken, it is a good all-round reagent that is hard to better. All the other fixatives suggested to date (e.g. Bouin’s, B5, Duboscq– Brasil) are good in experienced hands but may compromise certain antibody stains and most molecular studies.

Immunocytochemistry If you are doing serious haematopathological diagnoses you will be using a lot of antibodies. So you might as well invest in an immunostaining machine (or two). Once done you will wonder how you coped without it. It is just like having a dishwasher at home. All the machines currently on the market work well. They differ in the degree to whether they are open or closed systems, as well as whether antigen retrieval is available on the machines, or whether it must be performed manually (see below). Closed systems are fine when the finances for immunostaining are no problem because all the reagents can be bought pre-packed from the manufacturer and used straight off the shelf. If every penny (cent or euro) counts (as in the cash-starved NHS in the UK), then completely open systems are best where individual reagents, including the detection reagents, can be bought at good prices or begged and borrowed and used according to local recipes. To our knowledge all machines are capable of following most techniques but, as with the fixatives above, most of the world has settled on one or other variation of immunoperoxidase staining. This gives excellent reliable results, and full details and technical back-up are available from a range of antibody companies. Recently introduced antigen retrieval techniques have been a revolution, so every laboratory needs a microwave and/or pressure cooker for manual methods as well as for certain staining platforms. Again all the reagents and advice necessary are available from the relevant commercial companies.

Which antibodies? In the early days of immunocytochemistry considerations of cost and labour led most pathologists to select reagents singly, according to the details of each case. Now that immunostaining is an accepted diagnostic technique and automated machines are available, there is little reason any longer to remain parsimonious. Link this with the current epidemic of medicolegal claims, and comprehensive panels of antibodies start to seem common sense. Ask yourself if you could justify in court missing a mantle cell lymphoma or a reactive node just because you thought a cyclin D1 or a bcl-2 immunostain was not warranted. Specific details of individual antibodies and how they are used and interpreted are discussed under the individual entities. Here, for reference purposes, are the antibodies that we use routinely. All refer to use on paraffin-embedded fixed

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material. The clone numbers given are those known to us as working antibodies. New and better reagents appear regularly and may be available from more than one producer, so it is worth looking around. Pre-treatments for optimal staining are constantly being updated. They differ from place to place, and change as new techniques are described and new reagents produced. It is worth each laboratory testing out a number of these for themselves for each new antibody introduced. Table 1.1 gives a differential diagnosis between lymphoma and non-haematopoietic tumours.

Monoclonal antibodies of diagnostic value in paraffin sections in the diagnosis of haematopoietic neoplasms The antibodies used for different antigens can be organised into panels for specific purposes or divided into those for first and subsequent runs of immunostaining according to personal preference. The importance of the panel approach is to ensure that an important diagnosis is not overlooked. Table 1.2, for example, gives some panels that we use in routinely diagnosing and classifying lymphomas.

Low-grade B-cell lymphoma CD20, CD79a, CD3, CD10, bcl-2 protein, κ and λ, cyclin D1, CD5, CD23, proliferation marker (Ki67 or equivalent). When a marginal zone lymphoma (MZL) of MALT (mucosaassociated lymphoid tissue) type, add a pancytokeratin.

High-grade B-cell lymphoma CD20, CD79a, CD3, CD10, cyclin D1, CD5, CD30, proliferation marker (Ki67 or equivalent) and bcl-2 protein.

T-cell lymphomas CD3, CD4, CD8, CD30, proliferation marker (Ki67 or equivalent) as well as CD20 and antibodies against follicular dendritic cells (FDCs: CD21, CD23, CD35 or CNA.42). Antibodies reacting against CD2, CD5 and CD7 antigens can be useful for demonstrating loss of one or more T-cell-associated antigens.

Hodgkin lymphoma CD15, CD30, CD20, CD3, MUM1, EMA, LMP-1 and proliferation marker (Ki67 or equivalent).

Important additional markers for haematopathology ALK-1, EMA, CD21 and other FDC markers, CDw76 (DBA.44) and annexin A1, plasma cell marker (VS38 or CD138-syndecan), CD68 and CD163, and CD1a and langerin. A range of markers for non-haematopoietic and myeloid proliferations also needs to be available.

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Table 1.1 Differential diagnosis between lymphoma and non-haematopoietic tumours (i.e. undifferentiated carcinoma and malignant melanoma) Antibodies/Clones

Major reactivities

Unexpected reactivities: remarks

CD45

Leukocyte common antigen (LCA) expressed by 90% of B- or T-cell lymphomas Some large-cell lymphomas, in particular anaplastic large-cell lymphoma and lymphoblastic lymphoma, are weakly positive or even negative for LCA Erythroblasts and megakaryocytes are negative Reed–Sternberg cells are usually negative

Exceedingly rare

LSP1 Clone: LSP1

Most lymphomas and myeloproliferative disorders

No cross-reactivity has been reported

EMA Clone E29

Epithelial membrane antigen expressed by most carcinomas Various benign or malignant tumours of diverse origin >80% of anaplastic large cell lymphomas

Expressed by : L&H cells (>80%) in lymphocyte predominance Hodgkin disease; 10% of large B- or T-cell lymphomas; erythroblasts

Cytokeratin clones: 1. KL1 2. MNF116 3. CAM 5.2 4. AE1/3

Most carcinomas are positive Numerous non-epithelial neoplasms may be positive: sarcoma, melanomas, etc.

Occasional lymphoma and plasma cell tumours may show a cytoplasmic dot-like staining

HMB45 Clone HMB45

Melanocytic proliferation; malignant melanoma

Reacts with angiomyolipoma of the kidney and clear cell sarcoma

PNL2 Clone PNL2

Melanocytic proliferation; malignant melanoma

Reacts with angiomyolipoma of the kidney and clear cell sarcoma; granulocytes

S100 Polyclonal

Reacts with S100 A and B Most malignant melanomas are positive

Reacts with a wide variety of normal cells and tumours

Two clones 2B11 and PD7/26

Pitfalls in immunohistochemistry Although immunohistochemistry allows the diagnosis of most lymphoid tumours, there are some that remain difficult to identify. Several factors are responsible for diagnostic difficulties and pitfalls in immunohistochemistry, and quality control has often been raised as a critical issue. False-negative staining is more common than false-positive staining (with the notable exception of false-positive staining due to passive absorption of extracellular Ig) and fixation is the most common culprit. The following discussion is restricted to the labelling of paraffin-embedded biopsy specimens

False-negative staining False-negative staining may be due to denaturation of either antigen or antibody. As far as the denaturation of the antigen is concerned, one must bear in mind that the gold standard in immunohistochemistry is the labelling on frozen sections which preserves all antigens. However, antigens surviving fixative or that can be retrieved using a number of procedures such as microwave oven heating [1] are now well known. Nevertheless, in some tissue specimens, even after

Occasional seminomas or primitive sarcomas positive for CD45 have been reported Exceptional carcinomas may show strong CD45 cytoplasmic staining though this is generally a misinterpretation of macrophages within the tumour

using the latter procedure, some antigens cannot be retrieved, mainly because of the length of the fixation or the nature of the fixative or for other unknown reasons. We have noted that, in a given tissue specimen, some antigens are better preserved than others. Fortunately, in most cases, there is an internal control (i.e. normal B lymphocytes for B-cell antigens, plasma cells for Ig or epithelial membrane antigen [EMA] staining) which, if absent, may indicate that we are dealing with a false-negative staining. Of course, the lack of internal controls may also be related to technical problems involving one or several steps of the staining protocol. Sections stained in the same batch are usually good external controls to rule out such a pitfall. A number of laboratories use positive and negative tissue specimens such as tonsil for B, T and cytokeratin stainings that are subjected to the same immunohistochemical procedure as the samples stained for diagnostic purpose. Sometimes these are mounted on the same slides as the diagnostic sections. This is convenient provided that one is aware of this and does not score the control staining instead of the diagnostic specimen. It is worth noting that a positive staining

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Table 1.2 Monoclonal antibodies of diagnostic value T-cell markers

4

Antibodies/Clones

Major reactivities

Unexpected reactivities: remarks

CD1a Clone: O10

Reacts with cortical thymocytes, Langerhans cells and interdigitating dendritic cells Of diagnostic value in Langerhans cell histiocytosis Some precursor T-cell lymphomas are also positive

No reported cross-reactivity

CD2 Clone: AB75

Reacts with most T cells Most T-cell lymphomas are positive

<5% of examples of classic Hodgkin lymphoma (CHL) show reactivity in Reed–Sternberg (RS) cells

CD3 (polyclonal) CD3: monoclonal

Intracytoplasmic domain of CD3 ε-chain Reacts with most T-cell lymphomas (>75%) Reacts with cytoplasmic CD3 in about 50% of natural killer (NK) cell lymphomas Frequently negative or weakly positive in anaplastic large cell lymphoma

Exceptional cases of malignant lymphoma express CD3 and CD20 The RS cells in <5% of examples of CHL show a dot-like staining in the Golgi area Some (<10%) cases of acute myeloid leukaemia (AML) are CD3+ Megakaryocytes may show a weak non-specific cytoplasmic staining

CD4 Clone: 1F6 MT310

Reacts with transmembrane glycoprotein found on helper/inducer T cells Good marker for CD4+ T-cell lymphomas

Macrophages are positive for CD4 True histiocytic tumours and Langerhans cell histiocytosis are CD4 + <5% of examples of CHL show reactivity in RS cells

CD5 Clone: 5C7

Reacts with thymocytes and T cells in lymph nodes A small subpopulation of B cells in lymph nodes is CD5+ Most T-cell lymphomas and leukaemias are positive

Antibody of diagnostic value (together with other antibodies for the diagnosis of chronic lymphocytic leukaemia (CLL) (CD5+ in 95% of cases] and mantle cell lymphoma (CD5+ in 90% of cases] Some thymic carcinomas are CD5+

CD7 Clone: CBC37

Expressed by thymocytes and T cells in lymph nodes and spleen Most nodal T-cell lymphomas positive This antigen is frequently absent in cutaneous T cell and some other peripheral T-cell lymphomas

Some myeloid leukaemias are positive

CD8 Clone: C8/144B

Expressed by cytotoxic/suppressor T cells

Useful antibody for labelling lymphomas and leukaemias derived from cytotoxic/suppressor T cells

CD43 Clones: MT1, DF1, Leu-22

Detects sialophorin expressed on the cell membrane of myeloid cells, T cells and some histiocytes and plasma cells Most T-cell lymphomas are positive Most anaplastic large cell lymphomas (CD3−) are positive for CD43 Langerhans cell histiocytosis and true histiocytic neoplasms are positive RS cells in Hodgkin lymphoma are negative

Useful antibody for the diagnosis of mantle cell lymphoma (>50% positive) and marginal zone lymphoma (>25% positive) as well as CLL/small lymphocytic lymphoma (SLL) (80% positive) Precursor lymphoblastic B-cell lymphomas are often positive (60% of cases) Epstein–Barr virus (EBV)-positive large cell lymphomas are often positive

CD45RO Clone: UCHL1

Subpopulation of T cells (memory) and macrophages Most peripheral T-cell lymphomas In autoimmune lymphoproliferative syndrome (ALPS) the CD45RO+ memory T cells are decreased and the CD45RA+ naïve T cells are increased

Some B-cell lymphoma and plasma cells neoplasms are positive Reacts with myelomonocytic cells and granulocytes

CHAPTER 1

General Introduction

Table 1.2 (continued) T-cell markers Antibodies/Clones

Major reactivities

Unexpected reactivities: remarks

βF1 TCR β chain Clone: 8A3

Reacts with a non-polymorphic determinant of the β chain of the T-cell antigen receptor (TCR) Most T-cell lymphomas expressing αβ receptors are positive for βF1. However, on paraffin sections the staining is strongly dependent on the fixative and length of fixation

RS cells in Hodgkin lymphoma may show a focal paranuclear staining in 10% of cases

TCR γ chain Clone: γ3.20

Recognises γδ T cells in normal and neoplastic conditions

Useful in identifying rare cases of γδ T-cell lymphoma No reported cross-reactions

B-cell markers Antibodies/Clones

Major reactivities

Unexpected reactivities: remarks

CD20 Clone L26

Phosphoprotein expressed by more than 90% of B-cell lymphomas: Precursor B-lymphoblastic and diffuse large B cell with plasmacytic differentiation may be negative L&H (lymphocytic and histiocytic) cells of LP Hodgkin lymphoma RS cells in classic Hodgkin lymphoma are positive in 30% of cases but staining varies from cell to cell

Occasional T-cell lymphomas are positive Non-specific granular cytoplasmic staining can be found in some macrophages Non-specific nucleolar staining may be observed in a variety of haematopoietic and non-haematopoietic tumours (e.g. in RS cells or in carcinomas) Epithelial cells in thymoma may be CD20+ Rare cases (<5%) of AML are CD20+

CD23 Clone: MHM6, 1B12

Reacts with follicular dendritic cells and a variable proportion of mantle zone lymphocytes Expressed by 90% of B-CLL cases Other neoplasms are usually negative

About 70% of mediastinal large B-cell lymphomas are positive Subset of B-cell lymphomas positive (25% of follicular, 10% of marginal zone, <10% of non-mediastinal large B-cell, 5% of mantle cell)

CD45RA Clone: DBB42

Reacts with B cells in lymph nodes and spleen A subset of T cells (large granular lymphocytes or LGLs) and naïve T cells as well as histiocytes/ macrophages express this antigen Most B-cell lymphomas are positive Naïve T-cells increased in autoimmune lymphoproliferative syndrome

Large granular lymphocytic leukaemias and approximately 20% of other T-cell lymphomas are positive

CD76-like Clone: DBA-44

Reacts with mantle zone lymphocytes and scattered immunoblasts in lymph node pulp Of diagnostic value in hairy cell leukaemia, in particular for detecting minimal or residual bone marrow involvement in patients after treatment diffuse large B-cell lymphomas are frequently positive.

Endothelial cells are weakly positive Erythroblasts may be positive

CD79a Clone JCB 117

Detects mb1 protein associated with surface immunoglobulin (SIg) In contrast to CD20 the staining is mainly cytoplasmic Reacts with virtually all B-cell lymphoma including those with plasma cell differentiation

50% of lymphoblastic T-cell lymphomas are positive Rare cases of other T-cell lymphomas including extranodal NK T-cell lymphoma are positive for CD3 and CD79a Some smooth muscle cells show a cytoplasmic staining

Anti-Ig heavy and light chains

On paraffin sections only cytoplasmic Ig routinely detectable

False-positive staining may be observed on a variety of cells (i.e. RS cells) and tumours because of passive absorption of extracellular Ig (continued)

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Table 1.2 (continued) B-cell markers Antibodies/Clones

Major reactivities

Unexpected reactivities: remarks

PAX5 Clone: NCL-L-PAX5

Pax5 encodes for a B-cell-specific transcription factor that is expressed in pro-B cells and subsequently in all stages of B-cell development until the plasma cell stage in which it is downregulated

Also positive on most RS cells which can be useful in the distinction of CHL from anaplastic large-cell lymphoma (ALCL)

IgD Clone: IgD26

Reacts on paraffin sections with SIgD of small B lymphocytes of mantle zone CLL and mantle cell lymphomas are usually positive

None reported

CD138/Syndecan 1

Reacts with reactive and neoplastic plasma cells Large B-cell lymphomas with plasma cell differentiation are positive

Reacts with a variety of non-haematopoietic neoplasms, in particular squamous cell carcinoma

OCT2 and BOB1 Clones: PT1, sc955

These are two B-cell transcription factors that are generally used together to help distinguish CHL (usually negative) from B-cell lymphomas and nodular lymphocyte-predominant Hodgkin lymphoma (positive)

VS38 Clone: VS38

Recognises the p63 antigen on ribosomes Reacts strongly with most reactive and neoplastic plasma cells Large B-cell lymphomas with plasma cell differentiation are positive

Reacts with a variety of non-haematopoietic neoplasms, especially endocrine tumours

BCL6

In normal lymphoid tissue BCL-6 is preferentially expressed by germinal centre cells but not by immature B-cell precursors or plasma cells Most diffuse large B-cell lymphomas are BCL-6+ L&H cells in lymphocyte predominance Hodgkin lymphoma are usually positive whereas in only 50% of classic Hodgkin lymphoma RS cells are BCL-6+

BCL-6 is found in CD4+ cells within germinal centres and in scattered T cells in the perifollicular areas Cortical thymocytes and T-cell lymphoblastic lymphomas are often BCL-6+

Annexin A1 Clone: 29

37-kDa calcium and phospholipids-binding protein is a strong inhibitor of glucocorticoid-induced eicosanoid synthesis and phospholipase A2 Positive on virtually all cases of hairy cell leukaemia but not on any other B-cell lymphomas

Neutrophils, monocytes, macrophages, subset of CD4+ T cells Many carcinomas are positive

Histiocytic markers

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Antibodies

Major reactivities

Unexpected reactivities: remarks

CD68 Clone: KP1

Stains macrophages in a wide variety of human tissues and plasmacytoid dendritic cells in lymph nodes Reacts with all true histiocytic tumours Reacts with myeloid precursors and granulocytes Most AMLs show strong cytoplasmic staining

Some B-cell lymphoma leukaemias such as CLL and hairy cell leukaemia may show a weak granular cytoplasmic staining Some ALCLs are positive Reacts with melanomas

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General Introduction

Table 1.2 (continued) Histiocytic markers Antibodies

Major reactivities

Unexpected reactivities: remarks

CD68 Clone: PGM1

Stains macrophages in a wide variety of human tissues and plasmacytoid dendritic cells in lymph nodes Reacts with all true histiocytic tumours but only M4 and M5 AMLs are positive

in contrast to KP1 this antibody does not cross-react with myeloid cells acute myeloid leukaemias M1, M2, M3, M6 and M7 types are negative

CD163 Clone: NCL-CD163

CD163 antigen is restricted in its expression to the monocytic/macrophage lineage. It is present on all circulating monocytes and most tissue macrophages

Exceptions are macrophages found in the mantle zone and germinal centres of lymphoid follicles. It does not stain interdigitating reticulum cells or Langerhans cells

Lysozyme

Stains macrophages in a wide variety of human tissues Reacts with all true histiocytic tumours Acute and chronic myeloid leukaemias

Frequent background staining

S100 protein

Stains Langerhans cells and interdigitating reticulum cells Virtually all cases of Langerhans cell histiocytosis are positive

Many non-haematopoietic neoplasms express this antigen, especially melanoma

CD207 Langerin Clone: 12D6

Langerin (CD207) is a type II membraneassociated C-type lectin known to be expressed exclusively by Langerhans cells. Langerin recognises mannose residues via its single carbohydrate recognition domain (CRD)

Occasional focal staining in non-Langerhans cell histiocytic sarcomas

Activation and proliferation markers Antibodies

Major reactivities

Unexpected reactivities: remarks

CD30 Clone: Ber-H2 or JCM182

Glycoprotein of the tumour necrosis factor/nerve growth factor (TNF/NGF) receptor family Activated B or T cells RS cells in classic Hodgkin lymphoma show membranous and paranuclear cytoplasmic staining. Positivity restricted to the paranuclear area is seen in some cases which may be related to fixation Anaplastic large-cell lymphomas Some large T- or B-cell lymphomas

Embryonal carcinoma With some fixatives plasma cells (BerH2) or granulocytes ( JCM182) may show cytoplasmic staining Rare undifferentiated squamous carcinomas are positive Mastocytosis is positive About 70% of mediastinal large B-cell lymphomas are positive

Ki-67/MIB1

Reacts with a nuclear antigen expressed in G1, S, G2 and M phases of the cell cycles Useful antibody to assess the growth fraction rate in lymphoproliferative disorder; In some overfixed specimens the staining may be restricted to nucleoli or mitotic figures

None reported consistently

(continued)

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Table 1.2 (continued) Myeloid, erythroblast and megakaryocyte markers Antibodies

Major reactivities

Unexpected reactivities: remarks

CD15 Various clones

Detects the X hapten, a late differentiation marker of myeloid cells, also expressed by some monocytes and epithelioid cells Membranous and paranuclear cytoplasmic staining. Positivity restricted to the paranuclear area is seen in some cases which may be related to fixation Useful in the diagnosis of Hodgkin lymphoma: 80% of cases are positive Some T-cell lymphomas and occasional B-cell lymphomas are positive About 5% of anaplastic large-cell lymphoma are positive but the staining is weaker than that of RS cells

This antigen is expressed by many normal and malignant epithelial cells. Cytomegalovirus (CMV)-infected cells label for CD15

CD31 Clone: JC70

Endothelial cells, platelets and megakaryocytes Some reactive and neoplastic plasma cells and histiocytes are labelled

Vascular tumours

Myeloperoxidase

Granulocytes and their precursors Useful markers for the diagnosis of extramedullary myeloblastic proliferations AMLs are positive

Systemic and skin mast cell proliferations are positive Some macrophages, e.g. in Kikuchi disease, are also positive

Anti-von Willebrand factor Clone: F8/86

Reacts with von Willebrand factor in megakaryocytes (cytoplasmic staining) Megakaryoblastic leukaemia (M7)

Endothelial cells

CD61 GpIIIa

Megakaryocytes and platelets Megakaryoblastic leukaemia

Reacts with endothelial cells and osteoclasts

Elastase Clone: NP57

Reacts with neutral protease of granulocytes and their precursors Most AMLs are labelled

A few monocytes are weakly labelled

Follicular dendritic cells (FDCs)

8

Antibodies/Clones

Major reactivities

Unexpected reactivities: remarks

CD21 Clones: IF8, 2G9, DR53

Reacts with C3d complement receptor Stains the FDC network in normal and neoplastic lymphoid tissue

Also positive on a small number of B-cell lymphomas of all types and some cases of T-cell lymphoblastic Positive in many littoral cell angiomas

CD35 Clones: Ber-MacDRC, C3br, TO5

Reacts on paraffin sections with the C3b receptor of complement (CR1) Stains the FDC network but the reactivity is strongly dependent on the type and length of fixation

Reacts with epithelial cells of renal glomeruli Positive on epithelial cells in inflammatory conditions and many carcinomas

CD23 Clones: MHM6, 1B12

Reacts with follicular dendritic cells and a variable proportion of mantle zone lymphocytes

Expressed by B-CLL and some follicular, marginal zone and infrequent mantle cell lymphomas About 70% of mediastinal large B-cell lymphomas are positive Other neoplasms are usually negative

CHAPTER 1

General Introduction

Table 1.2 (continued) Follicular dendritic cells (FDCs) Antibodies/Clones

Major reactivities

Unexpected reactivities: remarks

CNA-42 (NC) Clone: CNA.42

Reacts with FDCs and scattered mononuclear cells in the lymph node pulp Some cortical thymocytes are positive useful for demonstrating FDC meshworks in follicular lymphoma and some T-cell lymphomas FDC sarcomas are positive as well as some inflammatory pseudotumours of FDC origin

Mast cells, endothelial cells and a subpopulation of plasma cells are labelled Anaplastic large-cell lymphomas are positive (60%) 40% of T-cell lymphomas are positive weak-to-moderate cytoplasmic staining is found in 20% of cases of Hodgkin lymphoma rare cases of large B-cell lymphoma (5%) are positive

Miscellaneous Antibodies

Major reactivities

Unexpected reactivities: remarks

BCL-2 Clones: 124, 3.1

Protein able to suppress cell death by apoptosis B and T small lymphocytes are positive but germinal centre cells in reactive lymph nodes are negative Very helpful in the diagnosis of follicular lymphoma (85% +) versus follicular hyperplasia; Most B- or T-cell lymphoma are positive RS cells in Hodgkin lymphoma are frequently positive (60% of cases)

Most AMLs and chronic myeloid leukaemia (CML) in blast crisis are positive Blasts in refractory anaemia with excess of blasts are positive Many normal and malignant epithelial cells are positive

Cyclin D1

Reacts with cyclin D1 antigen Nuclear staining very helpful in diagnosing mantle cell lymphoma

Hairy cell leukaemias and many cases of myeloma are positive Cytoplasmic staining is not considered to be specific

ALK Clone: ALK1

Highly specific for the NPM/ALK protein associated with the t(2;5) and full-length ALK protein Reacts with 85% of anaplastic large cells lymphoma of T or null phenotype Cytoplasmic, nuclear and nucleolar staining is highly indicative of the t(2;5) (90% of cases) 20% cases show a staining restricted to the cytoplasm. These cases are associated with ALK variant translocations (TPM3-ALK, TFG-ALK, ATIC-ALK, etc.)

Rare cases of large B-cell lymphoma (CD30−, EMA+, IgA+) show ALK-positive staining restricted to the cytoplasm of malignant cells Some inflammatory myofibroblastic tumours associated with TPM3-ALK, TPM4-ALK, CLTC-ALK or RanBP2-ALK protein show ALK-positive staining restricted to the cytoplasm of neoplastic cells

TIA1

Granule-associated cytotoxic protein of cytotoxic T cells, NK cells and granulocytes Granular cytoplasmic staining is seen in some peripheral T-cell lymphomas, in particular in anaplastic large-cell lymphoma

Occasional cases of classic Hodgkin lymphoma show positive RS cells As a result of granulocytes labelling in bone marrows, another marker for cytotoxic granules such as granzyme B may be preferred in this setting

MUM1 Clone: MUM1p

Labels MUM1 protein in a subset of light zone germinal centre (GC) B cells (probably centrocytes and their progeny), plasma cells, activated T cells and a wide spectrum of haematolymphoid neoplasms derived from these cells; MUM1 protein is a useful tool for identifying RS cells in classic Hodgkin lymphoma as virtually all are positive

Of non-haematolymphoid neoplasms, only a proportion of melanomas are labelled

(continued)

9

CHAPTER 1

General Introduction

Table 1.2 (continued) Miscellaneous Antibodies

Major reactivities

Unexpected reactivities: remarks

Perforin

Granule-associated cytotoxic protein of cytotoxic T cells Granular cytoplasmic staining is seen in some peripheral T-cell lymphomas in particular in anaplastic large-cell lymphoma

Useful antibody in the differential diagnosis between neoplastic cell-rich Hodgkin lymphoma (perforin negative) and anaplastic large cell lymphoma (frequently positive)

Granzyme B

Granule-associated cytotoxic protein of cytotoxic T cells Granular cytoplasmic staining is seen in some peripheral T-cell lymphomas

TdT Rabbit anti-TdT

Reacts with terminal deoxynucleotidyl transferase Most cortical thymocytes are positive (nuclear staining) Small population (<1%) of bone marrow lymphoid cells Most precursor B- and T-lymphoblastic leukaemia/ lymphoma is TdT+

Exceptionally found in a few cells in reactive lymph nodes, tonsils and spleens Cytoplasmic staining is considered to be non-specific Some cases of AML are positive

CD10

Positive on most B lymphoblastic lymphoma/ leukaemias and some T lymphoblastics Most germinal centre cells are positive as are about 80% of follicular lymphomas Some large B-cell lymphomas are positive

Stromal cells in a variety of tissues are positive, making a useful internal control Angioimmunoblastic T-cell lymphomas are often labelled for CD10 but newer markers such as BCL6, CXCL13 and PD1 more often label these follicular helper T cells

CD34 Clone: QBEN10

Glycoprotein expressed by lymphohaematopoietic stem and progenitor cells Reacts with precursor B- or T-lymphoblastic lymphoma/leukaemia AMLs are also labelled

Endothelial cells Vascular tumours Some sarcomas

CD56

reacts with neural cellular adhesion molecule (NCAM) NK neoplasms in particular T/NK cell nasal lymphoma

CD56 is expressed by 20% of AML and in myeloblasts of high-grade myelodysplastic syndromes

CD57 Clones: IOT10 anti-Leu7

Carbohydrate antigen expressed on mononuclear cells with NK activity Some T-lymphoblastic lymphomas and NK tumours are positive Occasional large B-cell lymphomas are positive Lymphocytes forming rosettes around lymphocytepredominant (LP) cells in LP Hodgkin lymphoma are often CD57+

Reacts with a variety on non-haematopoietic neoplasms such as prostatic carcinoma and neuroendocrine tumours

Anti-HLA-DR Clone: DK22

Expressed by most B-cell lymphomas Occasional T-cell lymphomas developed from activated T cells are positive Langerhans cell histiocytosis is positive Histiocytic tumours are usually positive

Various non-lymphoid tumours are positive for HLA-DR

c-kit (CD117)

Mast cells and mastocytosis are strongly positive Many cases of AML and blast cells in myelodysplasia are positive

Various lymphoid and non-lymphoid tumours (e.g. gastrointestinal stromal tumours or GISTs) are positive for c-kit

10

CHAPTER 1

General Introduction

Table 1.2 (continued) Miscellaneous Antibodies

Major reactivities

Unexpected reactivities: remarks

Vimentin Clone V9

Occasional B- or T-cell lymphomas are positive RS cells in Hodgkin lymphoma are usually positive

Expressed by a wide variety of benign and malignant cells

Fascin Clone: K-2

Reacts with actin-bundling protein expressed by dendritic cells Stains dendritic cells (interdigitating reticulum cells) in lymph nodes RS cells in classic Hodgkin’s disease are usually positive (L&H cells are negative) Langerhans cell histiocytosis is positive

FDCs are weakly to moderately positive Endothelial cells are strongly positive Occasional B- or T-cell neoplasms are positive

Infectious agents Antibodies

Major reactivities

Unexpected reactivities: remarks

p24 Clone: Kal-1

HIV type 1 capsid protein Reacts with the p24 protein in FDCs infected by HIV

Background staining may be responsible for false positive staining

CMV Clones: 2A2, E13

Reacts with early antigen (EA) detected during the CMV infection

LMP1 Clone: CS1-4

Reacts with EBV latent membrane protein in latently infected cells Immunoblasts in infectious mononucleosis are LMP1+ Many cases of classic Hodgkin lymphoma are positive Most large B-cell lymphomas in HIV-positive patients and post-transplantation B-cell lymphomas are positive Scattered non-neoplastic B-cell immunoblasts are found in some peripheral T-cell lymphomas T/NK cell lymphoma latently infected by EBV (i.e. nasal-type lymphomas) are usually negative (but positive for EBV RNA or EBER)

Reactive plasma cells may show a non-specific cytoplasmic staining In some bone marrow biopsies megakaryocytes may show a strong cytoplasmic staining Extensive non-specific labelling may be observed in B-5-fixed sections

EBNA2 Clone: PE2

EBV nuclear antigen expressed in latently infected cells EBV-positive, large B-cell lymphomas express this antigen EBV-positive RS cells are negative for EBNA2

On paraffin section the staining is usually weak

HHV8 Clone: LN53

This antibody reacts with the latent nuclear antigen (LNA-1) of human herpesvirus 8 (HHV8) Kaposi sarcoma and lymphoid cells in multicentric Castleman disease are positive

Positive in primary effusion lymphomas as well as the large B-cell lymphomas that arise in HHV8+ multicentric Castleman disease

11

CHAPTER 1

General Introduction

of the control samples and a negative staining of the tested sample do not exclude the possibility of false staining because the various steps in the preparation of the tissue sample (including length of fixation and type of fixative) may be different. In addition, control tissue on the same slide may be falsely negative on some staining platforms if control tissue is not placed close enough to the target tissue because reagents may not cover the entire slide. Once again, the presence of an internal positive control is the most reliable criterion to decide whether neoplastic cells in a given biopsy specimen are negative or not. Finally, false-negative staining may be due to antibodies that are not suitable for immunohistochemistry even though they are perfectly good reagents for other techniques such as western blotting.

False-positive staining If one excludes background staining, non-specific labelling may be related to contaminating antibodies in the primary serum (i.e. anti-IgG reactivity in an anti-IgM antiserum). Such non-specific staining may be decreased by increasing the dilution of the primary antibody. The most common false-positive staining in lymphoid pathology is due to passive absorption of extracellular proteins (i.e. Ig and other serum proteins) by neoplastic cells [2]. In some malignant lymphoid proliferations this phenomenon may be responsible for an erroneous diagnosis of a reactive disorder on the basis of a false polytypic staining (i.e. lymphoma cells positive for Igκ and Igλ) because neoplastic cells have passively absorbed IgGκ and IgGλ, which are in large amounts in the serum and thus in the extracellular milieu. For unknown reasons, large cells in diffuse large B-cell lymphoma and Reed–Sternberg cells or even histiocytes have a great tendency to absorb passively extracellular proteins. Some signs may allow the recognition of false-positive staining due to passive absorption: • The staining is diffuse rather than granular and the nucleus is often stained. • Positive cells are scattered among a majority of negative cells. • The artefactual staining is proportional to the concentration of proteins in the serum (IgG > IgM). • Double staining for κ and λ reveals mixed staining • J-chain staining may be helpful for differentiating positive Ig-secreting cells (J chain positive) from cells having passively absorbed extracellular Ig (J chain negative). Unfortunately there is not at present a good commercially available anti-J chain antibody for use on routine specimens.

Unexpected reactivity of monoclonal antibodies Some antibodies, which are very useful in routine immunohistochemistry, may show a very confusing, unexpected reactivity with some normal or neoplastic cells. One of the

12

best examples of this phenomenon is represented by the reactivity of anti-EMA antibodies.

Anti-EMA antibodies Anti-EMA usually refers to the commercially available antiEMA/E29 antibody, although there are other antibodies reacting with epithelial membrane antigen. Positive staining of a subset of plasma cells was recognised early in the history of EMA and now constitutes an acceptable internal control in haematolymphoid tissues [3]. The staining is mainly membrane associated. The most consistent reactivity of EMA within B-cell neoplasms is found in multiple myeloma and plasmacytoma [4]. In hyperplastic bone marrow showing increased numbers of immature cells, some erythroblasts may react with anti-EMA antibody. However, the membrane staining is usually weak, and sometimes the staining is restricted to the Golgi area (dot-like staining). Caution is therefore required when using anti-EMA antibodies for detecting marrow involvement in epithelial malignancies or in patients with anaplastic large-cell lymphoma (see below). Blastic cells in erythroleukaemia and megakaryoblastic leukaemia may also express EMA. The most frequent non-epithelial expression of EMA is recorded in the LP cells of nodular lymphocyte-predominant Hodgkin lymphoma and the cumulative experience of the reactivity of LP cells with anti-EMA approaches 80% of cases [5–7]. In cases with apparently negative atypical cells, comparison with the staining intensity of plasma cells as the internal control is critical. Many cases of transformation of nodular lymphocyte-predominance Hodgkin lymphoma to large B-cell lymphoma have been shown to conserve EMA expression [6]. The situation is quite different in classic Hodgkin lymphoma of nodular sclerosis and mixed cellularity subtypes. The reactivity of anti-EMA with Hodgkin and Reed–Sternberg cells and variants is exceedingly rare at less than 5% [4]. The percentage of cases with EMA+ Reed–Sternberg cells is even lower if only the larger reported series are taken into account which suggests that the finding of EMA+ Reed–Sternberg cells and variants should lead to a reassessment of a diagnosis of classic Hodgkin lymphoma. The series of Filippa et al. [8] of 128 cases of nodular sclerosis and mixed cellularity subtypes without EMA expression is notable, and the authors attached clinical significance to the non-expression of EMA in classic Hodgkin lymphoma. Nevertheless, there are probably rare cases where the diagnosis of classic Hodgkin lymphoma is sustainable by morphology and other antibodies (CD15+, CD30+, MUM1+, null cell phenotype) despite the expression of EMA. Within the lymph node-based, low- and high-grade, B-cell lymphomas, reactivity of EMA is of the order of 5% in major series. EMA is mainly expressed by T-cell-rich B-cell lymphomas and by diffuse large B-cell lymphomas. A distinct subtype of large B-cell lymphoma expressing EMA strongly

CHAPTER 1

together with the tyrosine kinase receptor ALK has been recognised [9]. The presence of EMA on T-cell lymphomas is of the order of 10–20% in larger series [3]. Most cases of enteropathyassociated T-cell lymphoma and anaplastic large-cell lymphoma express EMA [10]. EMA expression in CD30+ primary cutaneous lymphoproliferative disorders is still the subject of controversy. In our experience EMA is expressed by most CD30+ tumours and is not of diagnostic value for differentiating secondary from primary CD30+ cutaneous lymphomas.

Anti-CD30/Ber-H2 antibody The reactivity of this antibody was first reported in reactive B and T immunoblasts, Reed–Sternberg cells, and is now the defining marker of anaplastic large cell lymphoma [11]. A subpopulation of plasma cells is reactive for CD30/Ber-H2 antibody in formalin-fixed tissue, although this is not seen when heat-associated antigen retrieval methods are used [11]. However, the range of neoplastic cells expressing the CD30 antigen is wider than initially thought [12]. Mastocytosis is commonly positive for CD30 and the authors have observed that occasional cases of true histiocytic tumours and erythroleukaemia are also positive for this antigen. Some non-haematopoietic cells are positive for CD30/ Ber-H2. In addition to the well-known reactivity of embryonal carcinoma, various carcinomas and occasional melanomas may show a reactivity for CD30/Ber-H2(12). A new clone, JCM182, specifically produced to improve the recognition of CD30 on paraffin sections has recently become available. It too has a few unexpected reactions such as identifying granulocytes especially in bone marrow specimens.

Miscellaneous unexpected reactivities Some of these reactivities are commonly seen in routine practice and are not really a source of error:

General Introduction

the expression of CD79a, lymphoblastic lymphomas that are positive for CD3 and CD79a are of T-cell lineage [16]. Occasional cases of extranodal NK/T-cell and peripheral T-cell lymphoma may express CD79a antigen [17,18]. The reported positivity of acute promyelocytic leukaemia occurs only with the clone HM57 and not with the more commonly used reagent JCB 117 [19].

CD3 In various lesions, macrophages may show a spurious globular cytoplasmic staining. The authors have observed exceptional cases of B-cell lymphoma with clonal Ig gene rearrangement positive for CD3. Acute myeloid leukaemias express CD3 (as well as other T-cell-associated antigens) in less than 10% of cases.

CD5 This pan-T-cell antigen is expressed by a wide variety of B-cell lymphomas including small lymphocytic lymphoma/ leukaemia, mantle cell lymphoma and occasional cases of diffuse large B-cell lymphomas. CD5 is also found in thymic carcinomas and other non-lymphoid neoplasms [20].

CD10 CD10 antibodies recognize a 100-kDa cell surface glycoprotein that is present in a variety of cell types. Originally this antigen was referred to as ‘common acute lymphoblastic leukaemia antigen’ or CALLA, because it was found to be expressed on the cell surface of most cases of acute lymphoblastic leukaemia (ALL) and thought to be specific for this lymphoproliferative disorder. CD10 antigen can be demonstrated not only on precursor B-cell or T-cell lymphoblastic lymphomas/leukaemias but also on follicular lymphomas, most Burkitt lymphomas and diffuse large B-cell lymphomas (30% of cases). CD10 is also expressed in a wide variety of non-neoplastic human cells, including haematopoietic (germinal centre cells and mature granulocytes), epithelial (renal proximal tubules, bile canaliculi) and stromal cells (fibroblasts).

CD20/L26 The nucleolar staining of large number of cells of many different tissue types with CD20/L26 is commonly observed and does not indicate a B-cell origin of these cells. Only membrane-associated staining should be taken into consideration. Rare cases of CD20+ T-cell lymphoma have been reported [13]. CD20 antigen has been reported in occasional cases (<5% of cases) of acute myeloid leukaemia and in epithelial cells of thymoma [14]. Some follicular dendritic cells are also reactive for CD20.

CD79a/JCB117 Unexpectedly, approximately 40% of lymphoblastic T-cell lymphomas are positive for CD79a [15]. However, despite

CD23 The CD23 molecule is a low-affinity IgE receptor found on B cells. It is a membrane glycoprotein of 45 kDa and is reported to be found on a subpopulation of peripheral blood cells, B lymphocytes and Epstein–Barr virus (EBV)transformed B-lymphoblastoid cell lines. Expression of CD23 antigen has been reported on monocytes and dendritic cells and is generally positive on most cases of B-CLL (B-cell chronic lymphocytic leukaemia). Although originally considered to be negative it has become clear that approximately 20–30% of follicular lymphomas are positive and increasingly positive cases of other subtypes of B-cell lymphoma are being recognised [21].

13

CHAPTER 1

General Introduction Most malignant lymphomas expressed the leukocyte common antigen CD45 and are negative for epithelial markers. There are, however, exceptions that are responsible for diagnostic difficulties in immunohistochemistry. According to the largest series in the literature, 10% of diffuse large cell lymphomas, 20% of lymphoblastic T-cell lymphomas and most plasmocytomas/myelomas are negative for CD45 [25–27]. Note that more than a third of anaplastic large-cell lymphomas are negative for CD45, the highest rate of negativity among non-Hodgkin lymphomas. Generally speaking, the larger the cells the weaker the expression of the leukocyte common antigen and in some cases this antigen is detected only on frozen sections. It is worth noting that some of these tumours are usually positive for EMA which may lead to an erroneous diagnosis of undifferentiated carcinoma. Additional markers of B- or T-cell lineage along with CD30 should enable a correct identification of the lymphoid nature of these tumours.

Anti-TdT antibody This antibody is very useful for diagnosing lymphoblastic lymphomas from B- or T-cell origin. However, approximately 10% of myeloblastic leukaemias are also positive for TdT. Furthermore cortical thymocytes are strongly positive so a diagnosis of T-lymphoblastic leukaemia in the thymus needs to be made on more than TdT positivity. In addition, there are increased numbers of TdT+ precursors in regenerating bone marrows, so TdT needs to be used with great caution when monitoring the bone marrow of ALL patients for evidence of minimal relapse.

CD68 antibodies The two anti-CD68 antibodies, PGM1 and KP1, do not have the same reactivity despite being in the same cluster. Thus, CD68/KP1 reacts with immature myeloid cells whereas CD68/PGM1 has a restricted reactivity with monocytes/ macrophages. A significant number of lymphocytic and diffuse large B-cell lymphomas are positive for KP1 [22] as are most melanomas [23,24] whereas PGM1 is unreactive with these tumours.

Loss of B- or T-cell-associated antigens In B-cell lymphoma the loss of both CD20 and CD79a antigens has been reported in rare cases of ALK (anaplastic lymphoma kinase)-positive large B-cell lymphoma secreting IgA [9]. Cases of CD20-positive B-cell lymphomas that became CD20 negative at relapse have been reported after rituximab therapy [17] (Fig 1.1).

Loss of leukocyte common antigen Malignant cells may lose one or more antigens usually found on normal cells of their origin. The best example is provided by malignant lymphomas negative for the leukocyte common antigen CD45.

HE

HE

Proliferation (mib1)

CD20

CD20

CD79a

Fig 1.1 Example of a follicular lymphoma that was CD20+ on diagnosis, but at relapse after rituximab therapy is virtually negative apart from a few dots of cytoplasmic staining. The lymphoma remains B cell, being CD79a+, and has the typical cytology and proliferation rate and pattern of a follicular lymphoma.

14

CHAPTER 1

In T-cell lymphomas the loss of one or more pan-T-cell antigens (CD3, CD5, CD2 or CD7) is seen in most cases (75% of cases), CD7 being the most frequent, particularly in cutaneous T-cell lymphomas [28–30]. Pan-T-cell antigens are commonly missing in anaplastic large-cell lymphomas with CD3 staining being observed in only a third of cases.

Acquisition of antigens Some malignant cells may express one or several antigens that are normally restricted to another cell lineage. The best example is provided by some lymphomas being positive for cytokeratin or some carcinomas reacting with anti-leukocyte antibodies.

Malignant lymphoma positive for keratin A number of reports have emphasised the existence of myelomas or large-cell lymphomas positive for cytokeratin

General Introduction

[26,31–35]. It is worth noting that, in these cases, the staining for cytokeratin is usually focal and restricted to the paranuclear Golgi area. Of note is that most of these tumours are negative for leukocyte common antigen which may increase the diagnostic difficulty. The diagnosis of lymphoma in these cases relies heavily on the reactivity with anti-T or anti-B antibodies. The authors have also observed rare cases of acute myeloblastic leukaemia positive for cytokeratin.

Other unexpected reactivities Some other unexpected reactivities have been reported such as B-cell lymphomas reactive for HMB45, the melanoma marker [36], and positivity for S100 protein, actin [37] and vimentin [38]. Unexpectedly, some cases of mediastinal B-cell lymphomas are positive for β human chorionic gonadotrophin (βhCG) [39]. In fact, these aberrant reactivities are rarely encountered in routine practice.

Capsule

Primary follicle

Paracortex Secondary follicle Sinuses

Fig 1.2 Principal structures in a normal lymph node. Normal lymph node structures are indicated. An abundance of primary follicles denotes a lymph node little affected as yet by antigenic stimulation.

Bcell (CD20)

Tcell (CD3)

15

CHAPTER 1

General Introduction

The normal lymph node

Primary follicles

Secondary follicles

Proliferation (Ki67)

Non-lymphoid tumors positive for the leukocyte common antigen

Squamous epithelium

Paracortex

Follicles Fig 1.4 Tonsil differs from lymph node principally by being covered by oral-type non-keratinising squamous epithelium. The sinus meshwork is also poorly developed and difficult to identify.

16

Fig 1.3 When follicles undergo secondary change on antigenic stimulation there is a greatly increased level of proliferation in the developing germinal centre which is predominantly in one area, the so-called ‘dark zone’ where the centroblasts are most numerous.

A more confusing aberrant phenotype is provided by some non-lymphoid tumours positive for the leukocyte common antigen (LCA). Warnke and Rouse [40] reported two cases, one an aggressive pituitary adenoma and the other a seminoma positive for LCA. Such reactivity has also been reported in non-malignant breast lesions [41]. We have observed two cases of breast carcinoma positive for LCA but in these cases the staining was mainly cytoplasmic and not membrane associated as in lymphoid tumours. However, a clear CD45 membrane staining has been reported in undifferentiated and neuroendocrine carcinoma [42]. It should be emphasised that these are exceptionally rare events in diagnostic practice. By far the most common reason for pathologists thinking that a carcinoma is CD45+ is by mistaking a heavy macrophage infiltration for malignant epithelial cells. This can be easily resolved by staining for CD68.

I’ve only got one H&E – help! No problem, except you can only do one immunostain so choose carefully. Just immerse the slide in toluene for 12– 72 h to remove the coverslip and then place in successive baths of absolute alcohol, distilled water and phosphatebuffered saline. This treatment removes the eosin staining

CHAPTER 1

General Introduction

White pulp

Red pulp

CD20

CD3

Fig 1.5 In the spleen the lymphoid tissue resides in the white pulp, which similar to lymph node contains well-circumscribed B- and T-cell areas.

of the cytoplasm, but does not affect the nuclear staining. Immunohistochemical staining is then performed as for unstained sections.

Conclusion This brief description of some pitfalls in immunohistochemistry stresses that the immunophenotypic diagnosis and the cellular origin of a tumour cannot rely on a single immunological marker. Aberrant stainings, such as positive staining

for cytokeratin in malignant lymphomas, or lymphomas negative for the LCA (CD45) do not diminish the diagnostic utility of immunohistochemistry, which allows the accurate classification of most if not all haematopoietic neoplasms. However, these unusual stainings emphasise the need to interpret immunohistochemical results with morphology and clinical data.

Molecular techniques ‘Molecular studies have revolutionized hematopathologic diagnosis’ writes an eminent author of a recent excellent

17

CHAPTER 1

General Introduction

lymph node textbook [43]. But have they? A positive rearrangement or translocation might be supportive but who feels confident enough to diagnose malignancy when only a band on a polymerase chain reaction (PCR) gel says so? Although these techniques remain expensive they have now become much more reliable in routine service. We continue to use PCR or fluorescent in situ hybridisation (FISH) methods as supportive in difficult cases, but do not rely on them for a diagnosis. So, for example, a B- or T-cell clonal rearrangement is helpful in a case with a strong suspicion of B- or T-cell malignancy as is an appropriate FISH translocation for suspected Burkitt lymphoma or mantle cell lymphoma. By themselves they are still insufficiently robust to deliver a diagnosis, although surely similar to telepathology their day will come (though for the moment we continue to wait patiently).

Normal lymphoid structures The key to virtually all pathological diagnoses is knowing and understanding the normal. It is difficult to define what a normal lymph node is because it is a structure that is changing and adapting daily. Figures 1.2 and 1.3 outline the basic structure of a lymph node, Fig 1.4 the tonsil and Fig 1.5 the spleen, and contrast the difference between an unstimulated node with its primary follicles and one that has been stimulated to produce secondary follicles with germinal centres.

9.

10.

11.

12. 13.

14. 15.

16.

17. 18.

19.

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and genetic characteristics and differences with Hodgkin’s disease. Blood 1996;87:2905–17. Delsol G, Lamant L, Mariame B, et al. A new subtype of large B-cell lymphoma expressing the ALK kinase and lacking the 2;5 translocation. Blood 1997;89:1483–90. Delsol G, Al Saati T, Gatter K, et al. Coexpression of epithelial membrane antigen (EMA), Ki-1, and interleukin-2 receptor by anaplastic large cell lymphomas: diagnostic value in so-called malignant histiocytosis. Am J Pathol 1988;130:59–70. Schwarting R, Gerdes J, Durkop H, Falini B, Pileri S, Stein H. BER-H2: a new anti-Ki-1 (CD30) monoclonal antibody directed at a formol-resistant epitope. Blood 1989;74:1678–89. Pallesen G. The diagnostic significance of the CD30 (Ki-1) antigen. Histopathology 1990;16:409–13. Algino KM, Thomason RW, King DE, Montiel MM, Craig FE. CD20 (pan-B cell antigen) expression on bone marrow-derived T cells. Am J Clin Pathol 1996;106:78–81. Chang KL, Arber DA, Weiss LM. CD20: A review. Appl Immunohistochem 1996;4:1–15. Pilozzi E, Pulford K, Jones M, et al. Co-expression of CD79a (JCB117) and CD3 by lymphoblastic lymphoma. J Pathol 1998; 186:140–3. Pilozzi E, Muller-Hermelink HK, Falini B, et al. Gene rearrangements in T-cell lymphoblastic lymphoma. J Pathol 1999; 188:267–70. Chu PG, Arber DA. CD79: a review. Appl Immunohistochem Mol Morphol 2001;9:97–106. Yao X, Teruya-Feldstein J, Raffeld M, Lynn Sorbara L, Jaffe ES. Peripheral T-cell lymphoma with aberrant expression of CD79a and CD20: A diagnostic pitfall. Mod Pathol 2001;14:105–10. Arber DA, Jenkins KA, Slovak ML. CD79 alpha expression in acute myeloid leukemia. High frequency of expression in acute promyelocytic leukemia. Am J Pathol 1996;149:1105–10. Kornstein MJ, Rosai J. CD5 labeling of thymic carcinomas and other nonlymphoid neoplasms. Am J Clin Pathol 1998;109: 722–6. Thorns C, Kalies K, Fischer, et al. Significant high expression of CD23 in follicular lymphoma of the inguinal region. Histopathology 2007;50:716–19. Carbone A, Gloghini A, Volpe R, Pinto A. KP1 (CD68)-positive large cell lymphomas: a histopathologic and immunophenotypic characterization of 12 cases. Hum Pathol 1993;24:886–96. Facchetti F, Bertalot G, Grigolato PG. KP1 (CD 68) staining of malignant melanomas. Histopathology 1991;19:141–5. McHugh M, Miettinen M. KP1 (CD68). Its limited specificity for histiocytic tumors. Appl Immunohistochem 1994;2:186–90. Van Eyken P, De Wolf-Peeters C, Van den Oord J, Tricot G, Desmet V. Expression of leukocyte common antigen in lymphoblastic lymphoma and small noncleaved undifferentiated non-Burkitt’s lymphoma: an immunohistochemical study. J Pathol 1987;151:257–61. Wotherspoon AC, Norton AJ, Isaacson PG. Immunoreactive cytokeratins in plasmacytomas. Histopathology 1989;14:141–50. Weiss LM, Arber DA, Chang KL. CD45. A review. Appl Immunohistochem 1993;1:166–81. Picker L, Weiss L, Medeiros L, Wood G, Warnke R. Immunophenotypic criteria for the diagnosis of non-Hodgkin’s lymphoma. Am J Pathol 1987;128:181–201.

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29. Warnke RA, Weiss LM. Practical approach to the immunodiagnosis of lymphomas emphasizing differential diagnosis. Cancer Surv 1985;4:349–58. 30. Wood KM, Pallesen G, Ralfkiaer E, Warnke R, Gatter K, Mason DY. Heterogeneity of CD3 antigen expression in T-cell lymphoma. Histopathology 1993;22:311–7. 31. de Mascarel A, Merlio JP, Coindre JM, Goussot JF, Broustet A. Gastric large cell lymphoma expressing cytokeratin but no leukocyte common antigen. A diagnostic dilemma. Am J Clin Pathol 1989;91:478–81. 32. Frierson HF Jr, Bellafiore FJ, Gaffey MJ, McCary WS, Innes DJ Jr, Williams ME. Cytokeratin in anaplastic large cell lymphoma. Mod Pathol 1994;7:317–21. 33. Lasota J, Hyjek E, Koo CH, Blonski J, Miettinen M. Cytokeratinpositive large-cell lymphomas of B-cell lineage. A study of five phenotypically unusual cases verified by polymerase chain reaction. Am J Surg Pathol 1996;20:346–54. 34. McCluggage WG, el-Agnaff M, O’Hara MD. Cytokeratin positive T cell malignant lymphoma. J Clin Pathol 1998;51: 404–6. 35. Menestrina F, Lestani M, Scarpa A, et al. Common acute lymphoblastic leukaemia–lymphoma expressing cytokeratin: a case report. Virchows Arch 1994;425:83–7.

General Introduction

36. Friedman HD, Tatum AH. HMB-45-positive malignant lymphoma. A case report with literature review of aberrant HMB45 reactivity. Arch Pathol Lab Med 1991;115:826–30. 37. Fung CH, Antar S, Yonan T, Lo JW. Actin-positive spindle cell lymphoma. Arch Pathol Lab Med 1993;117:1053–5. 38. Lertprasertsuke N, Tsutsumi Y, Maruyama T. B-cell lymphoma with vimentin-positive cytoplasmic inclusions. Acta Pathol Jpn 1991;41:473–9. 39. Fraternali-Orcioni G, Falini B, Quaini F, et al. Beta-HCG aberrant expression in primary mediastinal large B-cell lymphoma. Am J Surg Pathol 1999;23:717–21. 40. Warnke RA, Rouse RV. Limitations encountered in the application of tissue section immunodiagnosis to the study of lymphomas and related disorders. Hum Pathol 1985;16:326–31. 41. Herman GE, Elfont E. Aberrant CD45 (Leucocyte common antigen) staining of non-malignant breast lesions in zinc formalin fixed tissue. J Histotechnol 1993;16:151–3. 42. Nandedkar MA, Palazzo J, Abbondanzo SL, Lasota J, Miettinen M. CD45 (leukocyte common antigen) immunoreactivity in metastatic undifferentiated and neuroendocrine carcinoma: a potential diagnostic pitfall. Mod Pathol 1998;11:1204–10. 43. Strauchen J. Diagnostic Histopathology of the Lymph Node. New York: Oxford University Press, 1998.

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2

Reactive and Infective Conditions

Reactive lymph node changes are typically classified either by the predominant site in the node which is expanded or by the aetiology of the change. Table 2.1 attempts to summarise these changes using both features. It is important to understand that lymph nodes react as organic structures and that none of these changes should be considered in isolation. In other words, all the structures frequently undergo changes and the suggested categorisation refers only to the predominant changes.

Follicular hyperplasia Non-specific In most cases follicular hyperplasia is characterised by a lymph node that has gradually enlarged over weeks or months and for which there is usually no obvious clinical diagnosis. The lymph node is hence biopsied more than anything to eliminate a diagnosis of malignancy [1]. Follicular hyperplasia (Fig 2.1) is characterised by an increase in the number and size of follicles, so it is a hypertrophic as well as a hyperplastic event. The structure of the node is maintained and the capsule is usually intact. The germinal centres are the main site of this change with increased numbers of mitoses and ‘tingible body’ macrophages (these are large macrophages phagocytosing apoptotic nuclear debris). Typically the mantle zones remain intact and follicles are separated by at least a small sliver of paracortex. The size of the follicles may be quite variable and, although they are typically round, a number of odd shapes including dumb-bells and balloons may be seen. Note that some follicles can be seen in the pericapsular adipose tissue. The main differential diagnosis is with follicular lymphoma. Reactive follicles are polyclonal, have a high proliferation rate and are bcl-2 protein negative. Further practical details of this distinction are in Chapter 12.

Toxoplasmosis Lymphadenitis may occur after primary infection with the protozoan Toxoplasma gondii, caught apparently from domestic cat faeces or eating infected meat. The clinical features are highly variable, ranging from solitary lymphadenopathy with no symptoms through a self-limiting infectious mononucleosis-like condition to a life-threatening systemic disease with encephalitis and myocarditis. The latter is more likely to arise in an immunodeficient host. Histologically toxoplasmosis is characterised by three features [2,3]. These are prominent follicular hyperplasia, epithelioid histiocytes in small collections (‘epithelioid congeries’), often hanging on to the mantle zones like limpets, and sinuses packed with monocyte-like cells (monocytoid B lymphocytes) (Fig 2.2). Monocytoid B cells are often accompanied by small numbers of neutrophils. These cells were initially designated as immature sinus histiocytes but immunostaining studies have identified them as mature B cells. Although these are characteristic if not diagnostic of toxoplasmosis, monocytoid B lymphocytes filling the sinuses can be observed in lymphadenitis of other aetiologies, e.g. cytomegalovirus (CMV). The parasite is rarely found in lymph nodes even by the polymerase chain reaction (PCR) so that the diagnosis requires serological antibody studies to be confirmed [4].

Leishmaniasis Visceral or systemic leishmaniaisis, also known as kala-azar, is rare in the west. Biopsies of infected organs may include the spleen, lymph node, liver and bone marrow. Usually there is an extensive population of macrophages full of the typical ‘safety pin-like’ amastigotes. Regional lymph node involvement in cutaneous leishmaniasis may be more subtle, with changes very similar to toxoplasmosis although usually the granulomas are bigger and careful inspection reveals the presence of amastigotes (Fig 2.3).

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Table 2.1 Reactive and infective conditions Follicular hyperplasia Non-specific Toxoplasmosis Castleman disease Rheumatoid arthritis Syphilis Kimura disease Measles Progressive transformation of germinal centres HIV Paracortical expansion Most viral lymphadenopathy especially Epstein–Barr virus Kikuchi disease Lupus Typhoid Dermatopathic Drug induced Sinus hyperplasia: Sinus histiocytosis Rosai–Dorfman disease Lymphangiography effect and silicon deposition Granulomatous conditions: Tuberculosis and leprosy Sarcoidosis Cat-scratch fever and lymphogranuloma venereum Fungal Lipidoses and other depositions

Castleman disease This is an unusual follicular hyperplasia of unknown aetiology [5]. It is usually divided into two categories – hyaline– vascular type and plasma cell variant – although there is overlap between them, with some authorities describing mixed or transitional forms.

Hyaline–vascular type This usually occurs as a solitary enlarged lymph node commonly in the mediastinum (where it was originally described [6]) in young patients with no other symptoms. It may occur in extranodal sites including lung and soft tissues. It is worth checking for the presence of follicular dendritic cell sarcoma because a few cases have been associated with the features of Castleman disease. Excision of the lymph node is usually curative. The histology is characterised by increased numbers of small follicles (Fig 2.4). Closer inspection shows that most of these have the germinal centre replaced by a thick-walled blood vessel, around which are clustered a few B cells and follicular dendritic reticulum cells, sometimes showing a concentric arrange-

Reactive and Infective Conditions

ment mimicking Hassall’s bodies. Some atypical large cells with bizarre nuclei corresponding to FDCs are commonly observed, and some of these may be quite large with bizarre nuclei and have been confused with the tumour giant cells of Hodgkin lymphoma (Fig 2.5). The interfollicular area shows increased numbers of thickwalled, high endothelial venules surrounded by a mixture of plasma cells (but not in sheets) and lymphocytes, sometimes accompanied by small clusters of plasmacytoid dendritic cells (Fig 2.6). Immunostaining can be helpful in identifying the abnormal FDCs (CD21, CNA-42) or the plasmacytoid dendritic cells (CD68 or CD123), both of which can occasionally give rise to diagnostic concern. However, these dysplastic FDCs may label poorly with the usual FDC markers. More recent studies of plasmacytoid monocytes have suggested they are differentiating more towards dendritic cells than mature macrophages. This is based on their positivity for recently described markers such as bcl11a, CD123 and CD2AP [7]. These are more commonly associated with dendritic cells than macrophages. Plasmacytoid monocytes/ dendritic cells are frequently seen in other specific reactive conditions, including Kikuchi disease and lupus lymphadenitis, but do occur occasionally in many other reactive conditions, including in nodes draining tumours where care needs to be taken not to mistake them for metastases (Fig 2.7).

Plasma cell variant This variant occurs in two forms: localised disease and multicentric or systemic Castleman disease. The localised form usually occurs in younger adults, particularly in mediastinal or abdominal lymph nodes. In contrast to the hyaline vascular variant, these patients usually present with symptoms such as fever, anaemia and hypergammaglobulinaemia. However, similar to hyaline vascular Castleman disease excision is often curative. The histology of the plasma cell variant is characterised by confluent sheets of either monoclonal (usually λ) or polyclonal plasma cells in the interfollicular areas [8–10]. Follicular hyperplasia is prominent but, unlike hyaline vascular Castleman disease, many if not all of the follicles are quite ordinary with typical germinal centres rather than all showing hyaline vascular change (Fig 2.8).

Multicentric or systemic Castleman disease This disorder affects older patients. They present with widespread lymphadenopathy, often with accompanying hepatosplenomegaly. They are usually quite ill with a variety of severe systemic symptoms. In particular some have a characteristic constellation of features known as the POEMS syndrome. This acronym stands for polyneuropathy, organomegaly, endocrine abnormalities, monoclonal gammopathy and skin rashes). These patients are immunodeficient

21

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Reactive and Infective Conditions

H&Es

CD20

CD10

Proliferation

FDCs

DBA-44

bcl-2

Fig 2.1 Reactive follicular hyperplasia contains typical germinal centres composed of centroblasts and centrocytes with admixed tingible body macrophages being prominent. They are well circumscribed, a feature often best seen by immunostaining for B cell antigens such as CD20. Germinal centres have a high proliferation rate (Ki67 antigen) which is often zoned reflecting the light and dark zones seen on the H&E stain. The follicular dendritic cell meshwork (FDCs) is regular (CD21 positive) and follicles are often CD10 positive but bcl-2 protein negative. Mantle zones have a different phenotype from the germinal centre and can be highlighted with markers such as IgD or DBA.44.

22

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Reactive and Infective Conditions

CD20

CD68

Fig 2.2 The major features of toxoplasmosis are illustrated using haematoxylin and eosin (H&E) and by immunostaining. The ‘monocytoid B cells in the sinuses’ are indicated with white arrows and shown at high power (bottom left), whereas the epithelioid congeries or microgranulomas in their typical parafollicular (and occasionally germinal centre) positions are shown by black arrows. *Germinal centres.

CD20

CD68

23

CHAPTER 2

Reactive and Infective Conditions

Fig 2.3 Lymph nodes in leishmaniasis, especially the cutaneous variety, may show follicular hyperplasia with surrounding granulomatous lesions. Within these amastigotes can usually be found in the epithelioid macrophages.

CD20

Castleman disease: hyaline vascular type CD21

Fig 2.4 The hyaline–vascular subtype of Castleman disease is composed of atrophic B-cell follicles in which the germinal centres have become progressively vascularised. This change in the germinal centre is often best highlighted by immunostaining for follicular dendritic cells (FDCs), e.g. with CD21. The dendritic cell processes may also form rings that probably account for the onion skin appearance of mantle lymphocytes around some of the follicles. These vascularised follicles are surrounded by a hyalinised or highly vascular paracortex.

24

CHAPTER 2

and prone to severe infections and have a raised incidence of developing lymphoma or Kaposi sarcoma. The 5-year survival rate is less than 50%. Many cases of multicentric Castleman disease occur in HIV-positive patients and all of these are also positive for human herpesvirus 8 (HHV8) [11–13]. In HIV-negative

Reactive and Infective Conditions

Castleman disease of whatever type, a varying proportion of cases has been reported to express HHV8 preferentially in subcapsular spindle cells [14]. A number of these cases of HHV8 multicentric Castleman disease go on to develop a characteristic plasmablastic large-cell lymphoma, which has recently been recognised by the World Health Organization (WHO) as a separate subentity of diffuse large B-cell lymphoma (Fig 2.9).

Rheumatoid arthritis Most patients with rheumatoid arthritis develop lymphadenopathy at some stage in their disease. This may be either localised or systemic. The latter is particularly common with Still disease or juvenile rheumatoid arthritis. Patients with rheumatoid arthritis have an increased risk of developing lymphomas, especially follicular lymphoma. Even so the incidence is quite low and should not be overdramatised [15]. Although about 25% of patients with T-cell large granular lymphocyte leukaemia have rheumatoid arthritis, this lymphoma is rare. Controversy continues over whether it is rheumatoid arthritis itself that is the risk factor for lymphoma or the treatments meted out to these patients, including drugs such as methotrexate and gold [16]. The histology is one of florid follicular hyperplasia [17] and indeed the nodes can be enormous. Often there is a marked polyclonal plasmacytosis in the paracortical regions (Fig 2.10). Clusters of neutrophils may also be prominent, particularly in nodes that are in the region of active joint inflammation. The pathology can be complicated by the development of amyloidosis in longstanding sufferers.

Syphilis

Fig 2.5 Examples of the pleomorphic morphology of FDCs (black arrows) that may be seen in and around the nodules of hyaline–vascular subtype of Castleman disease.

Lymphadenopathy arising from Treponema pallidum infection is often also rather quaintly referred to as luetic lymphadenitis. Enlarged lymph nodes are really only a feature of the primary and secondary stages. Most patients are now diagnosed clinically so that lymph node biopsies for syphilis

CD68 Fig 2.6 Plasmacytoid monocytes are a typical feature of Castleman disease of hyaline vascular subtype. They consist, as shown, of clusters of small cells (arrowed) with abundant cytoplasm and a lymphoid nuclear morphology. Originally thought to be a T-cell variant, histiocytic immunostains such as CD68 clearly identify them as being of monocytic lineage derived from plasmacytoid dendritic cells.

25

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Reactive and Infective Conditions

Fig 2.7 Typical example of plasmacytoid monocytes/dendritic cells seen in a reactive node draining a breast cancer. Any doubts as to their nature can be resolved by showing their positivity for CD68 (KP1 or PGM1 (middle left and centre) and their negativity for myeloperoxidase (middle right), CD3, CD20 and CD21 (bottom left to right).

26

CHAPTER 2

Reactive and Infective Conditions

VS38

CD34

κ

CD79a

λ Fig 2.8 In the plasma cell variant of Castleman disease only a proportion of the follicles (example shown with antibody CD34 in insert) show the vascularised morphology seen in the hyaline vascular variant. A variety of different follicles is illustrated here with both H&E and the B-cell marker CD79a. Plasma cells are prominent in the interfollicular area (highlighted by antibody VS38) and may be polyclonal (as shown here) or monoclonal (usually λ).

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Reactive and Infective Conditions

CD34

HHV8

CD34 + HHV8

Fig 2.9 Immunostains for CD34 and human herpesvirus 8 (HHV8) show that a proportion of cells surrounding the follicles are HHV8+. Double staining indicates that these are not of vascular origin.

chetes can be detected by silver staining though most patients are in fact diagnosed serologically.

Kimura disease

Fig 2.10 Florid follicular hyperplasia as seen in rheumatoid arthritis.

would be taken these days only by mistake. The disease is also not as common as it was so most currently practising haematopathologists will have seen few, if any, examples. There are two main patterns described [18]. One is florid follicular hyperplasia with sheets of interfollicular polyclonal plasma cells, which makes the plasma cell variant of Castleman disease the most likely differential diagnosis. The second is marked paracortical expansion with immunoblasts and plasma cells as seen in many viral infections. Associated changes are many and varied including endarteritis, granulomatous inflammation and necrosis. If suspected the spiro-

28

This is a rare inflammatory disorder typically affecting lymph nodes and soft tissues of the head and neck in young males. There is a great predominance of cases in Asian and Oriental populations [19]. Histologically the lymph nodes are characterised by follicular hyperplasia with an associated paracortical hyperplasia. It is this that is diagnostic, being composed of a proliferation of thin-walled blood vessels surrounded by masses of eosinophils (Fig 2.11). Many cases of Kimura disease will also show masses of eosinophils in germinal centres accompanied by necrosis, ‘eosinophilic folliculolysis’. It is often emphasised that Kimura disease should not be confused with angiolymphoid hyperplasia with eosinophilia [20,21]. This is not always as easy as some authorities make out. In general angiolymphoid hyperplasia is a haemangiomatous reaction in the subcutaneous tissues of the head and neck. It is characterised by thick-walled masses of vessels which, although accompanied by eosinophils, are not massed in clusters as with Kimura disease (Fig 2.12). Involvement of lymph nodes is rare but when present makes the differential from Kimura disease more difficult. Furthermore, angiolymphoid hyperplasia occurs as commonly in western as in Oriental populations and is, if anything, more common in women than in men. The aetiology of this condition is unknown.

CHAPTER 2

Reactive and Infective Conditions

CD15

Fig 2.11 Kimura disease is characterised by reactive follicles separated by an angiolymphoid proliferation with many clustered eosinophils. These are highlighted by the CD15 immunostain.

Measles

Progressive transformation of germinal centres

Lymphadenopathy is common in measles infections but is rarely biopsied because the disease is diagnosed clinically. Dr Strauchan, in his excellent account of reactive viral lymphadenitis, says: ‘Lymph node biopsy during the prodromal phase may permit the pathologist to make a diagnosis of probable measles before the appearance of the characteristic exanthem, thereby gaining great credit amongst his clinical colleagues!’ [22]. Alas for the current authors because we have signally failed to achieve this, but the point is well made. Measles-affected lymph nodes are usually large with florid follicular hyperplasia. The large germinal centres contain characteristic multinucleated forms of dendritic reticulum cells known as Warthin–Finkeldey cells. Such cells are also seen in other reactions, especially in HIV infections and in some lymphomas, but rarely are there as many as in measles (Fig 2.13).

Progressive transformation of germinal centres may occur as an isolated event in many different types of reactive follicular hyperplasia. However, the term is generally used as a diagnosis when they are plentiful and are scattered throughout nodes alongside typical reactive germinal centres. This tends to occur in children and young adults [23,24]. It is relatively frequent in association with nodular lymphocytepredominant Hodgkin lymphoma where it may occur before, during or after the diagnosis [25–27]. Progressive transformation of germinal centres describes a changed pattern in the relationship of the mantle zone and germinal centre in hyperplastic follicles. The name refers to the apparent progressive infiltration of the germinal centre with mantle zone cells, leading to a blurring of the two in an apparently jumbled manner (Fig 2.14). Aggregates of germinal centre cells are better seen after immunostaining. They are negative for bcl-2 and strongly positive for Ki-67.

29

CD31 In lymph node

In soft tissue

CNA42

Fig 2.12 Angiolymphoid hyperplasia occurs mostly in soft tissues and only rarely in lymph nodes. It differs from Kimura disease in not being associated with follicular hyperplasia, possessing thick-walled vessels and without large numbers of eosinophils.

Fig 2.13 Measles lymphadenopathy is characterised by follicular hyperplasia with giant syncytial follicular dendritic cells known as Warthin–Finkeldy cells. These can be definitely identified as such with antibodies against follicular dendritic cells such as CD21 or CNA42 (as illustrated here).

CHAPTER 2

Reactive and Infective Conditions

Fig 2.14 Two typical examples of lymph nodes involved by significant numbers of progressively transformed germinal centres. Note that they do not involve the whole node and have many different architectural patterns.

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Expanded mantle zone lymphocytes are highlighted by their strong positive staining for IgD or DBA-44 (Fig 2.15). The process is benign and resolves of its own accord although it may recur. There has been much discussion of its relationship to nodular lymphocyte-predominant Hodgkin lymphoma with the current consensus being that, although associated, there is no relationship to the development or recurrence of nodular lymphocyte-predominant Hodgkin lymphoma. It is important to distinguish progressive transformation of germinal centres from definite nodular lymphocytepredominant Hodgkin lymphoma. This can be very challenging diagnostically. In general progressive transformation of germinal centres does not involve the whole node; involved follicles are intermixed with normal secondary follicles and tend not to be surrounded by small clusters of epithelioid macrophages and lack characteristic lymphocytepredominant (LP) cells. In contrast, the nodules of nodular lymphocyte-predominant Hodgkin lymphoma typically form a mass lesion within the node, often surrounded by a small rim of normal uninvolved lymph node which may contain one or more progressively transformed follicles. The larger blast cells seen in progressive transformation of germinal centres are usually not seen outside the nodules, are CD10 positive, and are neither rosetted by CD57-positive T cells nor epithelial membrane antigen (EMA) positive. That said, most experienced haematopathologists can relate one or two borderline cases where, by Murphy’s law, they jumped the wrong way and regretted it. In other words at times one should be brave enough to admit that a distinction is not possible and seek another opinion or write a suitably contrite report. Occasionally the transformed germinal centres may be so filled with bcl2-positive mantle cells and T cells that the possibility of follicular lymphoma is raised. Here the key to diagnosis is to assess the whole immunophenotypic picture that so characterizes follicular lymphoma which usually clearly enables a distinction to be made (see Chapter 12).

IgD CD20

IgD

bcl-2

CD21

CD3

HIV Many cases of lymphadenopathy occurring in relationship to HIV infection are caused by specific infections or malignancies. In the absence of any cause other than HIV there is a syndrome of reactive lymphadenopathy called persistent generalised lymphadenopathy [28]. This has a clinical definition as lymph node enlargement of more than 3 months’ duration at two or more sites other than inguinal regions with no demonstrable aetiology other than HIV [29]. The histological appearances are typically those of extremely florid follicular hyperplasia with many bizarrely shaped germinal centres. A common feature is the presence of follicle lysis where the germinal centre looks as though it has exploded out into the rest of the node (Fig 2.16).

32

Proliferation Fig 2.15 Immunophenotyping shows that progressively transformed germinal centres are large secondary B-cell follicles (CD20) with abundant follicular dendritic cell meshworks (CD21) and a great increase in the mantle zone (IgD, bcl-2). Their proliferation rate (Ki67) is high, reflecting their origin from reactive germinal centres.

CHAPTER 2

Reactive and Infective Conditions

Fig 2.16 A selection of bizarre follicles showing the appearances of follicle lysis in HIV-related lymphadenopathy.

33

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Reactive and Infective Conditions

CD79a

CD3

IgD

p24

CD21

Fig 2.17 The lysis of HIV-infected follicles is often best appreciated by immunostaining. The mantle zones (IgD) are profoundly disrupted with a prominent infiltration of T cells (CD3) into the germinal centre. Inside the germinal centre the HIV-related p24 antigen is prominently displayed on follicular dendritic cells (FDCs) and macrophages. Note how disrupted the FDC meshwork is (CD21). Contrast these appearances with those of progressively transformed germinal centres discussed previously and it is obvious how different they are.

This is often best appreciated by inspecting the FDC stains where the FDC meshwork is broken up into little packets apparently floating in a sea of small lymphocytes (Fig 2.17). Indeed at times this may be the first presentation of otherwise unsuspected HIV infection and other confirmatory investigations can then be undertaken. It should be noted that follicle lysis occurs in other reactive nodes too and is not specific for HIV lymphadenopathy [30]. Immunostaining for the HIV p24 antigen will confirm the diagnosis, although pathologists should take advice before undertaking what is in essence an HIV test because local ethical regulations on this will vary. As the disease progresses

34

into AIDS this lymphadenopathy is either complicated by infection or malignancy or starts to undergo involution, so that terminally the nodes are almost empty with atrophic involuted follicles which are often vascularised giving a Castleman disease-like appearance (Fig 2.18). Indeed as mentioned previously coinfection with HHV8 multicentric Castleman disease is a common condition in HIV infection (Fig 2.19). The most common infectious agents seen in association with HIV are the so-called opportunistic ones including Mycobacterium tuberculosis and M. avian-intracellulare (Fig 2.20), fungi especially Histoplasma, Cryptococcus, Toxoplasma

CHAPTER 2

"Burn out"

Involution Fig 2.18 Some complications of HIV associated lymphadenopathy.

and Pneumocystis spp. Coexisting malignancies in HIV-related lymphadenopathy are typically either Kaposi sarcoma (which may be focal and easily overlooked) and aggressive non-Hodgkin lymphomas (see Fig 2.18).

Paracortical expansion Viral lymphadenopathy especially Epstein–Barr virus infection Lymphadenopathy is a common feature in many viral illnesses but the diagnosis is so obvious clinically that biopsies are not commonly taken. This has two consequences: most haematopathologists have limited experience of these lesions and are often not expecting such a diagnosis. The biopsies typically come from young people with persistent lymphadenopathy being treated by experienced clinicians who feel that malignancy is a likely diagnosis. Occasionally tonsillectomy is performed because of asphyxia due to tonsillar swelling. The majority of viruses (measles being a major exception – see above) produce marked paracortical expansion in

Reactive and Infective Conditions

which many large blast cells (often described as immunoblasts) are scattered (Fig 2.21). Abnormal forms and in particular Reed–Sternberg-like cells may occur but they are not usually numerous. Follicles do occur but rarely is there an associated follicular hyperplasia [32]. Immunostains usually show that the blasts are a mixture of B and T cells – indeed in EBV infection most may be of B-cell type (Fig 2.22). Viral antigens such as LMP (latent membrane protein) for EBV or CMV associated can be detected in some of these cells. Some of the blasts may be CD30 positive but they are typically negative for CD15 and EMA [33](Fig 2.23). Note that, Reed-Sternberg-like cells in these lesions are LMP1+ and EBNA2+ whereas in EBVpositive Hodgkin lymphoma, Reed–Sternberg cells are LMP1+ but EBNA2− [34]. CMV infection also gives rise to a paracortical expansion very similar to that seen with EBV (Fig 2.24). However, it should be noted that with both EBV and CMV the earliest changes are in fact a follicular hyperplasia, with monocytoid B-cell hyperplasia similar to that seen with toxoplasmosis. Depending on local clinical thresholds for biopsy different haematopathology services will see more early or late cases. Often, if a hospital has a large transplant service, there is a low threshold for biopsy leading to more cases showing follicular rather than paracortical expansion.

Herpes lymphadenitis Herpetic lymphadenitis frequently involves inguinal lymph nodes [35,36]. Typical cutaneous lesions are usually found in the genital area either at diagnosis or after the lymph node biopsy [36]. Generalised lymphadenopathy may occur [37]. Rare cases of acute necrotising tonsillitis have also been reported [38]. Herpes lymphadenopathy may occur in patients with chronic lymphocytic leukaemia (CLL) or other low-grade lymphomas/leukaemias [39–41]. Indeed any area of necrosis in a lymph node involved by CLL should raise suspicion for herpes. The recognition of herpes simplex virus (HSV) lymphadenitis is important because of the availability of an effective anti-herpetic therapy (aciclovir). However, patients with CLL and associated herpes often do well without specific antiviral therapy. Nodal changes consist of necrotising lymphadenitis and proliferation of immunoblasts with plasma cells [35,36]. A large number of immunoblasts in the setting of CLL may raise concern for progression (the Richter transformation). Close inspection on high power examination shows diagnostic intranuclear inclusions associated with peripheral chromatin. Infected cells are easily detectable with immunostaining with an anti-HSV antibody that reacts with antigens common to HSV-1 and -2 (Fig 2.25). These cells appear to be restricted to the necrotic areas.

35

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Reactive and Infective Conditions

ZN

Tuberculosis

Kaposi sarcoma Fig 2.19 The number of tubercle bacilli seen in HIV-associated cases is variable. Sometimes they are plentiful and clumped and at other times single and scattered as shown. It is worth noting that opportunistic infections in lymph nodes may be associated with Kaposi sarcoma (shown here in the subcapsular sinus at three different powers) and/or Hodgkin lymphoma [31]. ZN, Ziehl–Neelsen stain.

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Reactive and Infective Conditions

As a result of the presence of neutrophils in necrotic areas, cat-scratch disease is a possible differential diagnosis but the palisading histiocytes surrounding these are missing in herpetic lymphadenitis. Herpetic lymphadenitis may also simulate the lymph node changes seen in systemic lupus erythematosus or Kikuchi disease. However, in contrast to these lesions, the necrotic areas in herpetic lymphadenitis are usually rich in neutrophils.

Kikuchi disease

ZN

Kikuchi disease is a benign self-limiting necrotising lymphadenitis typically seen in young Oriental individuals especially females [42,43]. Patients are typically unwell for some weeks or months with prominent unilateral cervical lymphadenopathy. The lymph nodes may be painful and are often accompanied by fever, leukopenia and sometimes skin rashes. A few cases have developed a haemophagocytic syndrome. Most patients recover without treatment although a few have relapses. Only one fatality has been recorded (from myocarditis) [44]. It is believed to be of viral origin although this is as yet unproven. The histology is typical with loose granulomatous nodules in the paracortex, composed of a mixture of macrophages some of which have crescent-shaped nuclei, a typical feature of this condition [45,46] (Fig 2.26). Other macrophages have a variety of cytological features, some of which may be quite blastic, causing concern about a lymphoma. Lymphocytes and granulocytes are rare within these lesions. Usually the centre of the nodule is necrotic but this is not invariable. All these features add up to one of the alternative names for this condition – ‘necrotising lymphadenitis without neutrophil polymorphs’. Immunostains are very helpful in confirming the histiocytic nature of the process with B and T cells being rare in the lesions, although there may be residual B-cell follicles surrounding them (Fig 2.27). Occasionally there is a surprising number of T cells, many of which are CD8+, which may cause concerns about a T-cell lymphoma (although CD8+ peripheral T-cell lymphomas are not so common). These are also not usually the large pleomorphic cells in the lesions but, in case of doubt, PCR for T-cell rearrangement should be requested. A proportion of the histiocytes is also myeloperoxidase positive which is very useful as a final confirmation of diagnosis [47].

Lupus lymphadenitis

CD68 Fig 2.20 In HIV infection the reaction of histiocytes to an overwhelming infection of atypical mycobacteria (ZN stain) can give rise to a sarcomatous reaction as illustrated. The histiocytic response is demonstrated by CD68 staining.

Lymphadenitis associated with SLE (systemic lupus erythematosus) is not common and usually occurs when the clinical syndrome is manifest and the diagnosis obvious. However, the histology of lupus lymphadenitis is very similar to that seen in Kikuchi disease (Fig 2.28). In fact it is so similar that many have speculated that they are at two ends of a clinical spectrum. The literature on the comparisons of these conditions is confusing but in general it seems that

37

Fig 2.21 This is an example of an HIV-related plasma cell variant of Castleman disease complicated by focal collections of Kaposi sarcoma. In the upper row both features can be seen in the low power view on the left, with higher power views of the Kaposi sarcoma in the middle and the plasma cell-rich Castleman disease on the right. The plasma cells are highlighted by antibody VS38 in the lower row left, with HHV8 staining of the Kaposi sarcoma and next to it adjacent ‘normal vessels’ (both shown in the middle lower panel), with the typical vascularisation of the follicles detailed by the antibody CD34 on the lower right.

Fig 2.22 Epstein–Barr virus infection typically causes a pure paracortical expansion, although a few large follicles may be present. The infiltrate consists of a mixture of blast cells and other reactive cell types. The blast cells are usually immunoblastic in cytology, although some may have a ‘Reed–Sternberglike’ appearance (black arrows).

EBV

CD20

CD30

CD3

CD8

LMP

EBER

Fig 2.23 Immunophenotype of Epstein–Barr virus (EBV) infection. The infiltrate is a mixture of B- and T-blast cells, the latter being predominantly CD8+. Some of the blasts are also CD30+ (any Reed–Sternberg-like cells are CD20+, CD30+ but CD15−). EBV can usually be demonstrated by immunostaining for LMP (latent membrane protein) or in situ for EBER (EBV RNA). Sometimes only the latter is positive.

Fig 2.24 Cytomegalovirus (CMV) infection is another less common infectious cause of paracortical expansion. The appearances may be similar to Epstein–Barr virus (EBV) infection but its nature can be confirmed by immunostaining for CMV antigens (far right figure). These lesions are almost always associated with a severe immunodeficiency.

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Fig 2.25 Herpetic lymphadenitis is characterised by necrotic areas surrounded by plasma cells and immunoblasts. Within the necrotic areas are the infected cells seen in H&E with their inclusions and characteristic marginated nuclear chromatin (upper figures with high power insert). These cells are clearly highlighted by immunostaining with an anti-herpes antibody (lower figures).

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Fig 2.26 The low-power views at the top of this figure show the loosely cohesive granulomatous lesions, some with and some without necrosis seen in Kikuchi disease lymphadenitis. At higher power in the lower row, the characteristic macrophages with crescentic nuclei and the admixture of other blastic cells are evident. Note the high amount of apoptotic debris that is characteristic of this disorder. Indeed such abundant apoptotic debris is seldom seen in lymphomas with which Kikuchi disease may be confused.

there are more neutrophil polymorphs and fewer CD8+ T cells in SLE, although estimating these in practice can be extremely subjective [48]. Plasma cells may be prominent in SLE and less conspicuous in Kikuchi disease. Occasionally, too clear evidence of vasculitis can be seen in affected lymph nodes which is rather rare in Kikuchi disease lymphadenitis. The presence of so-called haematoxylin bodies in the necrotic areas is also helpful because these at best are rare in Kikuchi disease lymphadenitis. These are small purple bodies seen both extracellularly and in macrophages in the necrotic areas.

Typhoid lymphadenitis Lymph nodes are rarely biopsied in this condition but, when they are, they show many features that remind one of Kikuchi disease lymphadenitis. In typhoid, however, the mononuclear phagocytes are even more prominent and may form well-circumscribed nodules (Fig 2.29). Within and around these infiltrates areas of necrosis are commonly seen. Further similarities with Kikuchi disease have been shown by J Chan (personal communication), in that these mononuclear macrophages are also positive for myeloperoxidase.

Dermatopathic lymphadenopathy Dermatopathic lymphadenopathy is a common cause of lymph node enlargement distal to chronic skin conditions which may be either inflammatory or neoplastic, especially mycosis fungoides. Lymph nodes show very characteristic focal areas of pale cells in the paracortex. The paleness is caused by an accumulation of dendritic cells of both Langerhans and interdigitating types. Admixed are variable numbers of lymphocytes and macrophages, some of which may contain melanin pigment, a characteristic feature of this lesion. Immunocytochemistry is helpful by showing that these pale cells are S100 protein, CD1a and CD207 (Langerin) positive [49] (Fig 2.30). In patients with mycosis fungoides it can be difficult to distinguish early infiltration from the reactive dendritic cells. T-cell gene rearrangement studies suggest that most patients with mycosis fungoides and dermatopathic lymphadenopathy do in fact have lymph node involvement that is just difficult to detect morphologically. As the mycosis progresses of course the lymph node involvement becomes increasingly obvious [50,51]. As neoplastic cells in mycosis fungoides have a tendency to lose the CD7 T-cell-associated antigen, the demonstration of a CD3+,

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CD20

CD68

myeloperoxidase Fig 2.27 Immunostaining for B-cell antigens (CD20) shows the paracortical nature of this disorder. Macrophage markers such as CD68 highlight the nodules as histiocytic in nature. In Kikuchi disease these macrophages are characteristically positive for myeloperoxidase which can be very useful in identifying this disorder. Plasmacytoid dendritic cells are also increased and may be numerous in this disorder. These cells can be specifically labelled by newer markers such as CD123 or bcl11a.

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Fig 2.28 This case came from a lymph node biopsy of a patient with severe systemic lupus erythematosus (SLE) taken to exclude associated malignancy. It shows significant areas of necrosis looking very similar to Kikuchi disease lymphadenitis (H&E at low power on top left). This similarity extends to the general lack of neutrophils and other lymphocytes, with the predominant cells being macrophages positive for CD68 (bottom left) and many crescentic and mononuclear forms being myeloperoxidase positive (bottom middle left). However, a careful search revealed evidence of vasculitis (top middle left) shown rather more clearly by CD31 immunostaining (left panel). The high-power haematoxylin and eosin (H&E)-stained image demonstrates the presence of haematoxylin bodies (right panel).

CD7− T-cell population is suggestive of neoplastic involvement of a lymph node.

Sinus hyperplasia

Drug-induced lymphadenopathy

Sinus histiocytosis

A long list of drugs can give rise to the syndrome of druginduced lymphadenopathy, of which phenytoin is the best known and most reported, although increasing numbers of cases are arising in patients treated with methotrexate for autoimmune disorders such as rheumatoid arthritis. The lymphadenopathy usually occurs within weeks of starting the drug, and typically is part of a constellation of systemic symptoms including fevers and skin rashes. Lymph node enlargement may occur in isolation, when it can be tricky to distinguish from lymphomas and as such has often acquired the label ‘pseudolymphoma’. A typical case shows marked paracortical expansion composed of a mixture of small-to-medium-sized reactive T cells admixed with polymorphic B-blast cells (Fig 2.31). The latter can be very abnormal and at times resemble Reed–Sternberg cells. The key to the diagnosis is that the proliferation does not destroy the underlying lymph node architecture and does not really look like any definite lymphoma subtype. When there is genuine doubt PCR for B- and T-cell gene rearrangements can be helpful. Excluding classic Hodgkin lymphoma is more testing because, although the blast cells express a full B-cell phenotype with CD30 and lack CD15, this can be seen on genuine cases of Hodgkin lymphoma too. Caution and careful clinicopathological discussions are needed.

This is a very common reaction pattern in lymph nodes draining a distant infection or tumour. The sinuses become dilated and filled with bland and unremarkable macrophages, few if any of which contain phagocytosed material (Fig 2.32). When examining such nodes draining cancers one needs to look carefully to ensure that small numbers of metastatic cells are not overlooked. Occasionally especially in children the sinuses can be filled with macrophages laden with red cells (and other cell types) as part of a presumed virally induced haemophagocytic syndrome [52] (Fig 2.33). This condition usually presents in the bone marrow and, by the time lymph nodes or spleen are involved, the prognosis is grave. There is now growing evidence implicating EBV in the pathogenesis of this condition [53].

Rosai–Dorfman disease This is also known as sinus histiocytosis with massive lymphadenopathy (SHML) [54]. It presents typically in children and adolescents with extensive painless bilateral cervical lymphadenopathy, often associated with other extranodal involvement in the skin, lung, gut, bone or brain. Systemic symptoms are common and include fever, anaemia, raised white cell counts and a polyclonal hypergammaglobulinaemia. Although generally benign, the course is often long and

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CD68

Myeloperoxidase

Fig 2.29 In typhoid lymphadenitis there is a prominent infiltration of mononuclear macrophages forming nodular aggregates in areas. These may be associated with areas of necrosis. The immunophenotype of these macrophages is very similar to that seen in Kikuchi disease lymphadenitis being CD68 and myeloperoxidase positive. (Courtesy of Dr J Chan, Hong Kong.)

44

S100

CD1a

CD1a

Fig 2.30 Dermatopathic lymphadenopathy has a characteristic low-power appearance of paracortical expansion caused by the proliferation of interdigitating/Langerhans cells. These are clearly seen at higher powers, with elongated twisted nuclei interspersed with melanin-containing macrophages (black arrow). They are also visible in subcapsular sinuses (second row right), presumably coming in from the draining skin. Immunostaining shows the characteristic phenotype of S100 and CD1a positivity. CD207 (Langerin) gives very similar results to CD1a indicating that either can be used reliably for diagnosis [49].

45

Fig 2.31 Drug-induced lymphadenopathy associated with methotrexate treatment of rheumatoid arthritis. The HEs at different powers on the top row show the paracortical expansion of the node by a polymorphic collection of lymphoid cells. Immunostains for CD3 (bottom left at low and high power) show a proliferation of reactive T cells, with the larger blast cells being of B-cell (CD20+) origin (bottom right at low and high power).

H&E

CD68

Fig 2.32 Two examples of sinus histiocytosis with the macrophages highlighted in the sinuses by CD68 immunostaining

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around these invaginated cells. The rest of the lymph node is usually unremarkable, although there are huge numbers of plasma cells and some areas of fibrosis as well as capsular fibrosis. Immunostains for histiocytic markers such as CD68 may be useful to identify the enlarged cells as macrophages [55,56]. These cells also stain for S100 protein but are CD1a negative. An S100 stain can be very helpful for highlighting the emperipolesis (Fig 2.34).

Lymphangiography effect and silicon deposition Insoluble oils and foreign materials such as silicon may cause significant and dramatic sinus histiocytosis when they leak into the tissues. This may be deliberate as in the injection of iodised oils for diagnostic lymphangiograms (Fig 2.35) or by accident when a silicon-based implant leaks (Fig 2.36). If the source of the material is removed these lesions usually remit on their own, although there has been considerable speculation about long-term toxicity, especially with regard to leaking implants. A number of other foreign materials may accumulate in lymph nodes including tattoo pigments, polyvinylpyrrolidone (PVP) (which is contained in a number of drugs) and products derived from surgical material such as cellulose from the degradation of gauze inadvertently left behind after an operation.

Tattoos

Fig 2.33 Haemophagocytic syndrome showing red cell-laden macrophages in the sinuses of lymph node (top left) and spleen (top right), with a higher power view in the top centre. Immunostaining for CD68 (bottom with insert) demonstrates the histiocytic nature of these phagocytes and shows that the red cells are within these cells.

Inks and pigments from tattoos always leak into the lymphatics and may cause confusion with the diagnosis when lymph nodes are biopsied for other reasons. Indeed the accumulation of pigment in histiocytes may itself give rise to lymphadenopathy. The trick when faced with apparent black carbon deposits in lymph nodes (other than pulmonary of course) is to look for evidence of coloured pigments usually green, blue or turquoise. These are practically diagnostic of tattoos (Fig 2.37).

Granulomatous conditions relapsing and many forms of therapy (mostly without success) have been tried to stop or ameliorate this. A small percentage of cases end in death usually by infection resulting from immunosuppression. Histologically the nodes are characterised by the sinuses being grossly dilated by huge numbers of large macrophages, often with foamy cytoplasm. The histiocytes typically have vesicular nuclei that have a thin nuclear membrane and prominent nucleoli. Their cytoplasm may be filled with lymphocytes and occasionally other cells such as polymorphs or plasma cells. These are not being phagocytosed but are just invaginated into the cytoplasm, a process called emperipolesis (often displayed by megakaryocytes in the bone marrow in a variety of reactive settings). There is often a clear space

Tuberculosis Mycobacterium tuberculosis is extremely widespread as an infectious agent throughout the world and is re-emerging as a cause of lymphadenopathy in western countries due to HIV infection, homelessness and intravenous drug use. Atypical forms, especially Mycobacterium avium-intracellulare, are also becoming more common in AIDS patients. Tuberculosis is characterised by multiple well-formed granulomas arising in the interfollicular areas but progressively crushing the rest of the node [57]. The granulomas are foci of epithelioid histiocytes with Langhans-type giant cells often surrounded by a collar of T cells. B-cell follicular remnants can usually be appreciated only by immunostaining. The centre of the granulomas may be necrotic (caseous

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nodal

CD68

CD45 GI tract Fig 2.34 Two cases of nodal and one of extranodal Rosai–Dorfman disease. The masses of enlarged macrophages through which lymphoid cells are passing are clearly visible. They may be more dramatically illustrated by immunostaining for macrophages with CD68 or with lymphoid markers such as CD45, the leukocyte common antigen.

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lymph node

CD68 Spleen

CD68 Fig 2.35 Oil-based contrast dyes used to be employed routinely for lymphangiography in the staging of Hodgkin lymphoma and gave rise to the florid sinus histiocytosis seen in this figure.

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CD68 Fig 2.36 Similar appearances to those of a lymphangiogram are more commonly seen today in axillary lymph nodes draining a leaking breast implant.

necrosis) and the numbers of organisms are usually small and have to be searched for carefully. Atypical tuberculosis, on the other hand, may have few granulomatous areas with the lymph nodes often replaced by diffuse sheets of epithelioid histiocytes, with few giant cells and little or no necrosis [22]. In contrast to classic tuberculosis acid-fast bacilli are very numerous in the histiocytes and can often be appreciated on the routine stains alone (Fig 2.38).

Leprosy Although an important condition in developing countries, especially in rural parts of India, leprosy lymphadenitis is rarely encountered in the west. There are two forms of the disease, which each give a different picture in lymph nodes. Lepromatous leprosy causes lymphadenopathy by expanding the interstitial areas with large numbers of foamy mac-

50

rophages. in which acid-fast leprosy bacilli can often be identified (Fig 2.39). Tuberculoid leprosy simulates tuberculosis with large areas of epithelioid granulomas, although unlike tuberculosis necrosis is uncommon. Leprosy bacilli are rarely identified in this form of the disease.

Sarcoidosis Sarcoidosis is a relatively uncommon granulomatous disorder of mysterious origins, although there are marked differences of incidence in different geographical regions. In the USA, it is especially prevalent in young black women [58]. Any organ may be involved but lungs and lymph nodes (especially those in the mediastinum and pulmonary hilum) are the most common. The course of the disease is highly variable and, although most run a relatively benign course, some patients end up with progressive pulmonary fibrosis [59].

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weeks, lymphadenopathy occurs in the draining area. This is often associated with systemic symptoms such as fever. The condition is usually self-limiting and resolves over a further period of weeks. It is a bacterial infection caused by Bartonella henselae [60] which can sometimes be detected by silver staining, although they are very small and indistinct and the number of organisms is generally low in most biopsied nodes. Serology and/or PCR is currently the most reliable method of confirming this diagnosis, although a recently described monoclonal antibody working well on paraffin sections looks very promising [61] (Fig 2.41). Lymph nodes are usually biopsied when the condition has been present for some time. In these cases the typical pathological features of large perifollicular or paracortical suppurative granulomas or stellate microabscesses are seen [62]. These contain purulent material rich in polymorphs and are surrounded by a so-called palisade of histiocytes. At this stage organisms are very rarely seen by silver staining. As a result of this, in those cases where the polymorphs are scarce, the appearances can closely mimic tuberculosis and great care is needed in establishing the correct diagnosis. If the lymph node is biopsied early on in the process, the features are purely those of a non-specific reactive follicular hyperplasia. Now the organisms are often numerous and readily detectable if the condition is considered in the differential diagnosis (Fig 2.42).

Fig 2.37 Typical appearances of a tattoo in a lymph node with the sinusoidal localisation of the pigments within macrophages. Note, at higher power in the insert and below, the different coloured pigments used.

Sarcoidosis typically replaces the tissue or lymph node with multiple interlocking granulomas usually without any evidence of true caseation, although foci of central necrosis (often showing fibrin-like structures) are reasonably frequent. Multinucleate giant cells are present and often contain characteristic inclusions that are star shaped (asteroid bodies) or round (Schaumann bodies), although these are not specific for this disease. These granulomas are almost always surrounded by dense fibrosis (hyaline sclerosis) (Fig 2.40). Sarcoidosis, except in areas with a high incidence, remains a diagnosis of exclusion. The full range of infective and neoplastic conditions that can give rise to granulomatous inflammation should be excluded alongside careful clinical liaison before the diagnosis is accepted.

Cat-scratch fever This disease is caused, just as its name says, by cat (or more often kitten) scratches. Some time later, which may be

Lymphogranuloma venereum Lymphogranuloma venereum is caused by the sexually transmitted bacterium Chlamydia trachomatis. The inguinal lymphadenopathy is normally preceded by genital cutaneous rashes and ulcers. Systemic symptoms such as fevers and myalgias are common. The lymph node pathology is indistinguishable from late cat-scratch fever so that, if the diagnosis is not obvious clinically, the distinction needs to be made by serology or PCR testing for the relevant organisms.

Whipple disease (intestinal lipodystrophy) This chronic disease is not restricted to the bowel. Mesenteric and even peripheral lymphadenopathy is common. The lymph nodes are enlarged due to distended sinuses which may simulate a lymphangiogram effect, in particular on frozen section examination. Characteristically there is an accumulation of macrophages that usually predominates in the lymph node pulp close to sinuses. These histiocytes show epithelioid features and epithelioid granulomas may be present. As seen in jejunal biopsy specimens, the cytoplasm of histiocytes contains large amounts of periodic acid– Schiff (PAS)-positive lipids (Fig 2.43). These bacilliform bodies are believed to belong to the bacterium Tropheryma whipplei, although this still needs to be to be formally confirmed.

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caseous necrosis

ZN

CD68

CD20 ZN

AIDs related Fig 2.38 The top two rows show the appearances of tuberculosis in an immunocompetent individual. Granulomas are typically associated with multinucleate giant cells (black arrow) and caseous necrosis (white arrow). Staining for the B-cell marker CD20 shows the paracortical location and CD68 immunostaining confirms the histiocytic nature of the granulomas. Acid-fast bacilli are few in number (Ziehl–Neelsen stain). In immunodeficient individuals (bottom row) such as in those with AIDS the picture is different. Granulomas are less defined, lack necrosis and giant cells, and acid-fast bacilli are numerous.

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Fig 2.39 Lepromatous leprosy showing the interstitial infiltration at low power (top left) of foamy eosinophilic macrophages (top right and bottom left). An acid-fast (Fite-Faraco) stain shows numerous intracellular bacteria. (Courtesy of Professor R. Dorfman, Stanford, USA.)

Fungal Lymphadenitis arising from fungal infection is usually associated with immunosuppression from HIV, malignancy or chemotherapy. The features seen depend somewhat on the severity of the immunodeficiency. If this is relatively mild (or in the rare normal host) a typical granulomatous inflammatory response with central necrosis and giant cells may be seen. In contrast, severely immunodeficient patients may just have a node replaced by diffuse sheets of macrophages and lymphocytes associated with huge numbers of fungi. The most common agents are histoplasma and cryptococci, both of which are readily demonstrable with silver or PAS stains in lymph nodes, both granulomatous and diffuse.

Lipidoses and other depositions These are all very rare conditions affecting lymph nodes and include Gaucher and Niemann–Pick diseases. When encoun-

tered the lymph node sinuses are filled with large lipidcontaining macrophages which may coalesce to give a granuloma-like reaction. The diagnosis is most likely to have been made clinically or on a bone marrow biopsy already. Other depositions that may give granuloma-like reactions include amyloidoisis and a variety of other proteins and foreign body materials.

Lymph node inclusions such as nevus cell inclusion Inclusions in the capsules of lymph nodes can be very disconcerting when other diagnoses are being considered. The two most common ones are accumulations of nevus cells and ectopic localisation of salivary (in neck) or mammary (axillary) glands. All of these can be misdiagnosed if one neglects to consider that malignant cells really do not localise exclusively in the capsule (Fig 2.44).

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Reactive and Infective Conditions

CD20

Fig 2.40 Many of the features of sarcoidosis are similar to tuberculosis but granulomas are usually smaller without necrosis. Once again the location is paracortical (white arrow and CD20). As the disease develops the lymph node may become progressively hyalinised (black arrow). CD68 defines the granulomas as histiocytic in origin.

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Late form

CD68

CD15

Early form

CD15

CD20

CD68

Fig 2.41 The most common picture of cat-scratch disease encountered in practice is that seen in the late form on the left. Here the large stellate granulomas are composed of a rim of macrophages (CD68) surrounding a suppurative centre filled with necrotising macrophages and polymorphs (CD15). Below are the features seen in early stages of the disease, where the picture is largely that of non-specific follicular hyperplasia. Careful analysis with immunostains will often show the developing granulomas (CD15). In the bottom row monocytoid B cells are illustrated accumulating in the subcapsular sinuses. This feature is of course most commonly seen in toxoplasmosis.

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Fig 2.42 It is now possible to immunostain for Bartonella henselae reliably in paraffin sections.

Fig 2.44 Benign glandular inclusions in an axillary lymph node that should not be mistaken for malignant deposits.

References

Fig 2.43 Case of Whipple disease in the lymph node showing the sinusoidal localisation of the granulomas (H&E above) which consist of periodic acid–Schiff (PAS)-positive histiocytes (bottom left) within which PAS-positive bacilliform figures can be seen (bottom right).

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13. Brousset P, Cesarman E, Meggetto F, Lamant L, Delsol G. Colocalization of the viral interleukin-6 with latent nuclear antigen-1 of human herpesvirus-8 in endothelial spindle cells of Kaposi’s sarcoma and lymphoid cells of multicentric Castleman’s disease. Hum Pathol 2001;32:95–100. 14. O’Leary J, Kennedy M, Howells D, et al. Cellular localisation of HHV-8 in Castleman’s disease: is there a link with lymph node vascularity? Mol Pathol 2000;53:69–76. 15. Isomaki HA, Hakulinen T, Joutsenlahti U. Excess risk of lymphomas, leukemia and myeloma in patients with rheumatoid arthritis. J Chronic Dis 1978;31:691–6. 16. Georgescu L, Quinn GC, Schwartzman S, Paget SA. Lymphoma in patients with rheumatoid arthritis: association with the disease state or methotrexate treatment. Semin Arthritis Rheum 1997;26:794–804. 17. Kondratowicz GM, Symmons DP, Bacon PA, Mageed RA, Jones EL. Rheumatoid lymphadenopathy: a morphological and immunohistochemical study. J Clin Pathol 1990;43:106–13. 18. Hartsock RJ, Halling LW, King FM. Luetic lymphadenitis: a clinical and histologic study of 20 cases. Am J Clin Pathol 1970; 53:304–14. 19. Hui PK, Chan JK, Ng CS, Kung IT, Gwi E. Lymphadenopathy of Kimura’s disease. Am J Surg Pathol 1989;13:177–86. 20. Googe PB, Harris NL, Mihm MC. Kimura’s disease and angiolymphoid hyperplasia with eosinophilia: two distinct histopathological entities. J Cutan Pathol 1987;14:263–71. 21. Chan JK, Hui PK, Ng CS, Yuen NW, Kung IT, Gwi E. Epithelioid haemangioma (angiolymphoid hyperplasia with eosinophilia) and Kimura’s disease in Chinese. Histopathology 1989;15: 557–74. 22. Strauchen J. Diagnostic Histopathology of the Lymph Node. New York: Oxford University Press, 1998. 23. Ferry JA, Zukerberg LR, Harris NL. Florid progressive transformation of germinal centers. A syndrome affecting young men, without early progression to nodular lymphocyte predominance Hodgkin’s disease. Am J Surg Pathol 1992;16:252–8. 24. Osborne BM, Butler JJ, Gresik MV. Progressive transformation of germinal centers: comparison of 23 pediatric patients to the adult population. Mod Pathol 1992;5:135–40. 25. Burns B, Colby T, Dorfman R. Differential diagnostic features of nodular L&H Hodgkin’s disease, including progressive transformation of germinal centers. Am J Surg Pathol 1984;8: 253–61. 26. Poppema S, Kaiserling E, Lennert K. Hodgkin’s disease with lymphocytic predominance, nodular type (nodular paragranuloma) and progressively transformed germinal centres–a cytohistological study. Histopathology 1979;3:295–308. 27. Crossley B, Heryet A, Gatter KC. Does nodular lymphocyte predominant Hodgkin’s disease arise from progressively transformed germinal centres? A case report with an unusually prolonged history. Histopathology 1987;11:621–30. 28. Metroka CE, Cunningham-Rundles S, Pollack MS, et al. Generalized lymphadenopathy in homosexual men. Ann Intern Med 1983;99:585–91. 29. Center for Control of Diseases. Persistent generalised lymphadenopathy among homosexual males. MMWR 1982;31:249–51. 30. Guettier C, Gatter KC, Heryet A, Mason DY. Dendritic reticulum cells in reactive lymph nodes and tonsils: an immunohistological study. Histopathology 1986;10:15–24.

Reactive and Infective Conditions

31. Brousset P, Marchou B, Chittal SM, Delsol G. Concomitant Mycobacterium avium complex infection and Epstein–Barr virus associated Hodgkin’s disease in a lymph node from a patient with AIDS. Histopathology 1994;24:586–8. 32. Strickler JG, Fedeli F, Horwitz CA, Copenhaver CM, Frizzera G. Infectious mononucleosis in lymphoid tissue. Histopathology, in situ hybridization, and differential diagnosis. Arch Pathol Lab Med 1993;117:269–78. 33. Abbondanzo SL, Sato N, Straus SE, Jaffe ES. Acute infectious mononucleosis. CD30 (Ki-1) antigen expression and histologic correlations. Am J Clin Pathol 1990;93:698–702. 34. Salvador AH, Harrison EG, Kyle RA. Lymphadenopathy due to infectious mononucleosis: its confusion with malignant lymphoma. Cancer 1971;27:1029–40. 35. Gaffey MJ, Ben-Ezra JM, Weiss LM. Herpes simplex lymphadenitis. Am J Clin Pathol 1991;95:709–14. 36. Miliauskas JR, Leong AS. Localized herpes simplex lymphadenitis: report of three cases and review of the literature. Histopathology 1991;19:355–60. 37. Tamaru J, Mikata A, Horie H, et al. Herpes simplex lymphadenitis. Report of two cases with review of the literature. Am J Surg Pathol 1990;14:571–7. 38. Wat PJ, Strickler JG, Myers JL, Nordstrom MR. Herpes simplex infection causing acute necrotizing tonsillitis. Mayo Clin Proc 1994;69:269–71. 39. Doody MM, Linet MS, Glass AG, et al. Leukemia, lymphoma, and multiple myeloma following selected medical conditions. Cancer Causes Control 1992;3:449–56. 40. Higgins JP, Warnke RA. Herpes lymphadenitis in association with chronic lymphocytic leukemia. Cancer 1999;86:1210–5. 41. Mariette X, Molina JM, Asli B, Brouet JC. A patient with chronic lymphoid leukemia and recurrent necrotic herpetic lymphadenitis. Am J Med 1999;107:403–4. 42. Kikuchi M. Lymphadenitis showing focal reticulum cell hyperplasia with nuclear debris and phagocytes. Acta Hematol Jpn 1972;35:379–80. 43. Pileri S, Kikuchi M, Helbron D, Lennert K. Histiocytic necrotizing lymphadenitis without granulocytic infiltration. Virchows Arch A Pathol Anat Histol 1982;395:257–71. 44. Chan JK, Wong KC, Ng CS. A fatal case of multicentric Kikuchi’s histiocytic necrotizing lymphadenitis. Cancer 1989; 63:1856–62. 45. Rivano MT, Falini B, Stein H, et al. Histiocytic necrotizing lymphadenitis without granulocytic infiltration (Kikuchi’s lymphadenitis). Morphological and immunohistochemical study of eight cases. Histopathology 1987;11:1013–27. 46. Tsang WY, Chan JK, Ng CS. Kikuchi’s lymphadenitis. A morphologic analysis of 75 cases with special reference to unusual features. Am J Surg Pathol 1994;18:219–31. 47. Pileri S, Facchetti F, Ascani S, et al. Myeloperoxidase expression by histiocytes in Kikuchi’s and Kikuchi-like lymphadenopathy. Am J Pathol 2001;159:915–24. 48. Hu S, Kuo TT, Hong HS. Lupus lymphadenitis simulating Kikuchi’s lymphadenitis in patients with systemic lupus erythematosus: a clinicopathological analysis of six cases and review of the literature. Pathol Int 2003;53:221–6 49. Lau SK, Chu PG, Weiss LM. Immunohistochemical expression of Langerin in Langerhans cell histiocytosis and non-Langerhans cell histiocytic disorders. Am J Surg Pathol 2008;32:615–19.

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50. Weiss LM, Hu E, Wood GS, et al. Clonal rearrangements of T-cell receptor genes in mycosis fungoides and dermatopathic lymphadenopathy. N Engl J Med 1985;313:539–44. 51. Weiss LM, Wood GS, Warnke RA. Immunophenotypic differences between dermatopathic lymphadenopathy and lymph node involvement in mycosis fungoides. Am J Pathol 1985; 120:179–85. 52. Risdall RJ, McKenna RW, Nesbit ME, et al. Virus-associated hemophagocytic syndrome: a benign histiocytic proliferation distinct from malignant histiocytosis. Cancer 1979;44: 993–1002. 53. Gaffey MJ, Frierson HF Jr, Medeiros LJ, Weiss LM. The relationship of Epstein–Barr virus to infection-related (sporadic) and familial hemophagocytic syndrome and secondary (lymphomarelated) hemophagocytosis: an in situ hybridization study. Hum Pathol 1993;24:657–67. 54. Rosai J, Dorfman RF. Sinus histiocytosis with massive lymphadenopathy. A newly recognized benign clinicopathological entity. Arch Pathol 1969;87:63–70. 55. Sacchi S, Artusi T, Torelli U, Emilia G. Sinus histiocytosis with massive lymphadenopathy. Leuk Lymphoma 1992;7:189–94.

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56. Eisen RN, Buckley PJ, Rosai J. Immunophenotypic characterization of sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease). Semin Diagn Pathol 1990;7:74–82. 57. Dandapat MC, Mishra BM, Dash SP, Kar PK. Peripheral lymph node tuberculosis: a review of 80 cases. Br J Surg 1990; 77:911–2. 58. Newman LS, Rose CS, Maier LA. Sarcoidosis. N Engl J Med 1997;336:1224–34. 59. Barnard J, Newman LS. Sarcoidosis: immunology, rheumatic involvement, and therapeutics. Curr Opin Rheumatol 2001; 13:84–91. 60. Adal KA, Cockerell CJ, Petri WA. Cat scratch disease, bacillary angiomatosis, and other infections due to Rochalimaea. N Engl J Med 1994;330:1509–15. 61. Cheuk W, Chan AK, Wong MC, Chan JK. Confirmation of diagnosis of cat scratch disease by immunohistochemistry. Am J Surg Pathol 2006;30:274–5. 62. Ferry J, Harris N. Atlas of Lymphoid Hyperplasia and lymphoma. Philadelphia: WB Saunders, 1997.

3

An Introduction to Lymphoma Diagnosis

In the last few decades lymphoma classification has been parodied mercilessly as captured in the wisecrack ‘only three things are certain in life: birth, death and changes in lymphoma classification’. That has now changed with the publication of the REAL classification [1] and its general acceptance into the current World Health Organization (WHO) classification of lymphoid neoplasms (Table 3.1) [2]. This puts lymphoma classification on a firm basis of diagnosing clinical entities using all of the available data as required, and this approach is taken throughout this book. Clinical studies to date show that this approach is helpful and reliable [3,4]. This text does not dwell further on the background to the so-called ‘lymphoma wars’ because there are several good references available for those interested [5–8]. The only aspect worth emphasising is that one of the major strengths of the REAL and WHO classifications is the flexibility to incorporate new data and to make changes, as most recently shown in the 2008 version of the WHO classification [9]. Pathologists should never again try to have almost biblical allegiances to one or other guru’s views but to judge issues on the facts or the ‘data set’ as it is now often called.

of different entities. Although there is variability around the world, the non-Hodgkin lymphoma classification project set up to evaluate the REAL classification in the mid-1990s enlisted eight centres from different areas [4]. This allowed one of the best bird’s-eye views of relative numbers of lymphomas available. Basically only eight entities made it above 2% with any of the others being extremely rare (Table 3.2). Subsequent analyses by different lymphoma groups have broadly agreed with this project; occasionally Burkitt and lymphoblastic lymphoma make it above the 2% waterline and are added below. This means that familiarity with 10 reasonably straightforward entities (peripheral T cell being a possible exception) will enable any pathologist to deal with the bulk of his or her work in lymphoid neoplasms. It would be quite reasonable to send the rest (±10% of the workload) for consultation to the most accessible and amenable expert. This, of course, depends on the conditions and requirements in different countries, which is a matter currently under debate in several. If money were no object there might be a specialist haematopathologist for every 1000 or so lymphoid biopsies per annum who would not need this book anyway! However, we are writing this for the real world so will dwell no longer with the fairies.

The relative frequency of the different lymphomas Some of the sting is taken out of the complexity of lymphoma diagnosis when one looks at the relative frequency

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Table 3.1 The WHO classification of lymphoid and related malignancies Precursor lymphoid neoplasms B-lymphoblastic leukemia/lymphoma B-lymphoblastic leukemia/lymphoma, not otherwise specified B-lymphoblastic leukemia/lymphoma with recurrent genetic abnormalities B-lymphoblastic leukemia/lymphoma with t(9;22)(q34;q11.2); BCR-ABL1 B-lymphoblastic leukemia/lymphoma with t(v;11q23); MLL rearranged B-lymphoblastic leukemia/lymphoma with t(12;21)(p13;q22); TEL-AML1 (ETV6-RUNX1) B-lymphoblastic leukemia/lymphoma with hyperdiploidy B-lymphoblastic leukemia/lymphoma with hypodiploidy (hypodiploid ALL) B-lymphoblastic leukemia/lymphoma with t(5;14)(q31;q32); IL3-IGH B-lymphoblastic leukemia/lymphoma with t(1;19)(q23;p13.3); E2A-PBX1; (TCF3-PBX1) T-lymphoblastic leukemia/lymphoma Mature B-cell neoplasms Chronic lymphocytic leukemia/small lymphocytic lymphoma B-cell prolymphocytic leukemia Splenic marginal zone lymphoma Hairy cell leukemia Splenic lymphoma/leukemia, unclassifiable Splenic diffuse red pulp small B-cell lymphoma Hairy cell leukemia – variant Lymphoplasmacytic lymphoma Waldenström macroglobulinemia Heavy chain diseases α heavy chain disease γ heavy chain disease μ heavy chain disease Plasma cell myeloma Solitary plasmacytoma of bone Extraosseous plasmacytoma Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) Nodal marginal zone lymphoma Pediatric nodal marginal zone lymphoma Follicular lymphoma Pediatric follicular lymphoma Primary cutaneous follicle center lymphoma Mantle cell lymphoma Diffuse large B-cell lymphoma (DLBCL) and variants Diffuse large B-cell lymphoma (DLBCL), not otherwise specified T-cell/histiocyte-rich large B-cell lymphoma Primary DLBCL of the CNS Primary cutaneous DLBCL, leg type EBV-positive DLBCL of the elderly DLBCL associated with chronic inflammation Lymphomatoid granulomatosis Primary mediastinal (thymic) large B-cell lymphoma Intravascular large B-cell lymphoma ALK-positive DLBCL Plasmablastic lymphoma Large B-cell lymphoma arising in HHV8-associated multicentric Castleman disease Primary effusion lymphoma Burkitt lymphoma B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and classic Hodgkin lymphoma

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Table 3.1 (continued) Mature T-cell and NK cell neoplasms T-cell prolymphocytic leukemia T-cell large granular lymphocytic leukemia Chronic lymphoproliferative disorder of NK cells Aggressive NK cell leukemia Systemic EBV-positive T-cell lymphoproliferative disease of childhood Hydroa vaccineforme-like lymphoma Adult T-cell leukemia/lymphoma Extranodal NK/T-cell lymphoma, nasal type Enteropathy-associated T-cell lymphoma Hepatosplenic T-cell lymphoma Subcutaneous panniculitis-like T-cell lymphoma Mycosis fungoides Sézary syndrome Primary cutaneous CD30+ T-cell lymphoproliferative disorders Lymphomatoid papulosis Primary cutaneous anaplastic large cell lymphoma Primary cutaneous γ/δ T-cell lymphoma Primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma Primary cutaneous CD4+ small/medium T-cell lymphoma Peripheral T-cell lymphoma, not otherwise specified Angio-immunoblastic T-cell lymphoma Anaplastic large cell lymphoma, ALK positive Anaplastic large cell lymphoma, ALK negative Hodgkin lymphoma Nodular lymphocyte-predominant Hodgkin lymphoma Classic Hodgkin lymphoma Nodular sclerosis classic Hodgkin lymphoma Lymphocyte-rich classic Hodgkin lymphoma Mixed cellularity classic Hodgkin lymphoma Lymphocyte-depleted classic Hodgkin lymphoma Histiocytic and dendritic cell neoplasms Histiocytic sarcoma Langerhans cell histiocytosis Langerhans cell sarcoma Interdigitating dendritic cell sarcoma Follicular dendritic cell sarcoma Fibroblastic reticular cell tumor Indeterminate dendritic cell tumor Disseminated juvenile xanthogranuloma Other blastic disorders Myeloid sarcoma Blastic plasmacytoid dendritic cell neoplasm Post-transplant lymphoproliferative disorders (PTLD) Early lesions Plasmacytic hyperplasia Infectious mononucleosis-like PTLD polymorphic PTLD monomorphic PTLD (B- and T/NK- cell types) Classic Hodgkin lymphoma type PTLD

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Table 3.2 The frequency of different lymphoma subtypes seen in clinical practice Lymphoma type

Frequency (%)

Diffuse large B cell Follicular Marginal zone lymphoma Peripheral T cell Chronic lymphocytic leukaemia Mantle cell lymphoma Mediastinal B cell Anaplastic large cell Burkitt lymphoma Lymphoblastic lymphoma

31 22 8 7 7 6 2 2 2 2

References 1. Harris NL, Jaffe ES, Stein H, et al. A revised European–American classification of lymphoid neoplasms: a proposal from the International Lymphoma Study Group [see comments]. Blood 1994;84:1361–92.

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2. Swerdlow SH, Campo E, Harris NL, et al., eds. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 4th edn. Lyon: IARC Press, 2008. 3. Melnyk A, Rodriguez A, Pugh WC, Cabannillas F. Evaluation of the Revised European–American Lymphoma classification confirms the clinical relevance of immunophenotype in 560 cases of aggressive non-Hodgkin’s lymphoma. Blood 1997;89:4514–20. 4. The Non-Hodgkin’s Lymphoma Classification Project. A clinical evaluation of the International Lymphoma Study Group classification of non-Hodgkin’s lymphoma. Blood 1997;89:3909–18. 5. Mason DY, Gatter KC. Not another lymphoma classification! Br J Haematol 1995;90:493–7. 6. Mason D, Gatter K. The Pocket Guide to Lymphoma Classification. Oxford: Blackwells, 1998. 7. Isaacson PG. The current status of lymphoma classification. Br J Haematol 2000;109:258–66. 8. Mason D, Harris N, eds. Human Lymphoma: Clinical implications of the REAL classification. London: Springer, 1999. 9. Jaffe ES. The 2008 WHO classification of lymphomas: implications for clinical practice and translational research. Hematology Am Soc Hematol Educ Program 2009: 523–31.

4

B-cell Lymphoblastic Leukaemia/Lymphoma

This is a blastic proliferation of precursor B cells that may produce a tissue infiltration (lymphoma), and involve blood and bone marrow (leukaemia–acute lymphoblastic leukaemia [ALL]) or both. A figure of 25% blasts in the bone marrow is often used as the clinical criterion for the definition of ALL.

Clinical features B-lymphoblastic neoplasms most commonly present in childhood as common acute lymphoblastic leukaemia. Presentations as lymphoma are infrequent but most often involve skin, bone or lymph node and may occur at any age.

Histology Lymphoblastic lymphoma/leukaemia consists of mediumsized cells with scanty cytoplasm, most of the cell being occupied by the nucleus (Fig 4.1). These have a primitive structure with very fine chromatin and several small nucleoli, often described as ‘salt and pepper like’ in appearance. Although typically thought of as a monotonous infiltration, it is often surprising how pleomorphic these nuclei can be. Typically, tissues are just overwhelmed by the infiltration, although sometimes a pattern of single cell infiltration is seen which is reminiscent of that seen in lobular carcinoma of the breast. Mitoses are common and areas of necrosis and starry sky macrophages may be seen.

Blood involvement Blasts cells in the blood and bone marrow are commonly seen in the course of most lymphoblastic lymphomas. In fact, the cut-off between lymphoma and leukaemia is quite arbitrary, with some paediatric oncology groups considering only neoplasms with more than 25% bone marrow infiltra-

tion as leukaemia whereas anything less than 10% blast cells in the blood of adults is a lymphoma [1,2].

Immunophenotype B lymphoblasts have a characteristic phenotype of positivity for TdT (terminal deoxynucleotidyl transferase), CD10, CD19, CD22, CD43, PAX5 and CD79a (Table 4.1 and Fig 4.2). About 50% of cases are also positive for CD34(3). CD45 is often weak or absent, especially in paraffin sections. Of note in paraffin section studies is that the commonly used B-cell marker, CD20, is absent in approximately 50% of cases. Proliferation markers such as Ki67 show a high growth fraction, but with rarely more than 70–80% of cells positive. Increasing numbers of bi- or multiphenotypic acute leukaemias are being described as larger series of cases are being immunotyped. Cases of acute leukaemia with both B-cell and myeloid markers, including myeloperoxidase and CD117 (cKIT), are not infrequent and lesions sharing B- and T-cell antigens have been described [4,5]. Some of these cases are probably better placed in the new World Health Organization (WHO) category of acute leukaemias of ambiguous lineage, although there continues to be too little information about these cases to know whether they are or are not genuinely distinct entities.

Cytogenetics Cytogenetic abnormalities can be detected in most cases though they are quite variable and cover a wide range of different chromosomes. As denoted in the 2008 WHO classification, a number of cases of B-lymphoblastic leukaemia/ lymphoma with recurrent genetic abnormalities are recognized as a distinct subcategory, mainly because they have distinct prognostic implications [6–9]. Briefly these can be described as follows.

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Low power

High power

Giemsa

Fig 4.1 Both Giemsa and haematoxylin and eosin (H&E) stains show the typical infiltrative pattern of small- to medium-sized blastic cells. The higher powers show the typical pleomorphism of the blasts on histology that sometimes surprises those used to seeing them in cytological preparations such as blood or bone marrow smears.

H&E

Table 4.1 Comparison of the immunophenotypes of B-lymphoblastic lymphoma with its main differential diagnoses

B lymphoblastic T lymphoblastic Mantle cell blastic Acute myeloid leukaemia

CD20

CD79a

PAX5

CD3

CD5

CD10

TdT

CD34

Cyclin D1

± − + ±

+ ± + ±

+ − + ±

− + − −

− + + −

+ + − −

+ + − ±

± ± − ±

− − + −

Poor prognosis • B-lymphoblastic leukemia/lymphoma with t(9;22) (q34;q11.2); BCR-ABL1 • B-lymphoblastic leukemia/lymphoma with t(v;11q23); MLL rearranged • B-lymphoblastic leukemia/lymphoma with hypodiploidy (hypodiploid ALL).

Good prognosis • B lymphoblastic leukemia/lymphoma with t(12;21) (p13;q22); TEL-AML1 (ETV6-RUNX1) • B lymphoblastic leukemia/lymphoma with hyperdiploidy.

These cases are usually identified by cytogeneticists using standard karyotyping or fluorescent in situ hybridisation (FISH) techniques. For the pathologist they look identical to other B-lymphoblastic leukemia/lymphoma cases and have the same immunophenotype. A possible clue to B-lymphoblastic leukemia/lymphoma with t(v;11q23); MLL rearranged is that, unlike the other cytogenetic variants and most other standard cases, it is generally CD10−. Most cases of lymphoblastic B-cell lymphoma show immunoglobulin heavy chain rearrangement and a significant number also show T-cell γ gene rearrangement [10,11].

Unchanged prognosis • B-lymphoblastic leukemia/lymphoma (q31;q32); IL3-IGH • B-lymphoblastic leukemia/lymphoma (q23;p13.3); E2A-PBX1; (TCF3-PBX1).

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with

t(5;14)

Differential diagnosis

with

t(1;19)

On morphological grounds alone, a number of tumours may mimic lymphoblastic B-cell lymphoma.

CHAPTER 4

CD79a

B-cell Lymphoblastic Leukaemia/Lymphoma

CD20

CD10

CD34

TdT

Proliferation

Fig 4.2 The typical and characteristic immunophenotype of B-lymphoblastic lymphoma. All cases are CD79a, CD10 and TdT positive, but only half show staining for CD20 (a positive and a negative case are illustrated here) and/or CD34. Staining for proliferation-associated markers such as Ki67 is often surprisingly low for such an aggressive tumour. The example shown here is only about 50% positive.

T-cell lymphoblastic lymphoma (see Chapter 5) In common with B-cell lymphoblastic lymphoma, these neoplasms are almost always positive for TdT and express CD10 and CD43 antigens. Approximately 40–50% of these tumours also express the ‘B-cell’ antigen CD79a [12,13]. However, the expression of CD3, often in association with other T-cell antigens (CD1a, CD2, CD4, CD5, CD8), is indicative of the T-cell origin of the tumour because B-cell lymphoblastic lymphomas do not express CD3. These coexpressing tumours also show T-cell gene rearrangements rather than immunoglobulin gene rearrangements [14].

Blastoid variant of mantle cell lymphoma (see Chapter 13) Mantle cell lymphoma usually consists of small- to mediumsized cells with characteristic hyperchromatic cleaved nuclei. However, the lymphoblastoid variant of these tumours may be extremely difficult to recognise and is easily misdiagnosed as lymphoblastic lymphoma. In the blastoid variant of mantle cell lymphoma, the malignant cells express CD20, CD79a, CD43 and CD5 antigens, but are best identified by nuclear positivity for cyclin D1 [15]. In contrast to lymphoblastic lymphomas these tumours are negative for TdT, CD10 and CD34 antigens.

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Burkitt lymphoma (see Chapter 15)

Other lymphomas

These tumours express IgM (most easily demonstrated on frozen sections) and most B-cell-associated antigens such as CD20 and CD79a. The malignant cells are also positive for CD10 and often CD43, but negative for CD34, TdT, bcl-2 and T-cell-associated antigens. In addition these tumours are strongly positive for CD45 antigen and have a proliferation rate close to 100%.

Depending on the circumstances it is possible to confuse virtually any other lymphoma type with lymphoblastic type, but two others worth mentioning are CLL (chronic lymphocytic leukaemia/lymphoma) and diffuse large B-cell lymphoma. These suggestions may raise a few eyebrows compared to the more obvious ones above but it is surprising how CLL can seem ‘blastic’ and how often diffuse large B-cell lymphoma is composed of cells that really do not look so large (see discussion in Chapter 14). The key is to diagnose lymphoblastic lymphoma with caution in elderly people and to perform a complete immunophenotype if there is any element of doubt.

Blastic plasmacytoid dendritic cell neoplasm (see Chapter 29) This new entity in the 2008 WHO Classification primarily involves the skin and is easily confused with lymphoblastic lymphoma, especially as many cases are TdT+ [16–18]. In these neoplasms the blastic cells are negative for B- and T-cell antigens and express CD4, CD43, CD56, CD68 and plasmacytoid dendritic cell antigens such as CD123 and bcl11a [19].

Myeloblastic tumours/acute myeloid leukaemia (see Chapter 32) Distinguishing myeloblastic proliferations from lymphoblastic lymphomas can be difficult, particularly in the case of

HE

HE

HE

CD79a

CD7

bcl2

CD117 (cKIT)

CD117 (cKIT)

TdT

Fig 4.3 An example of a challenging lymph node biopsy in a 16-year-old girl. The node is replaced by relatively pleomorphic blast cells (H&E) that are CD45+, CD79a+, CD7+ and bcl2+. They also show focal positivity for CD117 (cKit) and patchy positivity for TdT. The blast cells were negative for all other relevant markers including CD10, CD20, CD4, myeloperoxidase, CD68, CD30 and all other T-cell markers. Comment: the positivity for CD117 is unusual but has been reported in a small number of cases of B- and T-cell ALL [23]. Our conclusion is that this is a case of B-ALL with a primitive or early phenotype.

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H&E

CD10

B-cell Lymphoblastic Leukaemia/Lymphoma

CD79a

TdT

Bone marrow

Fig 4.4 B-lymphoblastic lymphoma in the testis usually occurs as a relapse of ALL or lymphoblastic lymphoma in treated children so the diagnosis is expected. It may occur from anew in elderly people in whom it can be confused with other lymphomas, or indeed germ-cell tumours if an appropriate immunophenotype is not performed.

extramedullary involvement (also known as granulocytic sarcomas). Myeloblastic proliferations are positive for myeloperoxidase, CD43, CD68, elastase and lysozyme. In general, these tumours are negative for B- and T-cell antigens such as CD20 and CD3, although, as mentioned above, increasing numbers of primitive leukaemias are being reported to show so-called aberrant or overlapping phenotypes. Absence of TdT and CD34 is helpful, although about a third of myeloblastic tumours express these antigens [20]. Promyelocytic leukaemia has been reported to be positive for the CD79a B-cell-associated antigen [21]. This is not in fact CD79a but a cross-reaction with the antibody HM57 and does not occur with the most widely used anti-CD79a antibody JCB 117 [22].

Round cell tumours Particularly in children these may be responsible for diagnostic difficulties (Fig 4.3). The expression of the leukocyte common antigen CD45, together with other B-cell markers, may be of critical value in this context. The important rule for diagnosis is not to guess but to try to make a positive diagnosis by using a full range of antibodies against epithelial, neural, muscle and other non-lymphoid antigens.

Prognosis and treatment Lymphoblastic lymphoma/leukaemia is an aggressive disease but responds well to intensive chemotherapy. The current

long-term survival rate in children is over 70% although, for reasons that are unclear, this is much lower in adults. Possible explanations include more unfavourable cytogenetics as well as a lower tolerance to and increased side effects from aggressive chemotherapy in adults. Relapse frequently occurs in so-called ‘sanctuary’ sites such as the brain and testis (Fig 4.4). Treatment is continually being refined to improve survival rates while minimising the side effects of chemotherapy – especially the long-term ones such as second malignancies. The role of bone marrow transplantation remains unclear and is generally used only for recurrent or resistant disease.

References 1. Murphy SB. Childhood non-Hodgkin’s lymphoma. N Engl J Med 1978;299:1446–8. 2. Coleman CN, Picozzi VJ Jr, Cox RS, et al. Treatment of lymphoblastic lymphoma in adults. J Clin Oncol 1986;4:1628–37. 3. Hanson CA, Ross CW, Schnitzer B. Anti-CD34 immunoperoxidase staining in paraffin sections of acute leukemia: comparison with flow cytometric immunophenotyping. Hum Pathol 1992; 23:26–32. 4. Cohen PL, Hoyer JD, Kurtin PJ, Dewald GW, Hanson CA. Acute myeloid leukemia with minimal differentiation. A multiple parameter study [see comments]. Am J Clin Pathol 1998;109:32–8.

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5. Hanson CA, Abaza M, Sheldon S, Ross CW, Schnitzer B, Stoolman LM. Acute biphenotypic leukaemia: immunophenotypic and cytogenetic analysis. Br J Haematol 1993;84:49–60. 6. Arico M, Valsecchi MG, Camitta B, et al. Outcome of treatment in children with Philadelphia chromosome-positive acute lymphoblastic leukemia. N Engl J Med 2000;342:998–1006 7. Moorman AV, Harrison CJ, Buck GA, et al. Karyotype is an independent prognostic factor in adult acute lymphoblastic leukemia (ALL): analysis of cytogenetic data from patients treated on the Medical Research Council (MRC) UKALLXII/ Eastern Cooperative Oncology Group (ECOG) 2993 trial. Blood 2007;109:3189–97. 8. Bungaro S, Dell’Orto MC, Zangrando A, et al. Integration of genomic and gene expression data of childhood ALL without known aberrations identifies subgroups with specific genetic hallmarks. Genes Chromosomes Cancer 2009;48:22–38. 9. Den Boer ML, van Slegtenhorst M, De Menezes RX, et al. A subtype of childhood acute lymphoblastic leukaemia with poor treatment outcome: a genome-wide classification study. Lancet Oncol 2009;10:125–34 10. Tawa A, Hozumi N, Minden M, Mak TW, Gelfand EW. Rearrangement of the T-cell receptor beta-chain gene in nonT-cell, non-B-cell acute lymphoblastic leukemia of childhood. N Engl J Med 1985;313:1033–7. 11. van der Velden VH, Bruggemann M, Hoogeveen PG, et al. TCRB gene rearrangements in childhood and adult precursor-B-ALL: frequency, applicability as MRD-PCR target, and stability between diagnosis and relapse. Leukemia 2004;18:1971–80. 12. Pilozzi E, Pulford K, Jones M, et al. Co-expression of CD79a (JCB117) and CD3 by lymphoblastic lymphoma. J Pathol 1998;186:140–3. 13. Hashimoto M, Yamashita Y, Mori N. Immunohistochemical detection of CD79a expression in precursor T cell lymphoblastic lymphoma/leukaemias. J Pathol 2002;197:341–7.

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14. Pilozzi E, Muller-Hermelink HK, Falini B, et al. Gene rearrangements in T-cell lymphoblastic lymphoma. J Pathol 1999;188: 267–70. 15. Soslow RA, Zukerberg LR, Harris NL, Warnke RA. BCL-1 (PRAD-1/cyclin D-1) overexpression distinguishes the blastoid variant of mantle cell lymphoma from B-lineage lymphoblastic lymphoma. Mod Pathol 1997;10:810–17. 16. Petrella T, Dalac S, Maynadié M, et al. CD4+ CD56+ cutaneous neoplasms: A distinct hematological entity? Am J Surg Pathol 1999;23:137–46. 17. Chaperot L, Bendriss N, Manches O, et al. Identification of a leukemic counterpart of the plasmacytoid dendritic cells. Blood 2001;97:3210–17. 18. Petrella T, Comeau MR, Maynadie M, et al. ‘Agranular CD4+ CD56+ hematodermic neoplasm’ (blastic NK-cell lymphoma) originates from a population of CD56+ precursor cells related to plasmacytoid monocytes. Am J Surg Pathol 2002;26:852–62. 19. Marafioti T, Paterson JC, Ballabio E, et al. Novel markers of normal and neoplastic human plasmacytoid dendritic cells. Blood 2008;111:3778–92. 20. Orazi A, Cotton J, Cattoretti G, et al. Terminal deoxynucleotidyl transferase staining in acute leukemia and normal bone marrow in routinely processed paraffin sections. Am J Clin Pathol 1994;102:640–5. 21. Arber DA, Jenkins KA, Slovak ML. CD79 alpha expression in acute myeloid leukemia. High frequency of expression in acute promyelocytic leukemia. Am J Pathol 1996;149:1105–10. 22. Mason DY, Cordell JL, Brown MH, et al. Cd79a – a novel marker for B-cell neoplasms in routinely processed tissue samples. Blood 1995;86:1453–9. 23. Uckan D, Hicsonmez G, Yetgin S, et al. CD34/CD117 coexpression in childhood acute leukemia. Leuk Res 2000;24: 201–6.

5

T-cell Lymphoblastic Lymphoma/Leukaemia

The morphology of this blastic lesion is identical to that of B-cell lymphoblastic lymphoma/leukaemia. It is said to represent about 80% of lymphoblastic lymphomas but this is often confused by trying to eliminate the predominantly B-cell leukaemic cases from the comparison [1]. If lymphoblastic lymphoma/leukaemia is considered as one entity then T-cell cases are much less common. Indeed it took the combined efforts of 9 specialist haematopathology units to provide 150 cases of T-lymphoblastic neoplasia for a study of its phenotype [2]. In our Oxford database, only 9 of 246 cases of lymphoblastic lymphoma/leukaemia are T cell in phenotype.

Clinical features Apart from the bone marrow the mediastinum is the most commonly involved organ. Its rapid growth may give rise to tracheal or superior venal caval compression, necessitating urgent admission to hospital. There is infiltration of bone marrow in virtually all cases. Whether or not these should be considered as leukaemic is arbitrary. Certainly, unlike B-cell cases, a frankly leukaemic picture in the peripheral blood is uncommon (less than 15% of cases). This is what accounts for many sources stating that T-cell lymphoblastic lymphoma is more common than B cell.

Immunophenotype All cases are CD3+ usually homogeneously, but a small number will demonstrate only focal staining on about half of the tumour cells. They are all positive for terminal deoxynucleotidyl transferase (TdT) and most cases will also express CD1a, CD2, CD5, CD7 and CD43 (Fig 5.2). Staining for CD4 and CD8 is variable but in a significant proportion of cases both antigens are coexpressed. Positivity for CD10, CD34 and/or CD99 is seen in a proportion of cases. Perhaps surprising is the observation that 40–50% of T-lymphoblastic lesions coexpress to some extent the B-cell marker CD79a, and in a quarter of these the expression is as complete as the T-cell staining (Fig 5.3) [2,3]. No other B-cell marker has been noted on these cases and all showed T-cell receptor (TCR) gene rearrangement but germline Ig genes [4]. The meaning of this staining pattern is not known but, as coexpression is not seen in B-cell cases, it is important for haematopathologists to be aware of this so as not to confuse these lesions. Some cases also express natural killer (NK) cell antigens (CD56 and -57) and, although these are usually easily separated from the extranodal NK/T lymphomas on clinical and morphological grounds, they can be very difficult to differentiate from aggressive NK cell leukaemias. CD117 (cKIT) is present in a small number of T-lymphoblastic lymphomas and has been associated with activating mutations of FLT3 [5].

Histology Cytogenetics Occasional cases of T-cell lymphoblastic lymphoma have markedly convoluted blastic nuclei but overall the cytology and architectural pattern is identical to that seen in B-cell cases (Fig 5.1). In some cases macrophages with tingible bodies may give a ‘starry-sky’ appearance.

About a third of cases have abnormalities, either translocations or deletions, in a variety of genes most commonly involving the various TCR loci on chromosomes 7 or 14 with genes such as HOX11 (chromosome 10), HOX11L2

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Case 1

Case 2

Case 3

Case 4

Case 5

Fig 5.1 The histology of five different cases of T-cell lymphoblastic lymphoma shows that there is considerable cytological heterogeneity in this entity which results partially from different fixation and staining protocols.

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CD3

CD1a

CD8

CD43

CD10

Proliferation

TdT Fig 5.2 The points to pick out here are that only a proportion of cases will be CD8+ and some will also express CD4. The proliferation index is high but not more than 90% (and usually lower) and nuclear staining is required before counting TdT staining as positive.

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CD79a expression in T-lymphoblastic lymphoma

CD3

Case 1:

Case 2:

CD79a

CD3

CD79a

(chromosome 5), MYC (chromosome 8) and TAL1 (chromosome 1). TAL1 encodes a transcription factor with a basic helix–loop–helix pattern that is involved in growth control of mammalian haematopoietic cells. Of interest is the fact that immunocytochemical studies show expression of TAL-1 protein in approximately 50% of T-lymphoblastic lesions, indicating that abnormalities of TAL-1 regulation occurring later than genetic translation are also associated with blastic T-cell neoplasia [6,7]. Deletions also occur, especially del(9p), involving loss of the tumour suppressor CDKN2A, as do activating mutations of the important T-cell development gene NOTCH1.

72

Fig 5.3 Two cases (1 and 4) that coexpress the B-cell antigen CD79a compared with a T-cell case (2) and a B-cell case (3) that do not coexpress.

Differential diagnosis The differential diagnosis on morphological grounds is the same as that previously discussed for B-lymphoblastic lymphomas (see Chapter 4 for details). Careful immunohistochemical study is usually the key to distinguishing T-lymphoblastic lymphoma from other lesions such as B-lymphoblastic lymphoma, the blastoid variant of mantle cell lymphoma, Burkitt and Burkitt-like lymphoma, myeloblastic proliferations, blastic plasmacytoid dendritic cell tumour and round cell tumours, especially in children.

CHAPTER 5

T-cell Lymphoblastic Lymphoma/Leukaemia

CD3

CD79a

Case 3: Another B&T antigen co-expressing lymphoblastic lymphoma

Fig 5.3 (continued)

Case 4: Typical B-cell lymphoblastic lymphoma

Although they do not consist of blastic cells some lymphocyte-rich thymomas may be responsible for diagnostic difficulties, especially on needle biopsy specimens. Indeed, the lymphoid cells in these tumours have the same set of antigens as seen in lymphoblastic lymphoma (i.e. CD1a, CD2, CD3, CD43) and, in addition, are strongly positive for TdT. Of diagnostic value is the demonstration of the meshwork of epithelial cells in thymoma with antibodies against epithelial membrane antigen (EMA) and cytokeratins (Fig 5.4). In difficult cases, the clinical presentation may be crucial because most patients with thymoma do not present with the rapidly progressive disease seen in lymphoblastic lymphoma.

Prognosis and treatment The prognosis and treatment are not known to be different from B-cell lymphoblastic lymphoma/leukaemias in agematched groups of patients. As patients present at later ages, they tend to have more tissue disease and a poorer prognosis. Treatment is with multidrug chemotherapy aimed at producing long remissions. Central nervous system prophylaxis is part of most protocols. Radiotherapy used to be a first-line therapy for mediastinal disease but its efficacy is now being questioned, although it remains extremely valuable for emergency presentations.

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HE high power CD4

HE low power

CD79a

Cytokeratin

CD117 (cKit)

CD3

CD8

TdT

CD10

Fig 5.4 This is an example of a mediastinal needle biopsy in a young adult showing a blastic lymphoid infiltration that is cytokeratin negative (note the small thymic remnant present in the CK stain (top left), which is CD3+ CD4− CD8− (top row), and CD79a+ CD117+ TdT focally+ CD10− (bottom row).

References 1. Warnke R, Weiss L, Chan J, Cleary M, Dorfman R. Tumors of the Lymph Nodes and Spleen. Washington: Armed Forces institute of Pathology, 1995. 2. Pilozzi E, Pulford K, Jones M, et al. Co-expression of CD79a (JCB117) and CD3 by lymphoblastic lymphoma. J Pathol 1998; 186:140–3. 3. Hashimoto M, Yamashita Y, Mori N. Immunohistochemical detection of CD79a expression in precursor T cell lymphoblastic lymphoma/leukaemias. J Pathol 2002;197:341–7. 4. Pilozzi E, Muller-Hermelink HK, Falini B, et al. Gene

74

rearrangements in T-cell lymphoblastic lymphoma. J Pathol 1999;188:267–70. 5. Paietta E, Ferrando AA, Neuberg D, et al. Activating FLT3 mutations in CD117/KIT(+) T-cell acute lymphoblastic leukemias. Blood 2004;104:558–60. 6. Chetty R, Pulford K, Jones M, et al. SCL/Tal-1 expression in T-acute lymphoblastic leukemia: an immunohistochemical and genotypic study. Hum Pathol 1995;26:994–8. 7. Chetty R, Pulford K, Jones M, et al. An immunohistochemical study of TAL-1 protein expression in leukaemias and lymphomas with a novel monoclonal antibody, 2TL 242. J Pathol 1996;178: 311–15.

6

B-cell Chronic Lymphocytic Leukaemia

This lymphoma is indistinguishable cytologically from the leukaemia of the same name. It is composed of small round lymphocytes variably admixed with larger cells known as prolymphocytes and paraimmunoblasts. The World Health Organization (WHO) recommends calling cases without peripheral blood involvement ‘small lymphocytic lymphoma’.

Clinical features Chronic lymphocytic leukaemia (CLL; also known as small lymphocytic lymphoma) is a disease of elderly people usually occurring after the age of 60 and is extremely rare in patients younger than 40 years. Its incidence depends on whether the frank leukaemias are included (15–20% of all NHLs) or excluded (<5% of all non-Hodgkin lymphomas or NHLs). There is no point engaging in a sterile argument with clinicians over the terminology of this disease, which is why the alternative name of ‘small lymphocytic lymphoma’ is available. The clinical course of CLL, whether or not it presents with leukaemia, is slowly progressive with all or virtually all cases developing blood and bone marrow involvement with time. Widespread tissue dissemination usually develops, although an alternative terminal course may occur from transformation to an aggressive large-cell lymphoma (Richter syndrome) [1].

Some cases show a marked plasmacytoid differentiation and were separately classified as lymphoplasmacytoid lymphoma in the Kiel classification. It is now generally agreed that these should be considered as CLL. Less than 10% of CLL cases usually transform into an aggressive diffuse largecell lymphoma (Richter transformation) that occasionally has an almost anaplastic morphology (Fig 6.2). Occasional cases have been reported to transform into Hodgkin lymphoma usually with Epstein–Barr virus (EBV)positive Reed–Sternberg cells (Fig 6.3) [2,3]. In the spleen, involvement is initially of the white pulp with later diffuse extension into the red pulp. Bone marrow infiltration commences with interstitial infiltration or central lymphoid nodules but may develop a number of different patterns (diffuse, paratrabecular and central) with progression. These extranodal manifestations are often difficult to distinguish from other low-grade B-cell neoplasms without clinical correlation or immunophenotyping.

Blood involvement Those cases not presenting with a leukaemic picture usually develop one with time. The definition of leukaemia in this entity is arbitrary but a lymphocytosis of more than 5 × 109/L is usually present. A number of healthy individuals have relatively small monoclonal B-cell lymphocytoses (always <5 × 109/L) with the characteristic phenotype of CLL [4]. These are of interest as potential precursors of CLL although as yet there is no evidence to substantiate this.

Histology Immunophenotype In lymph nodes CLL normally occurs as a diffuse infiltration. There is usually some vague nodularity caused by an accumulation of larger cells (prolymphocytes and paraimmunoblasts) in so-called ‘proliferation centres’ (Fig 6.1).

CLL cells express the B-cell markers CD20 (sometimes weakly) and CD79a but are negative for CDw76(DBA44) (Table 6.1 and Fig 6.4).

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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In contrast to normal B lymphocytes, almost all cases coexpress CD43 and CD5 antigens (Fig 6.5). CD5 is usually more weakly expressed on CLL cells than on surrounding reactive T cells, and occasionally requires a careful search of the paraffin sections, sometimes requiring frozen sections

H&E low power

H&E high power

Proliferation centres

H&E high power

for certainty. CD23 is usually positive and useful for differentiating small lymphocytic lymphoma from mantle cell lymphoma (Table 6.1). In some examples the labelling for CD23 may be quite weak whereas in others only the prolymphocytes and paraimmunoblasts label. Cyclin D1 is negative, although occasional positive cells may be seen especially in proliferation centres [5]. This is becoming an increasing problem in immunodiagnosis as anti-cyclin D1 antibodies become more avid and staining machines more sensitive, but is not surprising because cyclin D1 is a protein active to a certain extent in virtually all metabolising cells. CD21 is also, perhaps surprisingly, frequently positive on CLL cells, although any underlying follicular dendritic cells in overrun follicles are usually easily identified by their more intense staining and characteristic morphology [6]. Surface immunoglobulins are only reliably demonstrated in frozen sections but in some cases with careful attention to technique κ and λ light chain restriction can be identified (Fig 6.6). The proliferation index (Ki67) is usually very low (<5%) in these tumours.

Genetics

Proliferation centres at high power Fig 6.1 A selection of low- and high-power views illustrating the architectural and cytological features of chronic lymphocytic leukaemia (CLL) including the characteristic feature of proliferation centres. This is often more dramatically seen in Giemsa sections (middle left and bottom left) though a high-power haematoxylin and eosin (H&E) is shown for comparison (bottom right).

The underlying immunoglobulin gene rearrangements in CLL are divided almost equally into cases with somatic mutations and those that are not mutated. Studies have shown that the mutated cases have a better prognosis than those that are not. Immunostaining for ZAP-70 and CD38 provides an approximate surrogate to recognise cases that have not mutated [7]. Deletions on chromosome 13q and trisomy 12 are relatively common, as are deletions and mutations affecting p53 on chromosome 17. The latter enables p53 immunostaining to be used as a marker of poor prognosis [8].

CLL variant

Lymphoplasmacytoid

Richter transformation

Large cell

Anaplastic

Fig 6.2 Examples of variant morphologies in chronic lymphocytic leukaemia (CLL) are the lymphoplasmacytoid variant and the Richter transformation to a high-grade large cell or anaplastic morphology.

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HE

B-cell Chronic Lymphocytic Leukaemia

CD3

CD30

CD5

EBV LMP1

Fig 6.3 Hodgkin lymphoma-like transformation of chronic lymphocytic leukaemia (CLL) showing the Reed–Sternberg cells (top left) which are CD30+ (bottom left) and EBV+ (bottom right). The surrounding lymphocytes are identified as CLL cells by their negativity for CD3 but positivity for CD5 (top right panel).

Table 6.1 The typical immunophenotype of chronic lymphocytic leukaemia compared with its main differential diagnoses IgM

IgD

CD5

CD10

CD23

CD43

bcl-6

Cyclin D1

Chronic lymphocytic leukaemia

(+)

(+)

+

-

+

+

−

−

Lymphoplasmacytic lymphoma Mantle cell lymphoma Follicular lymphoma Marginal zone lymphoma Splenic marginal zone lymphoma

+ + + + +

− ± ± − +

− + − − −

− − ± − −

± − ± ± −

± + ± −

− − + − −

− + − − −

B-cell prolymphocytic lymphoma In the REAL classification it was suggested that this rare entity was part of the clinical spectrum of CLL. Further discussion has brought agreement that true prolymphocytic leukaemia is distinctly different. Patients present with

splenomegaly and high white blood cell counts, with more than half of these being prolymphocytes (Fig 6.7). These patients have no previous history of CLL and the tumour cells are usually CD5− and CD23−. B-cell prolymphocytic lymphoma (PLL) is difficult to treat and generally has a poor prognosis [9,10].

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CD79a

λ

CD20

Fig 6.6 Demonstration of light chain restriction on most cases of chronic lymphocytic leukaemia (CLL) is not easy on paraffin sections and may need frozen sections if considered important for diagnosis.

Fig 6.4 Chronic lymphocytic leukaemia (CLL) expresses most B-cell markers such as CD79a or CD20 but sometimes surprisingly weakly compared with other B-cell lymphomas.

CD5

Cyclin D1

κ

CD43

CD23

CD21

Fig 6.5 The most useful current markers for chronic lymphocytic leukaemia (CLL) are CD5, CD43 and CD23 (which may be quite weak on paraffin sections and need careful inspection to appreciate). CD21 (frequently positive in CLL) shows only scattered dendritic reticulum cells in this case and cyclin D1 is negative (note that many endothelial cells are cyclin D1 positive and provide a useful internal control).

Differential diagnosis Mantle cell lymphoma The most frequent and important differential diagnosis is with mantle cell lymphoma. Positivity for CD23 but not cyclin D1 provides the two most helpful immunostains (Fig

78

6.8). Previous reports of small numbers of cases of mainly PLL being cyclin D1 positive and to possess the translocation t(11:14) are now considered to be leukaemic variants of mantle cell lymphoma [11,12]. The positivity for CD5 and CD23 is useful in differentiating it from other low-grade B-cell neoplasms, although these two markers can be troublesome to detect in paraffin sec-

CHAPTER 6

Fig 6.7 Prolymphocytic leukaemia is a clinicopathological correlation as much as a straightforward histological diagnosis. In the tissues, typically the spleen, the predominant cell is a little larger than a small lymphocyte with a single prominent nucleolus rather than the mottled chromatin of a lymphocyte. But one should remember that prolymphocytes can be abundant in otherwise unremarkable chronic lymphocytic leukaemia.

H&E

Giemsa

H&E low power

Frozen

CD5

Paraffin

B-cell Chronic Lymphocytic Leukaemia

H&E high power

Frozen

CD23

Paraffin

CD20

Fig 6.8 Distinguishing chronic lymphocytic leukaemia (CLL) from mantle cell lymphoma may be difficult on cytological and/or, as in this case, architectural grounds where there is a ‘mantle zone’ pattern. A good immunophenotype showing CD5 and CD23 positivity with cyclin D1 negativity (not shown here) will provide a clear diagnosis.

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tions and require careful attention to antigen retrieval and sensitive immunohistochemistry techniques. The demonstration of follicular dendritic cell networks (using CNA.42, CD21 or CD35 antibodies) is also helpful for differentiating CLL from mantle cell lymphoma, which usually shows hyperplastic follicular dendritic cell meshworks.

Follicular lymphoma Occasionally the nodularity caused by the proliferation centres in CLL may lead to confusion with follicular lymphoma. Usually the cytology of follicular lymphoma with its predominance of centrocytes allows a confident distinction. This can now be confirmed immunocytochemically by immunostaining for CD5, CD10 and bcl-6 protein (see Table 6.1) [13–15].

Prognosis and treatment The clinical course is usually described as indolent, although the 10-year survival is lower than for most other low-grade lymphomas. This may reflect the age of patients at presentation more than the biology of the lymphoma. Therapy is currently only palliative, although recent results using the therapeutic antibody CAMPATH-1 are encouraging [16]. In a recent report [17], histological characteristics of lymph nodes were correlated with prognosis. The size of proliferation centres and their proliferation activity (Ki-67 index) were important predictors of survival. Patients with “accelerated” CLL (defined as expanded and confluent proliferation centers broader than a 20x field) had a shorter survival than those with small or absent proliferation centers (“non-accelerated” CLL). A Ki-67 index greater than 40% per proliferation centres, had also a poorer outcome. Overall, median survival of patients with “non-accelerated” CLL was 76 months compared to 34 months for those with “accelerated’’ CLL. In that study, median survival of patients with CLL with transformation to diffuse large B-cell lymphoma was 4.3 months.

References 1. Ben-Ezra J, Burke J, Swartz W, et al. Small lymphocytic lymphoma: a clinicopathologic analysis of 268 cases. Blood 1989; 73:579–87. 2. Brecher M, Banks PM. Hodgkin’s disease variant of Richter’s syndrome. Report of eight cases. Am J Clin Pathol 1990;93: 333–9.

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3. Fayad L, Robertson LE, O’Brien S, et al. Hodgkin’s disease variant of Richter’s syndrome: experience at a single institution. Leuk Lymphoma 1996;23:333–7. 4. Rawstron AC, Green MJ, Kuzmicki A, et al. Monoclonal B lymphocytes with the characteristics of ‘indolent’ chronic lymphocytic leukemia are present in 3.5% of adults with normal blood counts. Blood 2002;100:635–9. 5. O’Malley DP, Vance GH, Orazi A. Chronic lymphocytic leukemia/ small lymphocytic lymphoma with trisomy 12 and focal cyclin d1 expression: a potential diagnostic pitfall. Arch Pathol Lab Med 2005;129:92–5. 6. Echeverri C, Fisher S, King D, Craig FE. Immunophenotypic variability of B-cell non-Hodgkin lymphoma: a retrospective study of cases analyzed by flow cytometry. Am J Clin Pathol 2002;117:615–20. 7. Morilla A, Gonzalez de Castro D, Del Giudice I, et al. Combinations of ZAP-70, CD38 and IGHV mutational status as predictors of time to first treatment in CLL. Leuk Lymphoma 2008;49:2108–15. 8. Schlette EJ, Admirand J, Wierda W, et al. p53 expression by immunohistochemistry is an important determinant of survival in patients with chronic lymphocytic leukemia receiving frontline chemo-immunotherapy. Leuk Lymphoma 2009;50: 1597–605. 9. Galton D, Goldman J, Wiltshaw E, Catovsky D. Prolymphocytic leukaemia. Br J Haematol 1974;27:7–23. 10. Melo J, Catovsky D, Galton D. The relationship between chronic lymphocytic leukaemia and prolymphocytic leukaemia. I. Clinical and laboratory features of 300 patients and characterization of an intermediate group. Br J Haematol 1986;63: 377–87. 11. Kobayashi H, Kitano K, Saito H, et al. Overexpression of the PRAD1 oncogene in a patient with prolymphocytic leukemia with t(11;14)(q13;q32). Cancer Genet Cytogenet 1995;84:69–72. 12. Ruchlemer R, Parry-Jones N, Brito-Babapulle V, et al. B-prolymphocytic leukaemia with t(11;14) revisited: a splenomegalic form of mantle cell lymphoma evolving with leukaemia. Br J Haematol 2004;125:330–6. 13. Dogan A, Bagdi E, Munson P, Isaacson PG. CD10 and BCL-6 expression in paraffin sections of normal lymphoid tissue and B-cell lymphomas. Am J Surg Pathol 2000;24:846–52. 14. Raible MD, Hsi ED, Alkan S. Bcl-6 protein expression by follicle center lymphomas. A marker for differentiating follicle center lymphomas from other low-grade lymphoproliferative disorders. Am J Clin Pathol 1999;112:101–7. 15. Falini B, Fizzotti M, Pileri S, Liso A, Pasqualucci L, Flenghi L. Bcl-6 protein expression in normal and neoplastic lymphoid tissues. Ann Oncol 1997;8(suppl 2):101–4. 16. Keating MJ. Chronic lymphocytic leukemia. Semin Oncol 1999;26(5 suppl 14):107–14. 17. Giné E, et al. Expanded and highly active proliferation centers identify a histological subtype of chronic lymphocytic leukemia (“accelerated” chronic lymphocytic leukemia) with aggressive clinical behavior. Hematologica 2010;95:1526–33.

7

Splenic B-cell Marginal Zone Lymphoma

Splenic B-cell marginal zone lymphoma (splenic lymphoma) has often been confused with other low-grade B-cell conditions including chronic lymphocytic leukaemia (CLL), immunocytoma and hairy cell leukaemia. It was only identified as a lymphoma in its own right in 1992 [1].

Blood involvement A frank lymphocytosis with characteristic villous lymphocytes occurs only in a minority of patients, at least at presentation.

Clinical features Patients are usually older adults who present with splenomegaly or associated conditions such as hypersplenism and autoimmune haemolytic anaemias or thrombocytopenias.

Histology There is a characteristic biphasic replacement of splenic white pulp (Fig 7.1). This consists of a central dark zone of small lymphocytes surrounded by a lighter area of medium-sized marginal zone-like cells with pale cytoplasm, and interspersed blast cells. It is this lighter zone that gives rise to the name splenic marginal zone lymphoma (SMZL) and that extends out to infiltrate the red pulp as well. There is now considerable doubt that this is a marginal zone lymphoma, one argument against this being the biphasic pattern of the lymphoma whereas true marginal zone lymphomas are more homogeneous. Further evidence against it comes from immunocytochemical studies [2–4]. Plasmacytic differentiation may be observed. Splenic hilar lymph nodes may be involved by a nodular infiltration of lymphocytes with admixed blasts. There is no marginal zone pattern as seen in nodal involvement by MALT (mucosaassociated lymphoid tissue) lymphomas. Other lymph nodes are rarely involved, although bone marrow is usually infiltrated both by lymphocytic nodules in the centre of the marrow spaces and by a more diffuse intrasinusoidal spread.

Immunophenotype Splenic lymphoma cells are of B phenotype (CD20+, CD79a+) (Table 7.1 and see Fig 7.1). A significant proportion of these tumours are positive for CDw76/DBA-44 antibody, but it is the pattern of immunostaining with anti-immunoglobulins that is distinctive in this condition. Splenic lymphoma occupies both the mantle and the marginal zones as shown by the absence of a residual IgDpositive mantle zone. Other low-grade B-cell lymphomas in the spleen typically either replace the white pulp or are restricted to one zone, usually the marginal zone. A combination of immunoglobulin and bcl-2 protein staining usually enables one to sort these out (Fig 7.2). Then a detailed immunophenotype will enable the lymphoma to be subtyped [4]. In particular splenic lymphoma cells are negative for CD5, CD10, CD43, cyclin D1, annexin A1 and also usually for CD23. Staining for Ki67 shows a characteristic jumbled or targetoid appearance with relatively brisk proliferative activity in both the marginal zone and overrun germinal centres.

Cytogenetics The only consistent cytogenetic abnormality reported is loss of chromosome 7q31-32 in up to 40% of cases (this is rare in other low-grade B-cell lymphomas) [5].

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Splenic B-cell Marginal Zone Lymphoma

CD79a

bcl-2

CD3

CD43

Mantle zone

Fig 7.1 The histology and immunophenotype of splenic lymphoma showing the expansion of the splenic marginal zones with a polymorphic collection of lymphocytes of varying cytologies around preserved germinal centres (bcl2−). The lymphoma cells are variably bcl-2+ B cells which are CD43−.

Table 7.1 Comparing the immunophenotypes of splenic marginal zone lymphoma with its main differential diagnoses

Splenic marginal zone lymphoma Marginal zone lymphoma Follicular lymphoma Mantle cell lymphoma Lymphoplasmacytic lymphoma Chronic lymphocytic leukaemia

82

IgM

IgD

CD5

CD10

CD23

CD43

bcl-6

Cyclin D1

+ + + + + (+)

+ − ± ± − (+)

− − − + − +

− − + − − −

± ± ± − ± +

− ± − + ± +

− − + − − −

− − − + − −

CHAPTER 7

Splenic B-cell Marginal Zone Lymphoma

HE

HE

HE

CD20

CD79a

CD10

CD21

bcl2

κ

IgM

IgD

λ

mib1

Fig 7.2 In this case the splenic marginal zone lymphoma has overrun the germinal centres. The tumour cells are CD20+ and CD79a+ but CD10−. The tumour cells in the marginal zone area are bcl2+ but lose this as they colonise the previous germinal centres, the framework of which is outlined by CD21. The tumour cells are positive for both IgM and IgD, show κ light chain restriction and have a broken up but relatively high proliferative index with Ki67.

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Splenic B-cell Marginal Zone Lymphoma

HE

HE

CD20

CD10

CD23

CD23

bcl2

CD3

CD5

Fig 7.3 Example of a typical splenic marginal zone lymphoma with unusual positivity for CD23.

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Differential diagnosis In the spleen the differential diagnosis is generally with the other ‘low-grade’ B-cell lymphomas (Fig 7.3). Attention to imunophenotyping, as described above, allied with a careful clinicopathological correlation is the best way to make a confident diagnosis. Cyclin D1 immunostaining is the crucial marker in distinguishing it from mantle cell lymphoma. Early reports of t(11;14) and cyclin D1 positivity in splenic lymphoma are now generally believed to be mistaken mantle cell lymphomas as more detailed studies show splenic lymphomas to be cyclin D1 negative [6]. A note of caution has been raised by a study of six cases of splenic lymphoma with increased numbers of blasts and an aggressive clinical picture, of which two expressed cyclin D1, although again these may be unusual examples of mantle cell lymphoma [7]. Although the distinction from hairy cell leukaemia is rarely problematic any doubts may be dispelled by showing negativity for annexin A1 [8].

Splenic diffuse red pulp small B-cell lymphoma This is a very rare B-cell lymphoma in which there is red pulp sinusoidal infiltration of the spleen by unremarkable, small, basophilic, lymphoid cells with little or no evidence of residual white pulp. A similar intrasinusoidal infiltration pattern is seen in the bone marrow. The immunophenotype is virtually identical to SMZL apart from usually being IgD negative; hence an alternative name for it has been SMZL diffuse variant [9].

Prognosis and treatment Survival studies available to date suggest that this condition has an excellent prognosis and that the treatment of choice is splenectomy alone without any chemotherapy. Some

Splenic B-cell Marginal Zone Lymphoma

cases of transformation into large cell lymphoma have been reported [10].

References 1. Schmid C, Kirkham N, Diss T, Isaacson P. Splenic marginal zone cell lymphoma. Am J Surg Pathol 1992;16:455–66. 2. Mollejo M, Menarguez J, Lloret E, et al. Splenic marginal zone lymphoma: a distinctive type of low-grade B-cell lymphoma. A clinicopathological study of 13 cases. Am J Surg Pathol 1995; 19:1146–57. 3. Mollejo M, Lloret E, Menarguez J, Piris MA, Isaacson PG. Lymph node involvement by splenic marginal zone lymphoma: morphological and immunohistochemical features. Am J Surg Pathol 1997;21:772–80. 4. Piris MA, Mollejo M, Campo E, Menarguez J, Flores T, Isaacson PG. A marginal zone pattern may be found in different varieties of non- Hodgkin’s lymphoma: the morphology and immunohistology of splenic involvement by B-cell lymphomas simulating splenic marginal zone lymphoma. Histopathology 1998;33: 230–9. 5. Mateo M, Mollejo M, Villuendas R, et al. 7q31-32 allelic loss is a frequent finding in splenic marginal zone lymphoma. Am J Pathol. 1999;154:1583–9. 6. Savilo E, Campo E, Mollejo M, et al. Absence of cyclin D1 protein expression in splenic marginal zone lymphoma. Mod Pathol 1998;11:601–6. 7. Lloret E, Mollejo M, Mateo MS, et al. Splenic marginal zone lymphoma with increased number of blasts: an aggressive variant? Hum Pathol 1999;30:1153–60. 8. Falini B, Tiacci E, Liso A, et al. Simple diagnostic assay for hairy cell leukaemia by immunocytochemical detection of annexin A1 (ANXA1). Lancet 2004;363:1869–70. 9. Traverse-Glehen A, Baseggio L, Bauchu EC, et al. Splenic red pulp lymphoma with numerous basophilic villous lymphocytes: a distinct clinicopathologic and molecular entity? Blood 2008;111:2253–60. 10. Kuwayama M, Machii T, Yamaguchi M, Yamaguti K, Kitani T, Kanakura Y. Blastic transformation of splenic lymphoma with villous lymphocytes after a well-controlled chronic phase of more than 10 years. Int J Hematol 2000;71:167–71.

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Hairy Cell Leukaemia

Hairy cell leukaemia (HCL) is characterised by circulating mononuclear cells with fine villous projections (‘hairy cells’) and splenomegaly without lymphadenopathy.

Blood involvement

Clinical features

Peripheral blood is usually involved although it is rare to find more than a few scattered hairy cells in the typical smear. Frank leukaemias are rare. Pancytopenia associated with monocytopenia is a common finding.

Patients are elderly, predominantly male and pancytopenic. Symptoms are usually related to the splenomegaly (abdominal pain or distension) or bone marrow infiltration (bruising, fatigue, infection).

Histology The spleen is typically very large (2 kg or more) with a deep burgundy red coloration and a friable soggy feel to it. It is extensively infiltrated throughout the red pulp, with little or no sign of remaining white pulp. The soggy feel is probably due to the pseudosinus formation of blood-filled spaces lined by hairy cells. Hairy cell leukaemia consists of an infiltrate of non-cohesive homogeneous cells, looking like a halfway house between monocytes and lymphocytes. They have a bean-shaped nucleus and relatively abundant clear cytoplasm (Fig 8.1). The picture is similar in bone marrow, which is usually inaspirable regardless of the extent of the infiltration (usually ascribed to an increase in reticulin occasioned by the infiltration) (Fig 8.2). The liver is also commonly involved (portal tracts and sinusoids) though to a lesser extent than the spleen. Lymph nodes at the splenic hilum frequently show involvement, although other lymph nodes are usually unaffected even with longstanding disease. Whether hairy cell leukaemia can ever be a primary lymph node disease remains unclear, but if it does it must be exceedingly rare (Fig 8.3).

Immunophenotype The immunophenotype is characteristic and reflects the appearance of the cell as a hybrid monocyte/lymphocyte [1–3] (Fig 8.4]. Hairy cells express a mixture of histiocytic and lymphocytic antigens unlike any other lymphoma. CD10 and CD23 were initially thought to be negative but detailed studies have shown that about 20% of cases may be positive for either [4]. The most specific marker is the recently described annexin A1 because this is positive on nearly all cases of hairy cell leukaemia but not on any other B-cell lymphomas [5]. The paraffin section immunophenotype is as shown in Table 8.1.

Cytogenetics No specific abnormalities have been described although a variety of abnormalities affecting chromosomes 5 and 7 has been reported [6,7].

Differential diagnosis Hairy cell leukaemia has such a characteristic cytology, histology and immunophenotype that it is not usually confused

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Hairy Cell Leukaemia

Fig 8.1 Typical appearances of hairy cell leukaemia in the spleen shown, at low and medium power to illustrate the diffuse infiltration with red cell lakes and at high power for the characteristic morphology.

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Hairy Cell Leukaemia

Hairy cell leukaemia in the bone marrow

Cytology

CD22

CD11c

Low power histology

High power histology Fig 8.2 showing the characteristic appearance of hairy cell leukaemia in the bone marrow. CD22 is a B-cell marker and CD11c a histiocytic marker working on cytological preparations or frozen sections but not paraffin.

88

Hairy cell leukaemia in lymph node

CD79a

CD68

DBA.44

Kappa

Cyclin D1

Lambda

Fig 8.3 A case of hairy cell leukaemia presenting as a solitary lymph node without involvement of spleen or bone marrow.

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Hairy Cell Leukaemia

Hairy cell leukaemia: immunophenotype

CD79a

DBA.44

CD79a

DBA.44

DBA.44

Cyclin D1

CD20

Annexin A1

Fig 8.4 The typical immunophenotype of hairy cell leukaemia in paraffin sections. Only a proportion of cases express cyclin D1.

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Table 8.1 Immunophenotype of paraffin sections B-cell antigens ‘Hairy cell antigen’ ‘Differentiation’ antigens

Histiocytic antigens Other antigens

CD19, CD20, CD22, CD79a CDw76 (DBA.44), annexin A1 CD5 CD10, CD23 Cyclin D1 CD68 CD25, CD103, CD123

+ + − ± ± Dot + +

with any other neoplasm. Occasionally immunocytochemical results may raise the possibility of splenic lymphoma expressing CDw76 (DBA.44) or mantle cell lymphoma because of cyclin D1 expression [8,9] but putting all of the features together should eliminate any doubts. For example, in the bone marrow, splenic lymphoma shows a predominantly sinusoidal infiltration whereas hairy cell leukaemia is interstitial (both being CDw76 [DBA.44] positive). A much more common problem faces the bone marrow diagnostician where hairy cell leukaemia can be a subtle infiltrate causing severe reactive, dysplastic or even aplastic changes leading to a false diagnosis [10].

Hairy cell leukaemia variant This rare entity has been provisionally recognised in the recent World Health Organization (WHO) classification. It is a low-grade B-cell lymphoproliferation somewhere between B-cell prolymphocytic leukaemia (B-PLL) and HCL in morphology and shows a similar pattern of infiltration of bone marrow and spleen. Its immunophenotype is clearly distinct from HCL by being CD25, annexin A1− and CD123−. Pathologists are usually directed towards it by clinicians who have been alerted to it by the easily aspirable marrow and unusual cytology (and also by the resistance to traditional HCL therapy if this has been undertaken) [11].

Prognosis and treatment Hairy cell leukaemia has an indolent course and is generally easily controllable. Indeed about 10% of patients will never require any specific therapy. Patients with symptoms from bone marrow infiltration or splenomegaly may be treated with purine analogues such as 2-chlorodeoxyadenosine

Hairy Cell Leukaemia

(Cladribine) or deoxycoformycin (Pentostatin), or with interferon-α or splenectomy [12,13]. Progressive HCL, postsplenectomy, is generally responsive to therapy with a good survival rate of >85% at 5 years. Rare cases of transformation to a diffuse large B-cell lymphoma have been reported.

References 1. Hounieu H, Shashikant C, Saati T, et al. Hairy cell leukemia: diagnosis of bone marrow involvement in paraffin-embedded sections with monoclonal antibody DBA.44. Am J Clin Pathol 1992;28:26–33. 2. Hsu S, Yank K, Jaffe E. Hairy cell leukemia: a B cell neoplasm with a unique antigenic phenotype. Am J Clin Pathol 1983; 80:421–8. 3. Visser L, Shaw A, Slupsky J, Vos H, Poppema S. Monoclonal antibodies reactive with hairy cell leukemia. Blood 1989; 74:320–5. 4. Chen YH, Tallman MS, Goolsby C, Peterson L. Immunophenotypic variations in hairy cell leukemia. Am J Clin Pathol 2006; 125:251–9. 5. Falini B, Tiacci E, Liso A, et al. Simple diagnostic assay for hairy cell leukaemia by immunocytochemical detection of annexin A1 (ANXA1). Lancet 2004;363:1869–70. 6. Wu X, Ivanova G, Merup M, et al. Molecular analysis of the human chromosome 5q13.3 region in patients with hairy cell leukemia and identification of tumor suppressor gene candidates. Genomics 1999;60:161–71. 7. Cawley JC. The pathophysiology of the hairy cell. Hematol Oncol Clin North Am 2006;20:1011–21. 8. Bosch F, Jares P, Campo E, et al. PRAD-1/cyclin D1 gene overexpression in chronic lymphoproliferative disorders: a highly specific marker of mantle cell lymphoma. Blood 1994;84: 2726–32. 9. de Boer CJ, van Krieken JH, Schuuring E, Kluin PM. Bcl-1/ cyclin D1 in malignant lymphoma. Ann Oncol 1997;8(suppl 2): 109–17. 10. Brown D, Gatter K, Natkunam Y, Warnke R. Bone Marrow diagnosis: An illustrated guide. Oxford: Blackwell’s Scientific, 2006. 11. Matutes E, Wotherspoon A, Catovsky D. The variant form of hairy-cell leukaemia. Best Pract Res Clin Haematol 2003; 16:41–56. 12. Piro L, Carrera C, Carson D, Beutler E. Lasting remissions in hairy cell leukemia induced by a single infusion of 2′-chlorodeoxyadenosine. Cancer 1990;332:1117–21. 13. Spiers A, Moore D, Cassileth P, et al. Remissions in hairy-cell leukemia with pentostatin (2′-deoxycoformycin). N Engl J Med 1987;316:825–30.

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Lymphoplasmacytic Lymphoma

This lymphoma is mainly composed of lymphocytes showing plasmacytic differentiation and plasma cells. Most cases have an associated serum IgM paraprotein [1].

Clinical features Lymphoplasmacytic lymphomas (LPLs) (also previously known as immunocytomas) have a similar age distribution to chronic lymphocytic leukaemia (CLL). Most patients have an IgM serum paraprotein, with about half of these also showing the clinical features of Waldenström macroglobulinaemia (hyperviscosity, autoimmunity, cryoglobulinaemia). Some cases have a leukaemic blood picture although this is not common and should alert one to a misdiagnosis of one of the other small B-cell lymphomas [2–4].

When Dutcher bodies are readily identified they are a reliable marker for a monoclonal proliferation (Fig 9.1). Some cases are associated with a marked granulomatous reaction [5]. The sinuses are occasionally preserved and are dilated by PAS-positive lymph. In extranodal sites, LPL is becoming a rare diagnosis because most of these cases are now considered to be marginal zone derived (i.e. extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue). In the spleen, clear-cut cases have a diffuse pattern of red pulp infiltration. Cases that appear to involve the white pulp heavily are often difficult to distinguish from splenic marginal zone lymphoma.

Blood involvement A variety of red cell abnormalities associated with the macroglobulinaemia are common whereas a lymphocytosis is rare.

Histology Many, if not most, cases of LPL/immunocytoma diagnosed before the first World Health Organization (WHO) classification in sites other than bone marrow have been reassigned on review to other categories of lymphoma. This means that much of the richness of histological description in the old literature is no longer applicable. Without a clear clinical picture of Waldenström macroglobulinaemia, it is almost a diagnosis of exclusion. In lymph nodes, LPL is a diffuse infiltration of lymphoplasmacytic cells and plasma cells, often with an intrasinusoidal pattern. There is no pseudofollicle formation as seen in CLL. Periodic acid–Schiff (PAS)positive intranuclear pseudoinclusions, known as ‘Dutcher bodies’, are helpful in establishing the diagnosis but are not restricted to this category of lymphoma because they may be seen in other lymphomas when accompanied by plasmacytic differentiation, e.g. marginal zone lymphoma and follicular lymphoma.

Immunophenotype In LPL, plasma cells and occasional immunoblasts stain for cytoplasmic monotypic IgM readily detectable on paraffin sections. In addition, most of the cells are positive for CD20 and CD79a and generally negative for CD5, CD10 and CD23 (Table 9.1). A careful analysis of LPL cases with Waldenström macroglobulinaemia by flow cytometry has shown a surprisingly high albeit often weak expression of CD5, CD10 and CD23 [6]. Pathologists need to be alert to this because, as new more avid antibodies become available, coupled to sensitive staining machines, we will start to see many more of these seeming anomalies. The expression of CD43 is variable. LPL cells are usually positive for the ‘plasma cell’ markers CD38 and VS38, although negative for CD138 which generally stains only associated mature plasma cells (Fig 9.2). The proliferation index is usually low (<5%).

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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H&E low power

Lymphoplasmacytic Lymphoma

H&E Dutcher body

Cytogenetics There are no specific abnormalities recognised in LPL. Previous reports of PAX-5 gene rearrangements have now been shown not to be associated with LPL [7,8].

Differential diagnosis Strong cytoplasmic staining for immunoglobulin with light chain restriction alongside negativity for CD5 and cyclin D1 helps the distinction from CLL and mantle cell lymphoma (Fig 9.3). The monoclonal antibody VS38, recognising the rough endoplasmic reticulum protein p63, can also be useful in distinguishing LPL from other low-grade lymphomas that are usually negative [9,10]. Separation from marginal zone lymphoma is difficult and, it has to be said, is more a matter of personal opinion in our current state of knowledge.

PAS low power

PAS Dutcher body

Fig 9.1 Typical low and high power views of lymphoplasmacytic lymphoma with examples of both haematoxylin and eosin (H&E) and periodic acid–Schiff (PAS) stains. The latter can be helpful in highlighting the plasmacytoid differentiation and the intranuclear Dutcher bodies (arrowed in both H&E and PAS).

Heavy chain diseases These are a group of very rare lymphoplasmacytoid diseases in which the lymphoma cells only express a single heavy

IgM

p63 protein (VS38)

Lambda

Kappa

Fig 9.2 Immunostains showing the cytoplasmic reactivity in lymphoplasmacytic lymphoma for IgM with light chain restriction (λ in this case). Detection of the p63 protein with VS38 can also be helpful in differential diagnosis, but bear in mind that this antigen is present on all endoplasmic reticulum so other cells such as endocrine cells, osteoclasts and stromal cells are also positive.

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Lymphoplasmacytic Lymphoma

Table 9.1 Immunophenotypes of lymphoplasmacytic lymphoma compared with its main differential diagnoses

Lymphoplasmacytic lymphoma Chronic lymphocytic leukaemia Mantle cell lymphoma Follicular lymphoma Marginal zone lymphoma Splenic marginal zone lymphoma

IgM

IgD

CD5

CD10

CD23

CD43

bcl-6

Cyclin D1

+ (+) + + + +

− (+) ± ± − +

− + + − − −

− + −

± + ± ± ±

± + + − ± −

− − − + − −

− − + − − −

CD20

H&E

CD79a

Kappa Fig 9.3 Example of a case received in consultation with a differential diagnosis of reactive lymphocytosis versus non-specific non-Hodgkin lymphoma. Immunostaining identifies it as lymphoplasmacytic lymphoma secreting abundant κ-positive immunoglobulin. CD5, CD23 and cyclin D1 were negative.

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chain γ, μ or α without an accompanying light chain. They are easily confused with other low-grade lymphoproliferations and usually only come to light with an extended immunophenotype revealing the unusual heavy chain expression without any light chain expression. The α variant is slightly more common than the other two and involves the gastrointestinal tract in young adults. It is also known as immunoproliferative small intestinal disease and is generally believed to be a variant of extranodal marginal zone lymphoma (mucosa-associated lymphoid tissue or MALT).

Prognosis and treatment The clinical course is similar to CLL being slowly progressive and little affected by current therapy.

References 1. Harris N, Bhan A. B-cell neoplasms of the lymphocytic, lymphoplasmacytoid, and plasma cell types: immunohistologic analysis and clinical correlation. Hum Pathol 1985;16:829–37. 2. Pangalis G, Nathwani B, Rappaport H. Malignant lymphoma, well differentiated lymphocytic: its relationship with chronic lymphocytic leukemia and macroglobulinemia of Waldenstrom. Cancer 1977;39:999.

Lymphoplasmacytic Lymphoma

3. Gertz MA, Fonseca R, Rajkumar SV. Waldenström’s macroglobulinemia. Oncologist 2000;5:63–7. 4. Dimopoulos MA, Galani E, Matsouka C. Waldenström’s macroglobulinemia. Hematol Oncol Clin North Am 1999;13:1351–66. 5. Patsouris E, Noel H, Lennert K. Lymphoplasmacytic/ lymphoplasmacytoid LPL with a high content of epithelioid cells: histologic and immunohistochemical findings. Am J Surg Pathol 1990;14:660–70. 6. Konoplev S, Medeiros LJ, Bueso-Ramos CE, Jorgensen JL, Lin P. Immunophenotypic profile of lymphoplasmacytic lymphoma/ Waldenstrom macroglobulinemia. Am J Clin Pathol 2005;124: 414–20. 7. Cook JR, Aguilera NI, Reshmi-Skarja S, et al. Lack of PAX5 rearrangements in lymphoplasmacytic lymphomas: reassessing the reported association with t(9;14). Hum Pathol 2004;35: 447–54. 8. George TI, Wrede JE, Bangs CD, Cherry AM, Warnke RA, Arber DA. Low-grade B-Cell lymphomas with plasmacytic differentiation lack PAX5 gene rearrangements. J Mol Diagn 2005; 7:346–51. 9. Turley H, Jones M, Erber W, Mayne K, de Waele M, Gatter K. VS38: a new monoclonal antibody for detecting plasma cell differentiation in routine sections. J Clin Pathol 1994;47: 418–22. 10. Banham AH, Turley H, Pulford K, Gatter K, Mason DY. The plasma cell associated antigen detectable by antibody VS38 is the p63 rough endoplasmic reticulum protein. J Clin Pathol 1997;50:485–9.

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Plasmacytoma/Myeloma

Introduction Multiple myeloma is a clinical entity caused by a malignant monoclonal proliferation of plasma cells within the bone marrow. It is characterised by: • increased numbers of clonal plasma cells within the bone marrow (>10% of the nucleated cell population) • end-organ damage: – hypercalcaemia – renal insufficiency – anaemia – lytic bone lesions • the presence of an M (or paraprotein) band identified electrophoretically in serum (usually >30 g/L) or urine. At least two of these three components must be present before a diagnosis of myeloma can be made.

Clinical features The most common clinical features associated with myeloma are bone pain and pathological fractures, fatigue caused by anaemia and renal failure. Hyperviscosity and hypercalcaemia may occasionally cause symptoms such as altered consciousness or blurred vision. Some patients may have additional complications from amyloidosis.

Histology Myeloma is characterised by a proliferation of clonal plasma cells in the marrow (Fig 10.1). Typically the neoplastic plasma cells have many abnormal features including binucleated and immunoblastic forms. The more blastic forms of myeloma are believed to signal a poorer prognosis. Myeloma cells are often patchily distributed around the marrow in clusters rather than the single cell layers around blood vessels, as seen with reactive plasma cells. Amyloid deposition is commonly found around vessels in many organs (kidney, gut, spleen, liver) which if extensive enough

may give rise to the clinical syndrome of amyloidosis (of AL type) (Figs 10.2 and 10.3). Myeloma cells are not usually involved with the amyloid and if plasma cells are present they are polyclonal with benign cytologies.

Blood involvement It is very uncommon to detect circulating myeloma cells in blood films. Clonal plasma cells constituting more than 20% of peripheral white cells are considered to represent plasma cell leukaemia. This is a very rare variant of myeloma and has a poor prognosis.

Immunophenotype For the pathologist the most useful markers are antibodies against heavy and light chains together with a plasma cell marker such as the VS38 (p63 antigen) [1], CD38 or CD138/ syndecan 1 [2]. In difficult to interpret or poorly fixed, badly staining cases in situ hybridisation for light chain RNA can be very useful. Although of B-cell lineage most B-cell antigens other than CD79a are absent, although some lightchain-secreting myeloma cells may be positive for both CD20 and CD45. CD56 is positive on 70–80% of cases [3,4]. Myeloma cells may on occasion express a number of ‘unexpected’ antigens such as cytokeratins, epithelial membrane antigen (EMA), CD117 or CD10 which can cause diagnostic errors if not appreciated. Myeloma also commonly expresses nuclear cyclin D1 staining although this is unlikely to lead to confusion with mantle cell lymphoma [5].

Cytogenetics A variety of translocations and cyclin D upregulations have been combined into an eight-group algorithm that gives an overview of good or bad prognosis [6]. At the moment pathologists can broadly mirror this as the 50% or

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Fig 10.1 Typical clonal myeloma in the bone marrow with an example of the plasmablastic variant at bottom right.

Plasmacytoma/Myeloma

Giemsa

H&E

Lambda

Kappa

p63 (VS38)

Plasmablastic variant

so of cyclin D1+ cases have a better survival than negative cases [7].

Differential diagnosis In bone marrow, the differential diagnosis is usually reactive plasmacytosis but this problem is generally solved by immunohistochemistry which shows polytypic Ig-secreting plasma cells. Another diagnostic difficulty is represented by a bone marrow trephine biopsy performed in patients with mild monoclonal gammopathy (so-called MGUS or monoclonal gammopathy of uncertain significance). In these patients one sees a moderate or minimal bone marrow involvement (<10%) by monotypic Ig-secreting plasma cells without clear morphological abnormalities. This diagnostic difficulty cannot usually be solved by immunomorphology alone and requires clinicopathological correlations (basically these patients do not meet the minimum clinical criteria for a diagnosis of myeloma).

Plasma cells tumours may also occur in extraskeletal sites and the term ‘plasmacytoma’ is commonly used after appropriate staging investigations to exclude myeloma. Plasmacytomas may arise in a lymph node, tonsil, skin, upper respiratory tract or gastrointestinal tract (Fig 10.4). In lymph node, plasmacytomas usually consist of almost normal appearing but monoclonal plasma cells associated with scattered atypical cells with large nuclei, but with the same chromatin pattern as typical plasma cells. A pseudoangiomatous pattern is frequently observed. Amyloid deposits with foreign-body giant cells have also been described. Patients with POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy and skin changes) syndrome, frequently seen in association with the plasma cell variant of Castleman disease, often have deposits of osteosclerotic plasmacytomas as single or multiple lesions in their bone marrows. The number of plasma cells in these may be relatively low but they are monotypic for immunoglobulins and virtually always restricted for λ light chains [8].

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Plasmacytoma/Myeloma

Fig 10.2 Amyloid deposition in the spleen (top) and in a localised plasmacytoma in the larynx (bottom) with a multinucleated cell reaction.

Solitary bone tumours have also been described. In this case the main difficulty is to rule out a bone tumour associated with multiple myeloma. The best criterion supporting the diagnosis of a solitary bone plasmacytoma is the lack of plasma cell infiltration on bone marrow biopsy distant from the bone tumour and the disappearance of the M component after treatment of the plasma cell bone tumour [9].

Prognosis and treatment The clinical course is one of remission after chemotherapy but with eventual relapse into more high-grade disease which is then less responsive to further chemotherapy. Poor prognostic features include plasmablastic forms of myeloma and high degrees of marrow infiltration. An indolent form, known as smouldering myeloma, has been described that meets the laboratory criteria for myeloma but does not display any end-organ damage. Patients may be symptom

98

Lambda

Kappa

Fig 10.3 AL amyloid in the small intestine associated with a λ-producing myeloma in the bone marrow. Note the presence of plasma cells of both light chain classes in the gut with soluble κ immunoglobulin in the vessel lumina (arrowed above).

free for many years although progression to frank myeloma is common with time [10]. Many new modalities of treatment are being actively researched in the search for a better outcome in myeloma, including various forms of bone marrow transplantation, biologic therapies such as velcade, thalidomide and lenalidomide, and monoclonal antibody therapies [11,12].

CHAPTER 10

Plasmacytoma/Myeloma

HE

VS38

κ

κ in situ

λ

λ in situ

Fig 10.4 Example of a solitary deposit of plasmacytoma in the skin with the morphology and plasma cell nature shown by H&E and antibody VS38 (top row). Light chain restriction for κ light chains is shown below with both immunostains (left column) and in situ for light chain RNA (right column).

References 7. 1. Turley H, Jones M, Erber W, Mayne K, de Waele M, Gatter K. VS38: a new monoclonal antibody for detecting plasma cell differentiation in routine sections. J Clin Pathol 1994;47:418–22. 2. Costes V, Magen V, Legouffe E, et al. The Mi15 monoclonal antibody (anti-syndecan-1) is a reliable marker for quantifying plasma cells in paraffin-embedded bone marrow biopsy specimens. Hum Pathol 1999;30:1405–11. 3. Van Camp B, Durie B, Spier C, et al. Plasma cells in multiple myeloma express a natural killer cell-associated antigen: CD56 (NHK-1; Leu-19). Blood 1990;76:377–82. 4 4, Harrington AM, Hari P, Kroft SH. Utility of CD56 immunohistochemical studies in follow-up of plasma cell myeloma. Am J Clin Pathol 2009;132:60–6. 5. Hoechtlen-Vollmar W, Menzel G, Bartl R, Lamerz R, Wick M, Seidel D. Amplification of cyclin D1 gene in multiple myeloma: clinical and prognostic relevance. Br J Haematol 2000;109:30–8. 6. Bergsagel PL, Kuehl WM. Molecular pathogenesis and a conse-

8. 9.

10.

11. 12.

quent classification of multiple myeloma. J Clin Oncol 2005;23: 6333–8. Cook JR, Hsi ED, Worley S, Tubbs RR, Hussein M. Immunohistochemical analysis identifies two cyclin D1+ subsets of plasma cell myeloma, each associated with favorable survival. Am J Clin Pathol 2006;125:615–24. Dispenzieri A, Kyle RA, Lacy MQ, et al. POEMS syndrome: definitions and long-term outcome. Blood 2003;101:2496–506. Dimopoulos MA, Moulopoulos LA, Maniatis A, Alexanian R. Solitary plasmacytoma of bone and asymptomatic multiple myeloma. Blood 2000;96:2037–44. Criteria for the classification of monoclonal gammopathies, multiple myeloma and related disorders: a report of the International Myeloma Working Group. Br J Haematol 2003;121:749–57. Kyle RA, Rajkumar SV. Treatment of multiple myeloma: a comprehensive review. Clin Lymphoma Myeloma 2009;9:278–88. Nair B, van Rhee F, Shaughnessy JD Jr, et al. Superior results of total therapy 3 (2003-33) in gene expression profiling-defined low-risk multiple myeloma confirmed in subsequent trial 200666 with VRD maintenance. Blood 2010;115:4168–73. 99

11

Marginal Zone B-cell Lymphoma (Extranodal Malt and Nodal Types) and Extranodal Malt Lymphoma

These lymphomas have a relatively heterogeneous population of lymphoid cells, including lymphocytes, centrocytelike cells and plasmacytoid cells. Their special characteristic is that they arise in mucosal sites such as the gut where they remain localised for long periods before disseminating to lymph nodes and bone marrow [1,2]. Hence the acronym MALT for lymphomas of mucosa-associated lymphoid tissue.

Clinical features MALT lymphomas typically arise in the gastrointestinal tract or other glandular epithelial tissues. Gastric MALT lymphoma is usually associated with helicobacter infection and may respond to appropriate antibiotic therapy [3,4]. In other sites there may be an association with autoimmune conditions such as Sjögren syndrome or Hashimoto thyroiditis. Borrelia burgdorferi has been proposed as a similar stimulating antigen in some cases of cutaneous marginal zone lymphoma [5,6].

Histology The diagnosis is made by clinicopathological correlation as well as microscopy. The cell population is a mixture of small lymphocytes, plasmacytoid cells and centrocyte-like lymphocytes and is easily confused with other low-grade lymphomas, especially lymphoplasmacytic lymphomas. In some cases the lymphoma cells have a monocytoid appearance. A characteristic feature is the presence of invasive epithelial lesions (the so-called lymphoepithelial lesions) (Figs 11.1 and 11.2). Epithelial cells derived from these, often with

acidophilic cytoplasm, are commonly found scattered among lymphoid cells. Within the mucosa there may be large prominent reactive lymphoid follicles that are progressively colonised and replaced by the lymphoma. Helicobacter pylori can be demonstrated in most cases of gastric MALT lymphoma (Fig 11.3). It should be emphasised that lymphoepithelial lesions are not seen in all cases of MALT lymphoma in any site. They are uncommon in large cell transformations and in MALTs in the eye, skin or breast. Furthermore they may be seen in benign inflammatory lesions such as gastritis. Large cell transformation does occur both with disease progression and at diagnosis and exhibits a more aggressive course, justifying a label of high-grade lymphoma [7]. This should be diagnosed only when there is prior or coexisting evidence of low-grade marginal zone lymphoma, although the 2008 WHO classification emphasises that this transformation should be called diffuse large B-cell lymphoma and that the term ‘high-grade MALT’ lymphoma should not be used to avoid confusion with what is in essence a low-grade lesion. It is important to note that scattered large B cells (centroblasts or immunoblasts) are commonly seen in MALT lymphomas and do not indicate a diagnosis of large cell lymphoma transformation which requires the presence of sheets of large cells. Secondary involvement of local lymph nodes is not uncommon. The tumour cells have a characteristic marginal zone and perisinusoidal pattern, which spreads with time to become more diffuse (Fig 11.4) [8].

Blood involvement Involvement of the peripheral blood or bone marrow is rare until late in the progression of the disease.

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Lymphoepithelial lesions

Cytokeratin

CD20

Fig 11.1 Typical gastric MALT (mucosa-associated lymphoid tissue) lymphoma showing lymphoepithelial lesions highlighted by immunostaining.

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H&E low power

H&E lymphoepithelial lesion

Fig 11.3 Helicobacter pylori can often be seen on H&E sections but are most easily demonstrated by immunostaining.

[9] and there have been two case reports of CD10 positivity [10]. Cytokeratin staining is useful for demonstrating lymphoepithelial lesions. In approximately 40% of cases the plasma cells secrete monotypic immunoglobulin (IgM > IgG or IgA).

Kappa

Lambda

Cytogenetics

Fig 11.2 MALT (mucosa-associated lymphoid tissue) lymphoma in the thyroid demonstrating monoclonal plasma cells and lymphoepithelial lesions.

Trisomy 3 and 18, although not specific, are common in MALT lymphomas [11]. A number of chromosomal translocations have been described, including t(1;14),t(3;14), t(11;18) and t(14;18). Their frequency varies considerably in different geographical and anatomical sites, suggesting that local and environmental factors play an aetiological role [12,13]. The translocation t(1;14) is associated with translocation of the bcl-10 gene which has further been shown to undergo mutations in 6–8% of MALT lymphomas, the higher figure being associated with large cell transformations [14]. The t(11;18) translocation occurs in about 25% of cases and results in the fusion of the API2 gene (an inhibitor of apoptosis) on chromosome 11 and the MALT1 gene on chromosome 18 [15]. Clinical studies have shown that its presence is related to a poor response to helicobacter treatment and chemotherapy but not to rituximab responsiveness [16].

Immunophenotype (Table 11.1) Tumour cells express several B-cell associated antigens (CD20, CD79a) and are typically negative for CD5, CD43, CD23 and CD10. As exceptions a few cases with a more aggressive clinical phenotype have been reported as CD5+

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Differential diagnosis MALT gastric lymphoma can be difficult to differentiate from dense reactive lymphoid infiltrates. However, in

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H&E low power

Early follicular colonisation

Late follicular colonisation

bcl-2 protein

Fig 11.4 Pattern of lymph node infiltration seen with both primary and secondary marginal zone lymphoma (MZL) (this case is secondary), showing both early and late colonisation of the lymphoid follicles. The early colonisation is highlighted by bcl-2 staining.

Table 11.1 The immunophenotypes of marginal zone lymphoma compared with its main differential diagnoses.

Marginal zone lymphoma Follicular lymphoma Mantle cell lymphoma Lymphoplasmacytic lymphoma Chronic lymphocytic leukaemia Splenic marginal zone lymphoma

IgM

IgD

CD5

CD10

CD23

CD43

bcl-6

Cyclin D1

+ + + + (+) +

− ± ± − (+) +

− − + − + −

− + − − − −

± ± − ± + ±

± − + ± + −

− + − − − −

− − + − − −

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HE

HE

CD79a

CD23

bcl2

CD10

bcl6

mib1

Fig 11.5 An example of a nodular MALT (mucosa-associated lymphoid tissue) lymphoma in which the cytology within the nodules looks like a follicular lymphoma due to the admixture of residual germinal centre cells. The MALT lymphoma can be seen to reside both within and outwith the follicles by B-cell staining (CD79a). The residual follicular structure is outlined by CD23 staining. It can be seen that the colonised follicles are bcl2, CD10 and bcl6 negative and have a much higher proliferative rate than a typical follicular lymphoma.

non-neoplastic infiltrates, lymphocytes seen within gastric glands are mainly of T-cell phenotype and the glands are not usually destroyed as in MALT lymphoma (emphasising the diagnostic value of cytokeratin staining). One of the most difficult differential diagnoses is to differentiate MALT lymphoma from lymphoplasmacytic lymphoma. There is currently no easy way to do this. On clinicopathological grounds the current tendency is to consider that most, if not all, of these cases in extranodal sites are MALT lymphoma with plasmacytic differentiation, rather than lymphoplasmacytic lymphoma as thought in the past. Apart from lymphoplasmacytic lymphoma, MALT lymphoma is easily confused with other low-grade lymphomas, especially mantle cell lymphoma. MALT lymphoma cells are characteristically negative for CD5, CD43, CD23 and cyclin D1 (thus excluding B-cell chronic lymphocytic leukaemia [B-CLL] and mantle cell lymphoma). A prominent nodular pattern may suggest a diagnosis of follicular lymphoma especially if the marginal zone cells have colonized the residual follicles (Fig 11.5). Although these MALT lymphomas are usually identified by their negativity for CD10 they can be puzzling because the colonized cells often lose their bcl2 positivity and become more highly proliferative than the cells left outside in the interstitial tissue [17].

Prognosis and treatment The clinical course may be entirely benign even in the absence of treatment. Most cases are slowly progressive with local recurrences often in other mucosal sites. Dissemination to nodes and bone marrow occurs late and some cases will terminate as large-cell lymphomas.

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In helicobacter-associated gastric maltomas, long remissions or even cures are being reported with appropriate antibiotic therapy [4,18]. Similar results are beginning to appear for Borrelia burgdorferi-associated cutaneous marginal zone lymphomas [19,20].

Nodal marginal zone B-cell lymphoma There had been controversy as to whether or not marginal zone lymphoma could arise primarily in a lymph node without a pre-existing extranodal component. On this basis it was categorised as a provisional entity in the REAL classification. Further studies are convincing that primary nodal cases, although rare, do exist without an associated MALT lymphoma. These cases have a similar if not identical architecture and morphology (including follicular colonisation) to that seen in secondary MALTs and to that previously described as a monocytoid B-cell lymphoma (Fig 11.6). A variety of patterns may be observed including diffuse, nodular, interfollicular, perifollicular and sinusoidal. A major differential diagnostic consideration in lymph nodes, particularly when the pattern is nodular, is follicular lymphoma with marginal zone differentiation [21]. The immunophenotype is identical to extranodal cases [22,23]. Nodal marginal zone lymphoma (MZL) can also undergo high-grade or large-cell transformation (Fig 11.7). A variant of nodal marginal zone lymphoma occurs in young boys, usually localised to their head and neck regions. It looks very similar except that the follicles usually show pronounced progressive transformation changes. This can cause considerable problems to distinguish the lymphoma from an atypical marginal zone hyperplasia, especially as this reactive condition can demonstrate monotypic Ig expression. Polymerase chain reaction for clonal rearrangements

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Marginal zone pattern

Colonised follicle

bcl-2

CD79a

Kappa

Lambda

Fig 11.6 A primary involvement of lymph node by marginal zone lymphoma (MZL) showing the marginal zone pattern, colonisation of follicles and monoclonal light chain restriction.

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Marginal Zone B-cell Lymphoma and Extranodal Malt Lymphoma is recommended for this distinction though the prognosis of both conditions is excellent after surgical removal [24].

References

Marginal zone pattern

Large cell transformation

CD20 Fig 11.7 Large cell transformation of a primary marginal zone lymphoma in a lymph node.

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1. Isaacson P, Wright D. Malignant lymphoma of mucosa associated lymphoid tissue. A distinctive B cell lymphoma. Cancer 1983;52:1410–16. 2. Isaacson P, Spencer J. Malignant lymphoma of mucosaassociated lymphoid tissue. Histopathology 1987;11:445–62. 3. Doglioni C, Wotherspoon AC, Moschini A, de Boni M, Isaacson PG. High incidence of primary gastric lymphoma in northeastern Italy [see comments]. Lancet 1992;339:834–5. 4. Wotherspoon A, Doglioni C, Diss T, et al. Regression of primary low-grade B-cell gastric lymphoma of mucosa-associated lymphoid tissue type after eradication of Helicobacter pylori. Lancet 1993;342:575–7. 5. Cerroni L, Zochling N, Putz B, Kerl H. Infection by Borrelia burgdorferi and cutaneous B-cell lymphoma. J Cutan Pathol 1997;24:457–61. 6. Garbe C, Stein H, Dienemann D, Orfanos CE. Borrelia burgdorferiassociated cutaneous B cell lymphoma: clinical and immunohistologic characterization of four cases. J Am Acad Dermatol 1991;24:584–90. 7. Chan J, Ng C, Isaacson P. Relationship between high-grade lymphoma and low-grade B-cell mucosa-associated lymphoid tissue lymphoma (MALToma) of the stomach. Am J Pathol 1990;136:1153–64. 8. Isaacson P, Spencer J. Monocytoid B-cell lymphomas. Am J Surg Pathol 1990;14:888–91. 9. Wenzel C, Dieckmann K, Fiebiger W, Mannhalter C, Chott A, Raderer M. CD5 expression in a lymphoma of the mucosaassociated lymphoid tissue (MALT)-type as a marker for early dissemination and aggressive clinical behaviour. Leuk Lymphoma 2001;42:823–9. 10. Millar EK, Waldron S, Spencer A, Braye S. CD10 positive thyroid marginal zone non-Hodgkin lymphoma. J Clin Pathol 1999;52:849–50. 11. Wotherspoon AC, Finn TM, Isaacson PG. Trisomy 3 in lowgrade B-cell lymphomas of mucosa-associated lymphoid tissue. Blood 1995;85:2000–4. 12. Streubel B, Simonitsch-Klupp I, Mullauer L, et al. Variable frequencies of MALT lymphoma-associated genetic aberrations in MALT lymphomas of different sites. Leukemia 2004;18: 1722–6. 13. Remstein ED, Dogan A, Einerson RR, et al. The incidence and anatomic site specificity of chromosomal translocations in primary extranodal marginal zone B-cell lymphoma of mucosaassociated lymphoid tissue (MALT lymphoma) in North America. Am J Surg Pathol 2006;30:1546–53. 14. Du MQ, Peng H, Liu H, et al. BCL10 gene mutation in lymphoma [in process citation]. Blood 2000;95:3885–90. 15. Remstein ED, James CD, Kurtin PJ. Incidence and subtype specificity of API2-MALT1 fusion translocations in extranodal, nodal, and splenic marginal zone lymphomas. Am J Pathol 2000;156:1183–8.

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16. Thieblemont C. Clinical presentation and management of marginal zone lymphomas. Hematology Am Soc Hematol Educ Program 2005:307–13. 17. Isaacson PG, Wotherspoon AC, Diss TC, Pan LX. Bcl-2 expression in lymphomas. Lancet 1991;337:175–6. 18. Neubauer A, Thiede C, Morgner A, et al. Cure of Helicobacter pylori infection and duration of remission of low-grade gastric mucosa-associated lymphoid tissue lymphoma. J Natl Cancer Inst 1997; 89:1350–5. 19. Kutting B, Bonsmann G, Metze D, Luger TA, Cerroni L. Borrelia burgdorferi-associated primary cutaneous B cell lymphoma: complete clearing of skin lesions after antibiotic pulse therapy or intralesional injection of interferon alfa-2a. J Am Acad Dermatol 1997;36(2 Pt 2):311–14. 20. Roggero E, Zucca E, Mainetti C, et al. Eradication of Borrelia burgdorferi infection in primary marginal zone B-cell lymphoma of the skin. Hum Pathol 2000;31:263–8.

21. Salama ME, Lossos IS, Warnke RA, Natkunam Y. Immunoarchitectural patterns in nodal marginal zone B-cell lymphoma: a study of 51 cases. Am J Clin Pathol 2009;132: 39–49. 22. Piris M, Rivas C, Morente M, Cruz M, Rubio C, Oliva H. Monocytoid B-cell lymphoma, a tumour related to the marginal zone. Histopathology 1988;12:383–92. 23. Ngan B-Y, Warnke R, Wilson M, Takagi K, Cleary M, Dorfman R. Monocytoid B-cell lymphoma: a study of 36 cases. Hum Pathol 1991;22:409–21. 24. Taddesse-Heath L, Pittaluga S, Sorbara L, Bussey M, Raffeld M, Jaffe ES. Marginal zone B-cell lymphoma in children and young adults. Am J Surg Pathol 2003;27:522–31.

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12

Follicular Lymphoma

Follicular lymphoma is the most common adult lymphoma in the USA and Europe, comprising 35–40% of all nonHodgkin lymphomas and 75–80% of low-grade B-cell lymphomas.

Clinical features Follicular lymphoma affects predominantly older adults, with an equal male : female incidence. Most patients have widespread disease at diagnosis, predominantly in lymph nodes, but also involving the spleen, bone marrow and occasionally peripheral blood or extranodal sites.

Histology Typically there is a nodular growth pattern, although this is more prominent in some cases than others and areas of diffuse growth may be seen (Fig 12.1). In contrast to reactive follicles, most follicular lymphomas lack mantle zones and macrophages containing phagocytosed cellular debris (the so-called tingible body macrophages of reactive germinal centres). Whether follicular lymphomas present with a completely diffuse infiltration pattern has been controversial. What one typically has to deal with is a lymphoma with the cytology of follicular lymphoma that looks diffuse, but usually has recognisable areas of nodularity after immunostaining (especially for follicular dendritic cells [FDCs]

with CD21 or CD23). Truly diffuse follicular lymphomas (negative for FDCs) were a provisional entity in the REAL classification [1] and have been accepted as a rare subtype in the 2008 WHO classification [2]. They are most commonly faced in needle biopsies where they may just represent a sampling problem. In practical terms there is no evidence that they behave any differently from regular follicular lymphomas. It is important to distinguish these rare diffuse cases from follicular lymphomas with diffuse areas of large cells. These are areas of large-cell transformation and should be identified as such as diffuse large B-cell lymphoma. Follicular lymphomas are composed of a mixture of centrocytes and centroblasts (also referred to respectively as ‘cleaved’ and ‘large non-cleaved’ follicle centre cells). Centrocytes usually predominate. Occasionally rare atypical cells (some may even be bi- or multinucleate) are observed in some follicles (Fig 12.2). Grading follicular lymphomas for clinical purposes has been controversial. The matter has been extensively discussed by the panels dealing with this tumour for both recent World Health Organization (WHO) classifications [2,3]. The current agreement is to continue to use the Mann and Berard counting method [4] of three grades as shown in Table 12.1. As a result of the poor interobserver reproducibility in this scheme and the lack of any clinical relevance, it is now acceptable to combine grades 1 and 2 and report a case as grade 1/2 follicular lymphoma. Grade 3 is split into grade 3A which has a mixture of centroblasts and

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

Follicular Lymphoma

Fig 12.1 Follicular lymphoma can demonstrate a wide range of architectural patterns ranging from a typical abnormal nodular pattern (a,b) through a variety of reactive nodule look-a-likes (c–f) to a marginal zone pattern (g) and an almost diffuse replacement of the node (h).

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Table 12.1 The Mann and Berard [4] counting method of three grades.

Fig 12.2 This figure illustrates the typical cytology of follicular lymphoma in which centrocytes (small cleaved cells) predominate over the larger centroblasts.

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Follicular lymphoma grading

Large cells per high power field

Grade Grade Grade Grade

0–5 6–15 >15 100%

1 2 3A 3B

centrocytes and grade 3B which contains only nodules of centroblasts [5]. A high power field is that observed through ×10 eyepieces and a ×40 objective and it is recommended that at least 10 fields are counted (Fig 12.3). It is accepted that this will vary slightly between different models of microscope. For current practical purposes only grade 3 has an additional clinical significance requiring high-grade lymphoma chemotherapy. Any diffuse areas of large cells should be reported separately as diffuse large B-cell lymphoma. The 2008 WHO classification is quite explicit about this, stating that the diagnosis should be reported as: 1. Diffuse large B-cell lymphoma (state % involved) 2. Follicular lymphoma (report grade and state % involved). For staging purposes the pathologist’s role is mainly in reading the bone marrow trephine because involvement is rarely seen in bone marrow smears or peripheral blood (Fig 12.4). According to the WHO classification it is also recommended to classify follicular lymphomas into three growth patterns: follicular (>75% nodular), follicular and diffuse (25–75% nodular) and predominantly diffuse (or minimally follicular <25% nodular) (Fig 12.5). Note that the presence of lymphoma cells in the interfollicular areas is a common finding and does not define diffuse areas [2]. Occasional cases show plasmacytoid differentiation or foci of cells with the appearance of ‘marginal zone’ or ‘monocytoid’ B cells. Periodic acid–Schiff (PAS)-positive material derived from the lymphoma cell membranes (CD20+, IgM+, CD10+) may also occasionally be detected [6]. Primary cutaneous follicular lymphoma is now listed as a separate entity in the 2008 WHO classification. It occurs mainly on the head and trunk. The lymphomas usually consist of larger cells (both centrocytes and centroblasts) than those observed in nodal follicular lymphoma and are often bcl-2 negative. It is important to ensure that the lesion is confined to the skin and not a secondary spread from a systemic lesion because primary cutaneous follicular lymphomas have an excellent prognosis and require little more

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Grade 1

Grade 2

Follicular Lymphoma

Grade 3

Fig 12.3 Examples of grading follicular lymphoma. Examples of grades 1, 2 and 3 follicular lymphoma are shown on the top. The figures on the bottom show similar fields all from the same tissue section of a single follicular lymphoma, emphasising that multiple fields must be sampled and common sense used in selecting them. In this particular example the field counted as grade 3 was unique in this otherwise grade 1 follicular lymphoma.

than local treatment. A detailed discussion of this topic may be found in a companion volume to this text dealing with cutaneous lymphoma [7].

Immunophenotype Follicular lymphoma cells usually express surface immunoglobulin. This is often IgM and less commonly IgG. It is of a single light chain type, reflecting the monoclonal nature of the tumour. The tumour cells also express pan-B-cell associated antigens (CD20, CD79a) and most (more than 85%) are bcl-2 and bcl-6 positive [8–11]. Bcl2 negativity may be related to mutations that are not picked up by the most commonly used antibody bcl2/-124 but may be identified by alternative anti-bcl-2 antibodies. Negativity is also related to increased proliferation and is seen more commonly in grade 3 subtypes [12]. CD10 is an important marker, being present on 70–80% of cases and is especially useful when it is positive on interstitial B cells as well as on the nodules [13,14]. CD10 negativity tends to be more frequent on grade 3 cases [15]. In addition CD10 may be expressed only in the intrafollicular component in some cases and other germinal centre markers such as bcl-6, HGAL and LMO2 may be useful in labelling the interfollicular component to provide support for a diagnosis of follicular lymphoma in such difficult cases. None of these germinal centre markers is typically expressed in bone

marrow infiltrates of follicular lymphoma. CD23 may be present in up to a third of cases whereas CD5+ and CD43+ cases are rare [16–18]. Tightly organised meshworks of FDCs are present in follicular areas. These are responsible for the follicular pattern of these tumours. In follicular and diffuse cases, the FDCs are absent or scattered singly in the diffuse areas with FDC meshworks being seen only in follicular areas (Table 12.2 and Fig 12.6).

Cytogenetics and molecular biological features A translocation t(14;18), involving rearrangement of the bc1-2 gene, is present in at least two-thirds of all cases, the frequency being greatest in cases of grade I and II. This translocation occurs at an early stage of B-cell development, during immunoglobulin gene rearrangement [19,20] and is now readily detectable by fluorescence in situ hybridisation (FISH) on paraffin sections (Fig 12.7). This results in expression of the ‘anti-apoptosis’ bcl-2 gene, which is not expressed in normal germinal centre cells. Expression of the bcl-2 protein permits accumulation of long-lived centrocytes. Occasional cells with rearranged bcl-2 genes can be detected in lymphoid tissues and peripheral blood lymphocytes in some normal individuals. Thus, when a resting B cell that carries the bcl-2 translocation undergoes

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Follicular Lymphoma blast transformation in response to antigen, failure to switch off the bcl-2 gene may contribute to development of a lymphoma [21].

Variants and subtypes The 2008 WHO classification lists four of these.

1. Paediatric follicular lymphoma This is very rare but usually presents as localised head and neck lymphoid disease. Morphologically it looks identical to adult disease except that it is frequently of grade 3 cytology, lacks bcl-2 expression and t(14;18) (Fig 12.8). The prognosis after treatment is generally excellent apart from the minority of cases that are bcl-2+ and do badly [22].

Giemsa low-power

2. Primary intestinal follicular lymphoma These are typical follicular lymphomas that occur most commonly in the duodenum (Fig 12.9). The disease is localised and patients do very well even without treatment.

3. Other extranodal follicular lymphomas These are again typical follicular lymphomas and can occur in almost any other site. They are usually localized with an excellent prognosis.

4. Intrafollicular neoplasia/‘in situ’ follicular lymphoma

B cell CD79a low-power

This is an unusual event mostly found in reactive lymph nodes removed for other diagnostic reasons. A typical case is illustrated in Fig 12.10. Most of these patients are well and have no other evidence of follicular lymphoma. Clinical data on these is sparse; some have systemic disease, others have developed follicular lymphoma with time, but so far most reported cases have remained well over relatively long periods [23].

Differential diagnosis All lymphoproliferations with a follicular or nodular pattern may mimic follicular lymphoma.

Reactive follicular hyperplasia (see Chapter 2)

B cell CD79a high-power Fig 12.4 Bone marrow involvement by follicular lymphoma typically has a paratrabecular localisation, often best appreciated by B-cell staining (here shown by CD79a). Such immunostaining also allows at higher power an appreciation of the predominantly centrocytic cytology.

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These lesions are frequently encountered in lymphoid pathology and are the most common differential diagnosis of follicular lymphoma. Usually, no aetiology is found and these lesions are diagnosed as non-specific follicular hyperplasia. In follicular lymphoma, in contrast to follicular hyperplasia, malignant follicles lack mantle zones and macrophages with tingible bodies. However, in occasional cases, malignant follicles are surrounded, at least partially, by mantle zones, making the lesion very difficult to distinguish from hyperplasia. An even more difficult scenario comes

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Follicular Lymphoma

Fig 12.5 In this example a patient presented with a typical nodular grade 1 follicular lymphoma (FL) (upper images) which responded to single agent chemotherapy but relapsed as a high-grade transformation 10 years later (lower images). In the same relapse specimen, areas of typical grade 1 FL could be identified. The diagnosis was therefore diffuse large B-cell lymphoma 90% with FL grade 1–10%.

Table 12.2 The immunophenotypes of follicular lymphoma compared with its main differential diagnoses.

Follicular lymphoma Mantle cell lymphoma Lymphoplasmacytic lymphoma Chronic lymphocytic leukaemia Marginal zone lymphoma Splenic marginal zone lymphoma

IgM

IgD

CD5

CD10

CD23

CD43

bcl-6

Cyclin D1

+ + + (+) + +

± ± − (+) − +

− + − + − −

+ − − − − −

± − ± + ± ±

− + ± + ± −

+ − − − − −

− + − − − −

with a follicular lymphoma partially involving a reactive lymph node, especially when follicular lymphoma cells colonise reactive follicles. Immunohistochemistry (sometimes supplemented by molecular techniques) is then required for differentiating these two lesions. Both reactive and neoplastic follicles consist of a predominant population of B cells expressing CD20 and CD79a and are surrounded by CD3+ small T-cell lymphocytes. However, in follicular lymphoma, even with preserved mantle zones, there is a clear increase of B cells (mostly neoplastic and often being CD10+) in the interfollicular area, a finding that is useful in diagnosis. For the histopathologist the most helpful reagent to distinguish reactive lymphoid hyperplasia from follicular lymphoma is the anti-bcl-2 antibody [24]. However, 15–20% of follicular

lymphomas are negative for bcl-2 (Fig 12.11). Another aid is given by the proliferation rate staining (Ki-67 or similar), the pattern of which is scattered or targetoid in follicular lymphomas, unlike the neatly zoned and usually much higher rate seen in reactive germinal centres (Fig 12.12) [25]. With careful attention to technique, light chain restriction can be demonstrated on follicular lymphomas, whereas of course hyperplastic follicles are polytypic (Fig 12.13). In some cases frozen sections may be required for the demonstration of such clonality.

Castleman tumour (see Chapter 2) This benign tumour is usually distinctive but may be confused with a sclerosed follicular lymphoma. A complete immunophenotype will normally clarify the diagnosis

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CD20

bcl-2

CD3

Ki67

CD10

Fig 12.6 The typical immunophenotype of follicular lymphoma. Note the low proliferation rate (Ki67), significant numbers of CD10+ interfollicular B cells (CD20) and bcl2 positivity. It is always important to perform a CD3 stain to ensure bcl2 is on the neoplastic B cells as well as reactive T cells. These are key features distinguishing follicular lymphoma from reactive hyperplasia.

Bcl2 breakapart probes

Fig 12.7 Fluorescence in situ hybridisation (FISH) for the t(14;18) using break-apart probes (arrowed) on paraffin sections.

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HE

HE

CD20

CD10

bcl6

bcl2

Fig 12.8 Typical paediatric follicular lymphoma with large follicles, some with an appearance reminiscent of progressive transformation of germinal centres. The nodules are composed of centrocytes and centroblasts with a grade 3A appearance. The nodules are CD20+, CD10+, bcl-6 +, but bcl-2−.

HE

CD20

CD10

Fig 12.9 Intestinal follicular lymphoma in duodenum showing a nodular and diffuse pattern which is CD20+ and CD10+.

because the nodules are polytypic in Castleman disease, which also characteristically contains clusters of CD68+ plasmacytoid monocytes/dendritic cells in the interfollicular areas.

In contrast to mantle cell lymphomas, follicular lymphomas are CD10+ and bcl-6+ in most cases and negative for CD5, cyclin D1 and usually CD43 as well.

Mantle cell lymphoma

Nodular lymphocyte-predominance Hodgkin lymphoma (see Chapter 27)

Mantle cell lymphoma showing a nodular pattern may on superficial examination simulate follicular lymphoma. Follicular dendritic meshworks are present in both tumours.

Nodular lymphocyte-predominance Hodgkin lymphoma (NLPHL) is sometimes misdiagnosed as either follicular lymphoma or atypical follicular hyperplasia because of the

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Follicular Lymphoma

Dermatopathic change

CD1a

Abnormal follicles

bcl-2 protein

Fig 12.10 An example of ‘in situ’ follicular lymphoma manifesting as follicular colonisation of a few follicles in an otherwise reactive node showing dermatopathic changes secondary to a skin rash. The bcl-2 positivity and the proliferation pattern are crucial for the diagnosis.

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CD10

Follicular Lymphoma

Proliferation (Ki-67)

Fig 12.10 (continued)

B cell

bcl-2

Kappa

Lambda

Fig 12.11 An example of an otherwise unremarkable FL being negative for bcl-2 protein. There is no strict relationship bewteen bcl-2 negativity and the t(14;18) translocation: some negative cases have the translocation and vice versa.

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Fig 12.12 The pattern of proliferation (Ki67) is characteristic in follicular lymphomas. Here is an example at low power (left) of reactive follicles (upper part of the image) with a high, zoned pattern contrasting with the broken up targetoid pattern of a follicular lymphoma (lower part of the image). This is shown at higher power (middle) and even when the proliferation rate is high in a follicular lymphoma the pattern is still quite abnormal and distinctive (right).

presence of progressively transformed germinal centres. The pattern of nodularity may be more easily recognised after immunostaining for FDCs or with anti-B-cell antibodies. Anti-IgD staining will show the expanded mantle zones in NLPHL. Although occasional large atypical cells can be seen in follicular lymphoma, they are not as numerous as those usually seen in NLPHL. Although the LP cells of NLPHL are of B-cell phenotype they differ from follicular lymphoma cells by often being positive for epithelial membrane antigen (EMA) and Oct-2 (an immunoglobulin gene regulator) but negative for CD10. Characteristically, LP cells are surrounded by a wreath or rosette of CD57+ T cells. A most important distinguishing feature is that the background small B cells are clonal in follicular lymphoma whereas they are polytypic in NLPHL.

Prognosis and treatment There have been attempts in the past to divide follicular lymphoma into distinct subtypes, on the basis of the proportion of centroblasts and the size of the centrocytes. However, in reality there is a continuous gradation in the number of

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large cells. So the terms ‘follicular lymphoma grades 1, 2 and 3’ represent an arbitrary division of a spectrum. Grading follicular lymphomas is poorly reproducible. The ‘cell counting’ method of Mann and Berard [4] has been shown to be more reproducible than other methods and it may offer some indication of prognosis [26,27]. For this reason it has been adopted as described above by the WHO classification. The proportions of follicular and diffuse areas vary from case to case. In follicular large-cell (grade 3A and 3B) lymphoma, diffuse areas occupying more than 25% of the tissue signify a poorer outcome. Many factors and markers have been postulated as conferring prognostic information, including biomarkers such as bcl-2, CD10 and MUM1, infiltration by lymphocytes or macrophages, vascular growth and pattern, and proliferative index. Each has its protagonists and unfortunately the literature is replete with conflicting results [28]. None has yet been included in the international prognostic index which is based on clinical features alone and is a strong predictor of outcome [29]. All of these studies may well become irrelevant because the introduction of antiCD20 therapy (rituximab) with conventional chemotherapy has so changed the outlook for follicular lymphoma that it can now be argued that it has become a curable disease [30].

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Follicular Lymphoma

References

HE low power

HE high power

CD3

bcl-2

CD10

Lambda

Kappa Fig 12.13 Careful immunocytochemistry will distinguish a reactive hyperplasia from a follicular lymphoma (FL). A point that should be emphasised is that it is worth staining for CD3 to ensure that the bcl-2+ cells in the nodules are FL cells and not infiltrating reactive T cells. In this case light chain staining has been successful in demonstrating κ restriction but it is important to look carefully at the sections to detect the cytoplasmic dot positivity. Otherwise it is easy to dismiss the staining as non-reactive.

1. Harris NL, Jaffe ES, Stein H, et al. A revised European–American classification of lymphoid neoplasms: a proposal from the International Lymphoma Study Group [see comments]. Blood 1994;84:1361–92. 2. Swerdlow SH, Campo E, Harris NL, et al., eds. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 4th edn. Lyon: IARC Press, 2008. 3. Jaffe ES, Harris NL, Stein H, Vardiman JW, eds. Pathology and Genetics of Tumours of Haematopoietic and Lymphoid Tissues. Lyon: IARC Press, 2001. 4. Mann R, Berard C. Criteria for the cytologic subclassification of follicular lymphomas: a proposed alternative method. Hematological Oncology 1982;1:187–92. 5. Bosga-Bouwer AG, van den Berg A, et al. Molecular, cytogenetic, and immunophenotypic characterization of follicular lymphoma grade 3B; a separate entity or part of the spectrum of diffuse large B-cell lymphoma or follicular lymphoma? Hum Pathol 2006;37:528–33. 6. Chittal S, Caverivière P, Voigt J, et al. Follicular lymphoma with abundant PAS-positive extracellular material. immunohistochemical and ultrastructural observations. Am J Surg Pathol 1987;11:618–24. 7. Cerroni L, Gatter KC, Kerl H. Skin Lymphoma: The illustrated guide. Oxford: Wiley-Blackwell, 2009. 8. Gaulard P, d’Agay M, Peuchmaur M, et al. Expression of the bcl-2 gene product in follicular lymphoma. Am J Pathol 1992; 140:1089–95. 9. Pezzella F, Tse AG, Cordell JL, Pulford KA, Gatter KC, Mason DY. Expression of the bcl-2 oncogene protein is not specific for the 14;18 chromosomal translocation. Am J Pathol 1990;137: 225–32. 10. Ree HJ, Kadin ME, Kikuchi M, Ko YH, Suzumiya J, Go JH. Bcl-6 expression in reactive follicular hyperplasia, follicular lymphoma, and angioimmunoblastic T-cell lymphoma with hyperplastic germinal centers: heterogeneity of intrafollicular T-cells and their altered distribution in the pathogenesis of angioimmunoblastic T-cell lymphoma. Hum Pathol 1999;30:403–11. 11. Falini B, Fizzotti M, Pileri S, Liso A, Pasqualucci L, Flenghi L. Bcl-6 protein expression in normal and neoplastic lymphoid tissues. Ann Oncol 1997;8(suppl 2):101–4. 12. Masir N, Campbell LJ, Goff LK, et al. BCL2 protein expression in follicular lymphomas with t(14;18) chromosomal translocations. Br J Haematol 2009;144:716–25. 13. Dogan A, Bagdi E, Munson P, Isaacson PG. CD10 and BCL-6 expression in paraffin sections of normal lymphoid tissue and B-cell lymphomas. Am J Surg Pathol 2000;24:846–52. 14. Barcus ME, Karageorge LS, Veloso YL, Kornstein MJ. CD10 expression in follicular lymphoma versus reactive follicular hyperplasia: evaluation in paraffin-embedded tissue. Appl Immunohistochem Mol Morphol 2000;8:263–6. 15. Eshoa C, Perkins S, Kampalath B, Shidham V, Juckett M, Chang CC. Decreased CD10 expression in grade III and in interfollicular infiltrates of follicular lymphomas. Am J Clin Pathol 2001;115:862–7. 16. Lai R, Weiss LM, Chang KL, Arber DA. Frequency of CD43 expression in non-Hodgkin lymphoma. A survey of 742 cases

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17.

18.

19.

20.

21.

22.

23.

Follicular Lymphoma

and further characterization of rare CD43+ follicular lymphomas. Am J Clin Pathol 1999;111:488–94. Thorns C, Kalies K, Fischer U, et al. Significant high expression of CD23 in follicular lymphoma of the inguinal region. Histopathology 2007;50:716–19. Barry TS, Jaffe ES, Kingma DW, et al. CD5+ follicular lymphoma: a clinicopathologic study of three cases. Am J Clin Pathol 2002;118:589–98. Tsujimoto T, Cossman J, Jaffe E, Croce C. Involvement of the bcl-2 gene in human follicular lymphoma. Science 1985;288: 1440–3. Pezzella F, Gatter KC, Mason DY. Detection of 14;18 chromosomal translocation in paraffin-embedded lymphoma tissue [letter]. Lancet 1989;i:779–80. de Jong D, Voetdijk B, van Ommen G, Kluin-Nelemans J, Beverstock G, Kluin P. Translocation t(14;18) in B cell lymphomas as a cause for defective immunoglobulin production. J Exp Med 1989;169:613. Lorsbach RB, Shay-Seymore D, Moore J, et al. Clinicopathologic analysis of follicular lymphoma occurring in children. Blood 2002;99:1959–64. Cong P, Raffeld M, Teruya-Feldstein J, Sorbara L, Pittaluga S, Jaffe ES. In situ localization of follicular lymphoma: description

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24. 25.

26.

27.

28.

29. 30.

and analysis by laser capture microdissection. Blood 2002;99: 3376–82. Pezzella F, Gatter K. What is the value of bcl-2 protein detection for histopathologists? Histopathology 1995;26:89–93. Bryant RJ, Banks PM, O’Malley DP. Ki67 staining pattern as a diagnostic tool in the evaluation of lymphoproliferative disorders. Histopathology 2006;48:505–15. The Non-Hodgkin’s Lymphoma Classification Project. A clinical evaluation of the International Lymphoma Study Group classification of non-Hodgkin’s lymphoma. Blood 1997;89: 3909–18. Martin AR, Weisenburger DD, Chan WC, et al. Prognostic value of cellular proliferation and histologic grade in follicular lymphoma. Blood 1995;85:3671–8. Relander T, Johnson NA, Farinha P, Connors JM, Sehn LH, Gascoyne RD. Prognostic factors in follicular lymphoma. J Clin Oncol 2010;28:2902–13. Solal-Celigny P, Roy P, Colombat P, et al. Follicular lymphoma international prognostic index. Blood 2004;104:1258–65. Horning SJ. Follicular lymphoma, survival, and rituximab: is it time to declare victory? J Clin Oncol 2008;26:4537–8.

13

Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is known as ‘centrocytic lymphoma’ in the Kiel classification. It was also given the name ‘intermediate lymphocytic lymphoma’ in the US literature. However, there is no evidence that the neoplastic cells derive from a germinal centre cell (as the term ‘centrocytic’ implied), and they have many of the features of mantle zone lymphocytes (although it remains to be formally proved that they derive from this cell type) [1].

Clinical features MCL accounts for about 5% of adult non-Hodgkin lymphomas in the USA and Europe. It is a tumour of older adults (median age close to 60), with a twofold excess of male : female patients. Patients usually have widespread disease at diagnosis; the sites involved are shown in Table 13.1.

Histology The pattern is usually diffuse or vaguely nodular, but welldefined follicles, resembling follicular lymphoma, are occasionally seen (Fig 13.1). In many cases the tumour involves the mantle zones of at least some reactive follicles; less commonly, a pure mantle zone pattern occurs.

The neoplastic cells are usually small to medium sized, with slightly irregular or ‘cleaved’ nuclei; however, the morphological spectrum includes lymphocyte-like and large cleaved or lymphoblast-like cells (Fig 13.2). Transformed cells (resembling ‘centroblasts’ or ‘immunoblasts’) are rare or absent. Many cases contain scattered epithelioid histiocytes, creating a ‘starry-sky’ appearance, although these cells do not contain apoptotic debris (as seen in Burkitt lymphoma). Occasionally this appearance is associated with a blastic change in mantle cell lymphoma which may occur at presentation as well as relapse (Fig 13.3). A helpful diagnostic feature pointed out by Lennert many years ago is the presence of prominent pink hyaline deposits around small capillaries in MCL (or centrocytic lymphoma as it was then) [2]. This is not specific for MCL but is useful in alerting one to think about the possibility of MCL, especially in small or needle biopsies where other architectural features may be missing or destroyed. If MCL involves the gastrointestinal tract, it is characteristically in the form of multiple small submucosal nodules, giving rise to the clinical syndrome of multiple lymphomatous polyposis. Any area of bowel can be involved although the large bowel is most common (Fig 13.4). The neoplastic cells frequently infiltrate the bone marrow either diffusely or in nodules, which may be both central or paratrabecular (Fig 13.5). When the spleen is involved the infiltration is predominantly in the white pulp and may be difficult to distinguish

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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from other low-grade B-cell lymphomas without immunophenotyping studies (Fig 13.6). Cases have been described in which the tumour is restricted to mantle zones in otherwise unremarkable lymph nodes. This has been called ‘in situ’ MCL and likened to the in situ disease seen in follicular lymphoma (Fig 13.7) [3].

Blood involvement Neoplastic cells are commonly found in the blood, although rarely in sufficient numbers to produce an overt ‘lymphoma cell leukaemia’.

Immunophenotype Table 13.1 Sites of involvement by mantle cell lymphoma. Sites

Percentage

Generalised lymphadenopathy Bone marrow positivity Splenomegaly Hepatomegaly Gastrointestinal involvement

71–90 53–93 35–81 18–35 15–28

Diffuse

Mantle zone

MCLs express the B-cell markers CD20 and CD79a in paraffin sections. They also express monotypic SIg (IgM + IgD) which is difficult to demonstrate on paraffin sections. MCLs usually coexpress CD43 and CD5 and are negative for CD23 and CD10 antigen. Exceptions and variations in all of these have been described although generally only one per aberrant case [4]. The neoplastic cells, in common with many B-cell neoplasms express bcl-2. The range of proliferation

Diffuse and nodular

Nodular

Mantle zone higher power

Fig 13.1 The different architectural patterns of mantle cell lymphoma ranging from a diffuse infiltration through to one that is predominantly nodular. Note the eosinophilic hyaline deposits around the capillaries in the diffuse lymphoma at top left, a characteristic feature of mantle cell lymphoma (MCL). A few cases have a so-called mantle zone pattern where they surround reactive germinal centres (ringed at bottom left and arrowed at higher power at bottom right).

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Aspiration cytology

Mantle Cell Lymphoma

Ultrastructure

Histological cytology Fig 13.2 The typical cytological and morphological appearances of mantle cell lymphoma. Usually no large cells of any type are present but on occasions these may be seen as shown at bottom right.

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Typical MCL

Blastic transformation

Fig 13.3 A case of typical mantle cell lymphoma (MCL) on the left which transformed into a blastic version (right) within a few months, heralding a more aggressive phase of the disease. It can be seen how easy it would be to confuse this blastic transformation with Burkitt lymphoma, on the grounds of the starry-sky appearance at low power and the blastic morphology of the cells.

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Fig 13.4 Mantle cell lymphoma (MCL) in lymphomatous polyposis of the gut is present as multiple submucosal nodules readily identified as MCL by immunostaining for cyclin D1. Note the negative endothelial cell nuclei indicating that not all are positive for cyclin D1.

H&E

CD20

CD3

Cyclin D1 on lymph node

CD20 on bone marrow

Cyclin D1 on bone marrow

Fig 13.5 A typical case of mantle cell lymphoma (MCL) presenting in the lymph node but revealing disseminated disease in the bone marrow on staging. Note the different patterns of infiltration that may be seen in bone marrow, and that cyclin D1 can be demonstrated in trephine sections as well as in lymph nodes.

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CD23

CD5

Fig 13.6 Mantle cell lymphoma (MCL) in the spleen is a white pulp infiltration similar to several other B-cell lymphomas and requires immunophenotyping for a confident diagnosis.

Cyclin D1

HE

CD5

cyclinD1

cyclinD1

Fig 13.7 Two examples of ‘in situ’ mantle cell lymphoma (MCL) restricted to the mantle zones. The upper row shows a case in a lymph node (H&E and cyclin D1) and the lower a case in the colon (CD5 and cyclin D1).

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Mantle Cell Lymphoma

H&E

bcl-2

Cyclin D1

CD5

CD3

Cyclin D1

Fig 13.8 A case of mantle cell lymphoma (MCL) showing a mantle zone pattern. The surrounded reactive germinal centres are revealed clearly by bcl-2 protein and cyclin D1 staining. CD3 immunostaining is often helpful in ensuring that the CD5+ cells are MCL rather than reactive T cells.

rates as revealed by staining for Ki-67 is relatively wide, enabling cases to be assigned to different groups for prognostic studies (Fig 13.8 and Table 13.2) [5]. A prominent, irregular meshwork of follicular dendritic cells is found even in diffuse cases (CNA.42, CD21, CD23, CD35) (Fig 13.9). The product of the cyclin D1 gene can be reliably detected in the nuclei of neoplastic mantle cells in paraffin-embedded tissue sections which is useful in distinguishing MCL from

other low-grade B-cell lymphomas [6–8]. A proportion of endothelial cell and macrophage nuclei is usually positive, providing an inbuilt control in most cases. New antibodies [9] and improvements in immunostaining machines are now producing increasing numbers of anomalous findings of cyclin D1 positivity in other lymphomas (Fig 13.10). This is usually weak and scattered, unlike the strong and frequent staining seen in MCLs, but it emphasises the need not to rely on any one parameter for a diagnosis.

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Table 13.2 The immunophenotypes of mantle cell lymphoma compared with its main differential diagnoses.

Mantle cell lymphoma Lymphoplasmacytic lymphoma Chronic lymphocytic leukaemia Follicular lymphoma Marginal zone lymphoma Splenic marginal zone lymphoma

IgM

IgD

CD5

CD10

CD23

CD43

bcl-6

Cyclin D1

+ + (+) + + +

± − (+) ± − +

+ − + − − −

− − − + − −

− ± + ± − ±

+ ± + − ± −

− − − + − −

+ − − − − −

Fig 13.9 Patterns of abnormal follicular dendritic cell meshworks seen in three different cases of mantle cell lymphoma (MCL) (CD21 left and middle; CD23 right).

Cytogenetics In most cases reciprocal translocation between chromosomes 11 and 14 juxtaposes the Ig heavy chain gene on chromosome 14 to a gene known as cyclin D1 (other names are PRAD1, bcl-1) (Fig 13.11). This encodes a cell-cycleassociated protein that is not expressed normally in lymphoid cells, and its overexpression in MCL may explain the often high mitotic index and aggressive clinical course. Many other secondary chromosomal aberrations have been reported including MYC and TP53.

Differential diagnosis Fig 13.10 Example of a follicular lymphoma in a salivary gland showing scattered weak cyclin D1 positivity in some of the centroblasts (contrast this with the strong staining seen in the salivary glands). It is important not to confuse this with the positive staining typically seen in mantle cell lymphomas and to take heed of the rest of the immunophenotype.

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MCL needs to be distinguished from other low grade B-cell lymphomas notably CLL and follicular lymphoma (Figs 13.12 and 13.13). This is best done on immunophenotyping, as described earlier with the key to MCL recognition being

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Mantle Cell Lymphoma

CCND1 BAP

Fig 13.11 Fluorescence in situ hybridisation (FISH) can used to detect the t(14;18) on paraffin sections using either fusion (left) or break-apart probes (right).

HE

bcl2

Ki67

cyclinD1

CD3

CD5

Fig 13.12 A nodular mantle cell lymphoma (MCL) that initially caused confusion with a follicular lymphoma. The MCL has expanded the mantle zone to almost engulf the residual germinal centres shown with bcl-2 and Ki67 (top row). The MCL is clearly outlined by positivity for cyclin D1 and CD5 but negativity for CD3 (bottom row).

strong clear cyclin D1 nuclear staining associated with CD5 positivity. The blastoid variant of MCL can easily be confused with lymphoblastic or Burkitt lymphoma and careful immunophenotyping will be needed to identify its true nature. Cyclin D1 is the best and most reliable marker for this purpose. Cyclin D1 has been reported to be negative in a

small number of cases of typical MCL where it is replaced by expression of either cyclin D2 or cyclin D3 [10], although great care should be taken before relying on these latter markers because they have been shown to be widely distributed in other lymphomas [11]. A recent study reports that SOX11 protein expression is positive in all MCLs, including the cyclin D1 negative cases, although it will need to be used

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HE

cyclinD1

CD3 in a panel of markers because a number of cases of lymphoblastic and Burkitt lymphoma were also positive [12]. Otherwise, a distinction from lymphoblastic lymphoma is usually made by the lack of staining for TdT (terminal deoxynucleotide transferase), CD10 and CD34. Burkitt lymphoma may be more difficult to separate if there has not been a preceding diagnosis of cyclin D1+ MCL, although lack of CD10, positivity for bcl-2 protein and a Ki67 index of <90% would indicate MCL. As a note of caution CD43 is not reliable in this differential because some typical Burkitt lym-

130

CD5

Fig 13.13 Another mimic of follicular lymphoma is a mantle cell lymphoma (MCL) that colonises germinal centres. Here the MCL is shown replacing the germinal centre as cyclin D1+, CD5+ B cells. The mantle zones are reactive.

phomas, as well as lymphoblastic B-cell lymphomas, are positive for this marker. Transformation to a large-cell lymphoma composed of centroblasts and/or immunoblast-like cells does not appear to occur, although a gradual increase in the size of the tumour cells accompanied by an increase in proliferation fraction often occurs at relapse. This more aggressive type is also known as the pleomorphic variant. These two variants are often lumped together as blastoid/pleomorphic mantle cell lymphoma (Fig 13.14).

Fig 13.14 The case illustrated here was an elderly man who presented with a lymphocytosis consistent with chronic lymphocytic leukaemia (CLL). (a) Bone marrow presentation – CLL like; (b) splenic relapse with blastic transformation. The bone marrow trephine morphology and proliferation index were interpreted as supportive of that diagnosis. However, he was refractory to CLL therapy and indeed high-grade non-Hodgkin lymphoma (NHL) therapy when instituted, and deteriorated remorselessly. He developed a high-grade lymphoma in the spleen that was shown to be a blastoid/pleomorphic transformation of mantle cell lymphoma (MCL). Interestingly, the areas of blast cells are surrounded by areas of ‘low-grade’ disease, which is also cyclin D1+. Retrospectively the original bone marrow specimen was shown to be cyclin D1+, emphasising the importance of thinking about MCL in the initial diagnosis of low-grade B-cell lymphomas.

Proliferation (a) Bone marrow presentation: CLL-like

Cyclin D1

Low power H&E

High power H&E

CD20

CD5

Cyclin D1 (b) Splenic relapse with blastic transformation

Proliferation

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Mantle Cell Lymphoma

Before treatment: CD20 immunostain

After treatment: CD20 immunostain

After treatment: CD79a immunostain Fig 13.15 Anti-CD20 antibody therapy (rituximab) has a dramatic effect on bone marrow infiltrates as shown in this case of mantle cell lymphoma (MCL). Normal marrow B cells recover because a population of precursor cells and plasma cells remains as highlighted by CD79a immunostaining.

Prognosis and treatment The course is moderately aggressive [13]. The median survival ranges from 3 years to 5 years; the blastoid/pleomorphic variant is reported in some studies to be more aggressive, with a median survival of 3 years. The proliferation rate is proving to be one of the most accurate prognostic factors [4]. The response rate to conventional chemotherapy is better than 80% and about half of all patients achieve complete remission. The median progression-free survival is 20 months and the median overall survival is 36 months. There is no evidence that any conventional chemotherapy regimen is curative. Patients with slowly progressive disease might be managed with chlorambucil, cyclophosphamide

132

or CVP (cisplatin–vinblastine–dacarbazine). Markedly symptomatic patients or rapidly progressive cases should probably be treated with CHOP (cyclophosphamide– hydroxydaunorubicin–vincristine [Oncovin]–prednisone). Trials with anti-CD20 (rituximab) and biologic agents such as Velcade have had encouraging results, although treatment of MCL remains a challenge (Fig 13.15) [14,15].

References 1. Banks P, Chan J, Cleary M, et al. Mantle cell lymphoma: a proposal for unification of morphologic, immunologic, and molecular data. Am J Surg Pathol 1992;16:637–40. 2. Lennert K, Feller A. Histopathology of Non-Hodgkin’s Lymphomas, 2nd edn. New York: Springer-Verlag, 1992.

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3. Richard P, Vassallo J, Valmary S, Missoury R, Delsol G, Brousset P. ‘In situ-like’ mantle cell lymphoma: a report of two cases. J Clin Pathol 2006;59:995–6. 4. Gao J, Peterson L, Nelson B, Goolsby C, Chen YH. Immunophenotypic variations in mantle cell lymphoma. Am J Clin Pathol 2009;132:699–706. 5. Determann O, Hoster E, Ott G, et al. Ki-67 predicts outcome in advanced-stage mantle cell lymphoma patients treated with anti-CD20 immunochemotherapy: results from randomized trials of the European MCL Network and the German Low Grade Lymphoma Study Group. Blood 2008;111:2385–7. 6. Bosch F, Jares P, Campo E, et al. PRAD-1/cyclin D1 gene overexpression in chronic lymphoproliferative disorders: a highly specific marker of mantle cell lymphoma. Blood 1994;84: 2726–32. 7. de Boer CJ, van Krieken JH, Schuuring E, Kluin PM. Bcl-1/ cyclin D1 in malignant lymphoma. Ann Oncol 1997;8(suppl 2):109–17. 8. Campo E, Raffeld M, Jaffe ES. Mantle-cell lymphoma. Semin Hematol 1999;36:115–27. 9. Cheuk W, Wong KO, Wong CS, Chan JK. Consistent immunostaining for cyclin D1 can be achieved on a routine basis using

10.

11.

12.

13.

14. 15.

Mantle Cell Lymphoma

a newly available rabbit monoclonal antibody. Am J Surg Pathol 2004;28:801–7. Fu K, Weisenburger DD, Greiner TC, et al. Cyclin D1-negative mantle cell lymphoma: a clinicopathologic study based on gene expression profiling. Blood 2005;106:4315–21. Metcalf RA, Zhao S, Anderson MW, et al. Characterization of D-cyclin proteins in hematolymphoid neoplasms: lack of specificity of cyclin-D2 and D3 expression in lymphoma subtypes. Mod Pathol 2010;23:420–33. Mozos A, Royo C, Hartmann E, et al. SOX11 expression is highly specific for mantle cell lymphoma and identifies the cyclin D1-negative subtype. Haematologica 2009;94:1555–62. A clinical evaluation of the International Lymphoma Study Group classification of non-Hodgkin’s lymphoma. The NonHodgkin’s Lymphoma Classification Project. Blood 1997;89: 3909–18. Zelenetz AD. Mantle cell lymphoma: an update on management. Ann Oncol 2006;17(suppl 4):iv12–4. Ruan J, Coleman M, Leonard JP. Management of relapsed mantle cell lymphoma: still a treatment challenge. Oncology 2009;23:683–90.

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14

Diffuse Large B-cell Lymphoma

The REAL classification created the category of ‘diffuse large B-cell lymphoma’ (DLBCL). It includes the categories of ‘diffuse large cell (cleaved or non-cleaved)’ and ‘immunoblastic’ lymphoma from the working formulation and ‘centroblastic’ (diffuse) and ‘immunoblastic (B-cell type)’ lymphoma in the Kiel classification. In doing this it was recognised that the category probably comprised more than one clinically relevant subtype, but at that time it was felt there were no criteria that allowed reproducible subdivision [1]. This was considered to be particularly true of the morphological subdivision of large B-cell lymphomas which had been consistently shown to be both poorly reproducible in practice and lacking in prognostic discrimination. This was not accepted by the Kiel group which felt that the subdivision could be made with adequate sections and training, and was very relevant to clinical outcome [2]. The World health Organization (WHO) classification has compromised between these two views by accepting the overall REAL viewpoint for a single entity, but gives the criteria necessary to allow subdivision if individual pathologists feel confident to do this [3]. This has been further developed into a number of variants and subtypes in the 2008 WHO classification [3] as detailed in Table 14.1.

Clinical features Large-cell lymphomas mostly occur in elderly people although they are not restricted to any age group. Usually patients present with rapidly growing lymph nodes or extranodal masses often confined to one area.

Histology Normal tissue architecture is usually replaced by a diffuse infiltrate of large lymphoid cells. Occasionally a dispersed

growth pattern is seen in which the neoplastic cells are intimately intermingled with normal tissue constituents. Infiltration of soft tissue outside the lymph node is common. In extranodal sites the lymphoma usually exhibits permeative growth at the edges and invasion of blood vessel walls is common. When a lymph node is not totally replaced by neoplastic cells, there may be selective involvement of sinusoidal or interfollicular areas. At times, the lymphoma forms discrete nodules, but these differ from follicular lymphoma in that they are focal and often of a large size. Furthermore the cytological composition does not correspond to that of follicle centre cells and meshworks of follicular dendritic cells are not present. Cell morphology and nuclear appearances are highly variable from case to case (Fig 14.1). The neoplastic cells are typically large, with nuclei larger than those of reactive histiocytes. A rule of thumb often given is that in paraffin sections a large cell is twice the size of a reactive lymphocyte. In practice one has to be more flexible as lymphocytes are not actually all one size and large cells are remarkably pleomorphic. Indeed occasionally the neoplastic cells are medium sized, but they differ in their nuclear or cytoplasmic features from the most common medium-sized cell lymphomas, namely lymphoblastic and Burkitt lymphoma. Nucleoli are almost invariably conspicuous; they may be multiple or solitary. Highly bizarre cells or multinucleated forms occur which may mimic Reed–Sternberg cells. The cytoplasm varies in quantity and in staining properties. Mitotic figures, including atypical forms, are easily identified. The WHO classification recognises three main morphological variants: centroblastic (with or without multilobated nuclei), immunoblastic (with >90% immunoblasts) and anaplastic (with very large pleomorphic cells). There are several other rare variants, some of which appear now as separate subtypes. This tremendous variety of cytology and histology is a further reflection of the view that this lym-

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Table 14.1 Diffuse large B-cell lymphoma: variants, subgroups and subtypes/entities. Diffuse large B-cell lymphoma, not otherwise specified (NOS) Common morphological variants Centroblastic Immunoblastic Anaplastic Rare morphologic variants Molecular subgroups Germinal-centre, B-cell-like (GCB) Activated B-cell-like (ABC) Immunohistochemical subgroups CD5-positive DLBCL Germinal-centre B-cell-like (GCB) Non-germinal centre B-cell-like (non-GCB) Diffuse large B-cell lymphoma subtypes T-cell/histiocyte-rich, large B-cell lymphoma Primary DLBCL of the CNS Primary cutaneous DLBCL, leg type Epstein–Barr virus positive DLBCL of elderly people Other lymphomas of large B cells Primary mediastinal (thymic) large B-cell lymphoma Intravascular large B-cell lymphoma DLBCL associated with chronic inflammation Lymphomatoid granulomatosis ALK-positive DLBCL Plasmablastic lymphoma Lymphoma arising in HHV8-associated multicentric Castleman disease Primary effusion lymphoma Borderline cases B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and classic Hodgkin lymphoma

phoma type is really several different as yet incompletely recognisable entities. It is worth commenting on the anaplastic variant of large B-cell lymphoma because this continues to cause diagnostic problems (Fig 14.2). This type is characterised by very large round, oval, or polygonal cells with bizarre pleomorphic nuclei which may resemble Reed–Sternberg cells. The cells may grow in a cohesive pattern mimicking carcinoma and show a striking sinusoidal pattern of growth. Many cases are positive for CD30 so that this tumour was originally considered as part of the spectrum of anaplastic large cell lymphoma (ALCL). The available evidence is now against this because these cases do not possess the t(2;5) characteristic of ‘true’ ALCL and are negative for ALK (anaplastic lymphoma kinase) staining [4]. Some cases of diffuse large B-cell lymphoma with an anaplastic morphology may be rich in Reed–Sternberg-like

Diffuse Large B-cell Lymphoma

cells and thus simulate lymphocyte depleted classic Hodgkin lymphoma. However, in contrast to Hodgkin lymphoma, these neoplastic cells are uniformly positive for both CD20 and CD79a antigens and are negative for CD15. Reactive cells in the background are also variable, some cases being rich in smaller T lymphocytes, histiocytes or eosinophils. The infiltrate may be monomorphous or exhibit considerable variation in the size of the tumour cells. Rarely neoplastic (monotypic) plasma cells expressing the same immunoglobulin light chain as the neoplastic large B cells are present.

Immunophenotype The majority (65–85%) of diffuse large-cell lymphomas are of B-cell type. Diffuse large B-cell lymphomas express pan-B markers, e.g. CD19, CD20, CD22, CD75 and CD79a, but there may be an ‘aberrant’ lack of staining with one or more of these, especially in diffuse large B-cell lymphomas expressing the ALK protein (CD20−, CD79a−, IgA+) (Table 14.2 and Fig 14.3). Surface and/or cytoplasmic immunoglobulin (usually IgM) can be demonstrated in 50–75% of cases. Cytoplasmic immunoglobulin is more commonly demonstrated in cases exhibiting plasmacytoid differentiation. About 10% express CD5 and 30% CD10. The gene bcl-6 is expressed in approximately 80% of cases and is independent of bcl-6 rearrangement. Coexpression of CD10 and bcl-6 is considered to be a marker of a diffuse large B-cell lymphoma arising from follicle centres [5]. Most diffuse large B-cell lymphomas are HLA-DR+. Approximately 10% of diffuse large B-cell lymphomas, particularly those with anaplastic morphology, express CD30 and EMA (epithelial membrane antigen). These tumours are, however, negative for ALK protein and in the REAL and WHO classifications are just considered as morphological variants of diffuse large B-cell lymphomas. The proliferating fraction, as detected by Ki67 staining, is usually high (more than 40% of neoplastic cells). The bcl-2 protein is expressed in twothirds of cases. A proportion of diffuse large B-cell lymphomas are associated with Epstein–Barr virus (EBV). Latent infection of malignant cells by EBV can be demonstrated by LMP (latent membrane protein) immunostaining or EBV-encoded RNA (EBER) in situ hybridization. About 10% of primary tumours occurring in immunocompetent mostly elderly patients are EBV positive. These are now considered to be a separate clinical subentity in patients aged over 50 years. By contrast most of such tumours in patients with immunodeficiencies are EBV positive. Similarly a significant number of large B-cell lymphomas secondary to low-grade lymphoma are associated with EBV. Diffuse large B-cell lymphoma frequently has extensive areas of necrosis but even here good immunostaining can lead to the correct diagnosis (Fig 14.4).

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Diffuse Large B-cell Lymphoma

Centroblastic

Immunoblastic

Predominantly centroblastic

Predominantly immunoblastic

Unclassifiable

Polylobated

Fig 14.1 The morphological range of diffuse large B-cell lymphoma is wide. The top two images show the classic types of centroblastic and immunoblastic whereas the lower four show examples of how the morphology can vary from this.

Cytogenetics Rearrangement of the bcl-2 gene, due to the t(14;18) translocation (the hallmark of follicular lymphoma) occurs in 20–30% of diffuse large B-cell lymphoma, suggesting a relationship to follicular lymphoma in these cases [6,7]. Up to 30% of diffuse large-cell lymphomas show a reciprocal chromosomal translocation involving the 3q27 region [8]. This is the site of the bcl-6/LAZ3 genes that encode a zinc finger transcription factor. The bcl-6 rearrangement is more frequent (approximately a third of cases), indicating that ‘cryptic’ cytogenetic anomalies are present [9,10]. The presence of bcl-6 rearrangement in diffuse large-cell lymphoma

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correlates strongly with extranodal involvement. The bcl-6 and bcl-2 rearrangements are almost mutually exclusive in diffuse large-cell lymphomas. Approximately 10–20% of diffuse large-cell lymphomas show translocation of the oncogene c-myc and a similar proportion show inactivation of the Rb gene.

Differential diagnosis Anaplastic tumours of non-lymphoid origin In general diagnostic practice the most common differential diagnosis is not with other lymphoma entities but with anaplastic tumours of non-lymphoid origin especially car-

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Diffuse Large B-cell Lymphoma

CD20

CD30

CD20

proliferation (Ki67)

Fig 14.2 This case shows the typical architecture and cytology of anaplastic large cell lymphoma. Although the cells are CD30+ they are ALK (anaplastic lymphoma kinase) protein negative and do not show evidence of t(2;5). These tumours are best regarded at present as a variant of large B-cell lymphoma.

Table 14.2 The immunophenotypes of diffuse large B-cell lymphoma compared with its main differential diagnoses.

Diffuse large B Burkitt lymphoma Blastic mantle cell lymphoma B Lymphoblastic Blastic myeloma

CD20

CD79a

CD5

CD10

CD23

Ki67 (%)

TdT

bcl-2

Cyclin D1

+ + + ± −

+ + + + +

± − + − −

± + − + −

− − − − −

<90 >95 <90 <90 <90

− − − + −

± − ± ± ±

− − + − ±

cinoma and melanoma (Fig 14.5). Positivity for the leukocyte common antigen (CD45 molecule) is very useful for excluding carcinoma, except that about 10% of large Bcell lymphomas do not express it. Furthermore occasional cases of large B-cell lymphomas express cytokeratins, although with an unusual dot-like staining restricted to the paranuclear area. For these reasons it is important when considering this differential to include B- (and T)-cell markers as well. Other so-called ‘aberrant’ antigens have been described such as S100 protein, actin and vimentin. None of these is

actually lineage specific and fortunately is rarely problematic in routine practice.

Histiocytic sarcoma This may simulate diffuse large B-cell lymphoma but the neoplastic cells lack B-cell markers and express histiocytic antigens, notably CD68 (antibodies KP1 and PGM1).

Reactive lymphoproliferation This is seen when infectious mononucleosis is rich in immunoblasts and may be misdiagnosed as a diffuse large B-cell

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CD20

CD79a

CD20

CD79a

bcl2

mib1

Fig 14.3 The typical immunophenotype of diffuse large B-cell lymphoma is CD20 (upper left × 2) and CD79a (upper right × 2) positive. Note how robust these two markers are in highlighting the necrotic areas to the left of each low power field. Typically these tumours are also bcl-2+ (lower left) with a high proliferation rate of more than 30% (mib1 – lower right).

lymphoma. A clue to its identity is that the lymph node architecture is usually not totally effaced and the large cell population consists of a mixture of B cells and T cells (often CD8+). In infectious mononucleosis the large B cells are a mixture of κ- and λ-labelled cells. Many of these large cells show evidence of EBV infection (LMP+, EBER+). Occasional cases of Kikuchi necrotising lymphadenitis may also resemble diffuse large B-cell lymphomas but most of the blast-like cells are in fact of monocytic origin, with the remainder being reactive T cells that may be large and mainly CD8+. In fact distinction from T-cell lymphoma can be challenging although the clinical presentation of Kikuchi disease is often helpful, i.e. young age and localised disease (Fig 14.6).

Prognosis and treatment A number of features are of value in predicting overall survival and relapse-free survival. These include age, lactate

138

dehydrogenase (LDH), performance status, stage of disease and number of extranodal disease sites. An individual patient’s relative risk for death can be determined by adding the number of adverse prognostic factors present at diagnosis, and patients can be divided into low- and high-risk groups. Large-cell lymphoma is an aggressive disease but long-term survivors do seem to be cured. Treatment currently is the subject of many clinical trials. A major advance was achieved with the introduction of the CHOP (cyclophosphamide – hydroxydaunorubicin – Oncovin [vincristine]–prednisone) regimen more than 30 years ago, which has not yet been superseded by any other currently available drug schedule apart from the addition of rituximab to CHOP itself [11]. Given the considerable heterogeneity of DLBCLs there is an extensive literature documenting the hunt for prognostic markers to separate DLBCLs with a favourable outcome from the more aggressive tumours. To date, none has really stood the test of time or been able to guide therapy. Leading immunocytochemical contenders have been bcl-2 (bad) and

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Diffuse Large B-cell Lymphoma

Fig 14.4 A necrotic large B-cell lymphoma revealed by immunostaining. Many antigens are remarkably resistant to degradation, CD20 and CD79a being two examples. Immunostaining can therefore be crucial in identifying lymphoma in situations such as that where the biopsy is totally necrotic.

H&E

CD20

bcl-6 (good) protein expression but both seem to have been wiped out by the addition of rituximab to the CHOP regimen [12]. Proliferation rate and EBV status are still being considered although there are insufficient data yet to substantiate either as definitive. Perhaps the most interesting new advance in large B-cell lymphoma subtyping for clinical purposes has come from gene expression studies using DNA microarray technology [13]. This has identified two distinct classes of large B-cell lymphoma as germinal centre-derived (GC type) and activated (ABC type) with different clinical outcomes. This genetic approach is still not applicable to routine clinical practice so attempts have been made to mimic it with antibodies. The most widely known is the so-called ‘Hans classifier’ where a combination of CD10, bcl-6 and MUM1 are used to sort DLBCLs into two groups, ostensibly of GC and ABC subtypes with appropriate clinical behaviour [14] (Fig 14.7). A more recent study dropping MUM1 and substituting bcl-2 and cyclin D2 has claimed a better risk stratification than Hans [15]. Unfortunately all of these studies suffer from relatively small numbers of cases mainly from the prerituximab era, and so far available confirmatory studies are somewhat contradictory. However, this is an area of clear importance and has been taken up by major lymphoma trial groups, so one can hope that a definitive answer will emerge in the near future. Related to this is the current finding that the NF-κB pathway is activated in many large-cell lymphomas, especially those of the ABC type. This can be identified immunohistochemically with a potential benefit to patients from targeted anti-NF-κB therapeutic approaches [16]. An early inkling of this comes from a recent small study of cases of relapsed or refractory DLBCL treated with bortezomib, a known NF-κB inhibitor, combined with chemotherapy. In those patients with ABC-type tumours (where NF-κB activation is much commoner) the response was significantly higher than in those with GC type [17].

Diffuse large B-cell lymphoma subtypes T-cell/histiocyte-rich B-cell lymphoma

CD79a

This is defined as a diffuse proliferation with many pleomorphic large B cells scattered singly or in small clusters in a sea of reactive T cells with variable numbers of histiocytes. These latter often cluster around the large abnormal B cells that may be helpful in the diagnosis of this subtype [18]. Small B cells are infrequent and certainly not present in nodules

139

HE

HE

Cytokeratin

CD20 Fig 14.5 This case was initially diagnosed as carcinoma on morphology (top left and middle) but clinical doubt led to immunostaining showing negativity for cytokeratins (top right) and positivity for CD20 (bottom). This was a diffuse large B-cell lymphoma-stimulating carcinoma.

Histology

CD20

Proliferation

Fig 14.6 Focal involvement of lymph node by large B-cell lymphoma. Immunostaining reveals a focal area of large cell lymphoma that had been initially misinterpreted as necrotising lymphadenitis. Staging procedures demonstrated more widespread lymphoma.

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DLBCL CD10+ GC subtype

CD10–

Diffuse Large B-cell Lymphoma

The previously poor prognosis of this entity has been considerably improved by new chemotherapy regimens that include methotrexate [19] (Fig 14.9).

Primary cutaneous DLBCL, leg type Bcl6+

MUM1– GC subtype

bcl6– Non-GC subtype

MUM1+ Non-GC subtype

Fig 14.7. The HANS classifier scheme for diffuse large B-cell lymphoma (DLBCL).

or clumps. It remains a somewhat controversial category of large B cell lymphoma since the definition given above is not very precise and at times it can be difficult to distinguish it from nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) when that condition is a little less obviously nodular than one would like for diagnostic purposes. In these cases the immunophenotype of the B cells is similar to that of NLPHL with many of the large cells being positive for EMA but negative for CD30. The distinction from NLPHL is usually confirmed on clinical grounds with the large B cell lymphoma being commoner in elderly patients and presenting as disseminated disease with a more aggressive course than NLPHL. From time to time cases with all of these features but without macrophages are seen. Some of these will be EBV positive that typical T-cell/histiocyte-rich B-cell lymphoma (THRLBCL) is not and should be classified with the EBV positive DLBCLs. The others should be classified with THRLBCL but noted as requiring further study. Finally it needs to be realized that many B cell lymphomas are relatively rich in T cells so any case with a definite population of small B cells whether diffuse or clustered should not be included in this category (Fig 14.8).

Primary DLBCL of the central nervous system These are clinically quite distinct large B-cell lymphomas, provided that other potentially confusing cerebral lymphomas such as intravascular lymphoma or cerebral involvement by any systemic lymphoma have been excluded. The 2008 World Health Organization (WHO) classification also specifically excludes those associated with any immunodeficiency, which needs to be borne in mind if reading the clinical literature where HIV+ cases are often the predominant primary cerebral lymphomas in their series. Otherwise these tumours have, similarly to other DLBCLs, a variable morphological picture. They are often associated with extensive areas of necrosis and EBV is usually absent.

These are primary cutaneous lymphomas comprised almost exclusively of large B cells which usually arise on the legs of elderly patients. In spite of all the ribaldry from pathologists, the dermatologists have clearly shown that these tumours have a much worse prognosis than the other common primary B-cell lymphomas of the skin [20]. In our view this is because these are diffuse large B-cell lymphomas that happen predominantly to arise on the leg, whereas all the other primary B-cell lymphomas of the skin are lowgrade B-cell lymphomas. Confusion generally arises with the diffuse primary cutaneous follicle centre lymphomas which can at times have more large cells than expected though they never have the sheets of large cells seen in the leg-type lesions. If they do then they should be classified as this entity, i.e. primary cutaneous DLBCL, leg type, and indeed about 20% of cases do arise in sites other than the legs (Fig 14.10).

EBV-positive DLBCL of elderly people This category consists of DLBCLs occurring in elderly patients (defined as those aged >50 years) that are EBV positive without known immunodeficiency or prior lymphoma. Such cases are best documented for Asian patients, in whom they account for about 10% of cases and have been categorised separately due to their clearly worse clinical course and prognosis [21,22]. Morphologically there is nothing specific to distinguish these from other cases of DLBCL, although they present more commonly with extranodal disease than EBV-negative patients. The EBV is usually detected by EBER in situ hybridization, although most cases are also positive for LMP-1 by immunocytochemistry. Similar numbers of cases are seen in western countries though as yet there are insufficient clinical data to confirm that they behave in the same poorer fashion [23]. It is hoped that this new subcategorisation will identify many more cases to ratify the clinical identity of this new entity (Fig 14.11).

DLBCL associated with chronic inflammation These are DLBCLs that arise in the setting of severe chronic inflammation, most notably that associated with longstanding pyothorax, but this phenomenon is also seen with osteomyelitis, assorted metal implants and chronic venous ulcers. They may have an aberrant phenotype expressing both B (CD19, CD20) and T-cell (CD2, CD3, CD4, CD43)-associated antigens which can cause diagnostic confusion [24]. Virtually all cases are EBV positive and, similar to EBV-positive DLBCL, have an aggressive course with poor survival.

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Diffuse Large B-cell Lymphoma

Histology

CD20

CD20

CD3

CD3

CD68

CD68

EMA

mib1

Fig 14.8 The T-cell/histiocyte-rich variant of diffuse large B-cell lymphoma shows a diffuse pattern of infiltration with numerous scattered separated large pleomorphic cells (top row left and right). These large cells are CD20+ B cells with very few small B cells. They are embedded in a matrix rich in T cells CD3 and histiocytes CD68. EMA is frequently positive and most are proliferating (mib1).

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HE

CD20

HE

CD20

mib1

CD10

Fig 14.9 Primary lymphomas of the central nervous system frequently have a perivascular localisation especially on the HEs, whereas more diffuse spread is usually apparent on CD20 staining. The proliferation rate is high mib1 and they are typically CD10 negative.

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Lymphomatoid granulomatosis Although this angiocentric lymphoma, which often presents as a necrotic pulmonary mass, was thought to represent a reactive lesion or peripheral T-cell lymphoma in the past, recent studies have identified this as a variant of DLBCL. The rare neoplastic large cells, typically located around vessels (angiocentric and angiodestructive), express B-cell antigens, contain EBV and are associated with a heavy nonneoplastic infiltrate of T cells and/or macrophages. A threestage histological grading system is based on the number of large EBV-positive B cells. Grade 3, composed of large abnormal EBV-positive cells, is the most obvious DLBCL subtype and also the most aggressive. The other two grades, especially grade 1, in which the EBV-positive cells are small and few in number, are difficult to diagnose and probably best left to experts in this condition because they are treated with interferon instead of chemotherapy in the first instance. Historically this disease has had a poor prognosis but the identification of its nature as a DLBCL subtype with the introduction of rituximab-enhanced chemotherapy has started to show much better results [25] (Fig 14.12).

Other lymphomas of large B-cells Primary mediastinal (thymic) large B-cell lymphoma

HE

CD20

CD79a

mib1

Fig 14.10 Primary cutaneous diffuse large B-cell lymphoma (DLBCL), leg type often presents with large solitary raised red nodules, frequently in areas of venous stasis (upper picture left). These tend to coalesce and ulcerate with time (upper picture right). The tumours are diffuse monomorphic infiltrates HE composed of CD20+ and CD79a+ B cells with a high mib1+ proliferation rate. (Clinical pictures courtesy of Professor L Cerroni.) 144

Mediastinal large B-cell lymphoma is a diffuse large-cell lymphoma presenting primarily with anterior mediastinal involvement. An origin in the thymus gland can be demonstrated in at least a proportion of cases. Although some mediastinal large B-cell lymphomas may be cytologically indistinguishable from large-cell lymphomas of other sites, they merit separate consideration because of their distinct clinicopathological features [26,27]. This is primarily a disease of young adults, especially females. It generally presents with localised mediastinal disease which may include superior vena cava obstruction. If the tumour relapses outside the mediastinum, it tends to be extranodal in sites such as lung, liver, gut and brain. Spread to lymph nodes or bone marrow is infrequent. Mediastinal large B-cell lymphoma exhibits a diffuse infiltrative growth, permeating the soft tissues of the anterior mediastinum. In rare cases, the tumour is confined predominantly to the medulla of the thymus. Sclerosis is often prominent, taking the form of hyaline twigs that compartmentalise the tumour cells into alveolar clusters and cords, delicate interstitial fibrils intimately interspersed among tumour cells and broad sclerotic bands. The neoplastic cells possess medium-sized to large nuclei which can be round, oval, irregularly folded, elongated, multilobated or multinucleated. The chromatin is vesicular or granular, and single or multiple distinct nucleoli are often observed. The cells may appear uniform or show significant pleomorphism. Binucleate Reed–Sternberg-like cells are not

CHAPTER 14

HE

Diffuse Large B-cell Lymphoma

CD20

EBER in situ

Fig 14.11 Epstein–Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) of elderly people are morphologically typical DLBCLs (left), which are CD20+ and rich in EBER + EBV-infected cells.

uncommon. Frequently, there is a moderate or abundant amount of pale to clear cytoplasm. However, the cytoplasmic clearing appears to be an artefact of formalin fixation, because it is usually not evident in tissues fixed in B5 or Zenker’s fixative. In other cases, the cytoplasm is amphophilic and less abundant, and the cells are cytologically indistinguishable from those of other diffuse large B-cell neoplasms. There may be islands of residual thymic epithelium interspersed throughout the tumour or scattered at the periphery that may undergo hyperplasia, forming irregular anastomosing strands or epithelium-lined cystic spaces, which may also be infiltrated by lymphoma cells. These can be usefully highlighted by cytokeratin immunostaining. Mediastinal large B-cell lymphomas are postulated to arise from the thymic B cells normally residing in the medulla, which are apparently unrelated to follicle centre cells and mantle cells. The immunophenotypic profile includes most pan-B-cell markers (CD20 and CD79a for paraffin sections) but differs somewhat from other large B-cell lymphomas in that they usually do not express immunoglobulins, CD5 or CD10. In many cases a significant number of tumour cells express CD30 and/or CD23 (Fig 14.13). Amplifications involving chromosomes 2p, 9p, 12p and the REL gene have been reported in some cases and, as these changes do not occur in other large-cell lymphomas, this supports the concept that mediastinal lymphoma is a separate disease entity. This is further supported by the fact that MAL gene expression by large-cell lymphomas is predominantly seen in mediastinal B-cell lymphomas [28].

Differential diagnosis As a result of this tumour’s location small needle biopsies are commonly taken. On these biopsies mediastinal B-cell lymphomas may be difficult to distinguish from thymoma or nodular sclerosing Hodgkin lymphoma. Immunostaining usually assists greatly because most thymomas have a diffuse cytokeratin meshwork and are infiltrated by terminal deoxynucleotidyl transferase (TdT)-positive T lymphocytes with few B cells. Hodgkin lymphoma is CD15+ as well as CD30+ and usually has limited expression of CD20 and little or none for CD79a.

Prognosis and treatment Initially this tumour was described separately in view of its aggressive nature. Study of more cases has shown that the course is similar to other large-cell lymphomas with a proportion of patients achieving long-term survival.

Intravascular large B-cell lymphoma This subtype of large B-cell lymphoma is rare and may present with symptoms in any organ, although the skin and brain are perhaps the most common. In the past its identification as a lymphoma was not clear, so the condition has had a number of synonyms including angioendotheliomatosis proliferans systemisata, malignant angioendotheliomatosis, intravascular lymphomatosis and angiotropic lymphoma. The lymphoma is composed of a disseminated intravascular proliferation of large B cells (CD20+ and CD79a+) with vesicular chromatin, prominent nucleoli and numerous mitotic figures. Malignant cells are rarely seen in

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CD20

CD30

EBV

Fig 14.12 Case of lymphomatoid granulomatosis in the lung showing the typical polymorphous infiltrate in pulmonary vessels composed of scattered large B cells (the rest of the lymphocytes are mainly T cells – not shown). Some of these B cells are CD30+ and in a proportion Epstein–Barr virus latent membrane protein can be demonstrated immunocytochemically.

cerebrospinal fluid, blood or lymph node. A small number of cases of T-cell phenotype (CD3 positive) have been described. This condition is usually quite resistant to therapy and survival is short [29], although recent experience with rituximab-based chemotherapy looks promising [30,31], especially in the slightly better prognostic category of cutaneous intravascular lymphomas (Fig 14.14).

ALK-positive diffuse large B-cell lymphoma Large B-cell lymphomas expressing ALK show a sinusoidal growth pattern and consist of monomorphic large immunoblast-like cells, containing large central nucleoli [32]. Superficially they resemble anaplastic large-cell lymphomas, even expressing EMA, but crucially they lack CD30. They contain intracytoplasmic IgA of a single light chain type and express plasma cell-associated markers such as CD138 and VS38. They lack lineage-associated leukocyte antigens

146

(CD3, CD20, CD79a) with the exception of CD4 and CD57. These tumours express weakly or are even negative for the leukocyte common antigen CD45. They express the fulllength form of the ALK protein and are labelled by the antiALK antibodies ALK1 and ALK-EC, detecting both the intracytoplasmic and extracellular regions of the ALK receptor kinase. Typically this has the distinctive granular cytoplasmic localisation of the CLTC–ALK fusion protein indicating a t(2;17) translocation, although the other ALK-related translocations as seen in ALCL can occur. Most patients are men and the disease follows an aggressive course [33]. Importantly, if one is unaware of this lymphoma and fail to perform Ig staining or polymerase chain reaction for gene rearrangement, it is easy to misdiagnose this lymphoma as a metastatic malignancy because of its negativity for the commonly used lymphoma markers such as CD45, CD20 and CD3 (Fig 14.15).

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Diffuse Large B-cell Lymphoma

CD20

Fig 14.13 Primary mediastinal (thymic) large B-cell lymphoma has a typical sclerosed low power picture (top row left) with many large tumour cells possessing a clear cell appearance due to their abundant cytoplasm (top right). They are CD20+ B cells, most of which are also CD79a+. CD30 is present on a minority of these large cells which have a high mib1+ proliferation rate and are usually MUM1+.

CD30

Plasmablastic lymphoma This is a rare large-cell lymphoma that typically presents in the oral cavity in the setting of HIV infection but does occur at other sites in HIV-negative patients [34]. 60% of cases express EBV antigens but are human herpesvirus 8 (HHV8) negative. The immunoblast-like cells are usually negative for CD20 and CD45 but express plasma cell markers such as CD138 and p63 protein (VS38) indicating their plasmablastic nature. These lymphomas are distinct clinically from myeloma and generally pursue an aggressive course, although there is evidence of better survival if any underlying HIV can be controlled [35].

Large B-cell lymphoma arising in HHV8associated multicentric Castleman disease This is very similar in morphology and immunophenotype to the plasmablastic lymphoma but arises in association with multicentric Castleman disease with the coexpression of

CD79a

mib1

MUM1

HHV8, usually in the setting of HIV infection. Typically these tumours are EBV negative [36] though increasingly reports of positivity are appearing [37] (Fig 14.16).

Primary effusion lymphomas Primary effusion lymphoma (PEL) was first recognised in HIV-positive patients with AIDS and is still virtually restricted to this group. It presents as serous effusions in body cavities with little or no evidence of tissue infiltration. Rare HHV8+ lymphomas indistinguishable from PEL do present in a variety of extranodal sites such as the gut or skin. These have been termed the ‘extracavity variant of PEL’ [38]. The disease is associated with two herpesviruses, EBV and HHV8, and often coexists with Kaposi sarcoma. The tumour cells are large often with an immunoblastic or anaplastic cytology. Immunostaining reveals a plasma cell phenotype (CD20− but CD79a± with p63, CD38 and CD138

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H&E

CD45

CD79a

positivity) suggesting a possible origin from these. CD30 and EMA are also usually expressed. The clinical course is relentlessly progressive regardless of therapy and most patients die in less than 6 months, sometimes as much from the coexisting AIDS or Kaposi sarcoma as from the lymphoma [39,40].

Borderline cases B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt lymphoma This is a difficult category to use which is well reflected by its description in the WHO handbook: ‘This is a heterogeneous category that is not considered a distinct disease entity, but is useful in allowing the classification of cases not meeting criteria for classical BL or DLBCL.’ It mostly seems to be used for those cases that are morphologically not right

148

Factor VIIIRA

Fig 14.14 Intravascular large B-cell lymphoma is largely confined to smaller blood vessels in tissues such as the skin shown here. This localisation can be higlighted by vascular stains such as factor VIII-related antigen (shown here) or CD31 or CD34.

for Burkitt lymphoma (too many big cells, too polymorphic) but in which the immunophenotype is spot on (B cell, CD10+ bcl-2− bcl6+ Ki67 >95%). Other cases that lodge here could be those with a perfect Burkitt lymphoma morphology but the immunophenotype is odd, e.g. bcl-2+ or TdT+. Genetically many of these borderline cases have myc translocations to non-immunoglobulin genes often in association with other translocations, especially those involving bcl-2. Molecular profiling studies have shown characteristic and distinctive gene signatures for typical Burkitt lymphoma and DLBCL. This category may help these studies to advance because so far most borderline cases either have a Burkitt lymphoma signature or an intermediate signature. Although it is clear that the WHO authors wish this category to be used sparingly it is inevitably going to become tempting to pathologists because they receive increasing numbers of small crushed needle biopsies, often with extensive necrosis, all of which mitigate against good quality in morphology, immunophenotype and genotype (Figs 14.17 and 14.18).

CHAPTER 14

H&E

Diffuse Large B-cell Lymphoma

Giemsa

CD45

CD79a

EMA

IgA

Kappa ISH

ALK

Lambda ISH

Fig 14.15 An IgA-positive sinusoidal large B-cell lymphoma expressing cytoplasmic ALK protein. ISH, in situ hybridisation.

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HE

κ

HE

λ

CD138

HHV8

CD20

EBER

mib1

Fig 14.16 Plasmablastic appearance of a large-cell lymphoma arising in an HIV+ individual expressing CD138 but CD20-. The lymphoma is light chain restricted expresses both HHV8 and EBV(EBER) and has a high proliferative rate.

CD20

Tdt

CD3

CD10

mib1

bcl2

Fig 14.17 Typical borderline B-cell lymphomas between diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma have a starry-sky low-power appearance (top left) but morphology is atypical (top right). They are CD20+ with low numbers of infiltrating T cells and CD10+. TdT is negative, the mib1+ proliferation rate is close to 100% and bcl2 is negative on the tumour cells.

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Histology

Ki67

Proliferation

CD20

bcl-2

JC1

CD10

Fig 14.18 This case, in contrast to the one in Fig 14.17, shows histological features that many pathologists would be happy to label as Burkitt lymphoma. The cytology is arguably atypical but the immunophenotype is quite against Burkitt lymphoma.

B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and classic Hodgkin lymphoma This borderline subtype is a bit easier to use than the one above because in essence it relates to the overlap between classic Hodgkin lymphoma (CHL) and DLBCL in the medi-

astinum (PMBL) [41]. These are usually the cases that look more like a DLBCL but have numbers of large abnormal mononuclear and/or binuclear cells that have some features of CHL. The main feature, however, is the shared immunophenotype whereby these cells are B cell (CD20+ CD79a+) but also express CD30 and CD15. These so-called ‘grey zone’

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CD20

CD30

CD79a

CD15

lymphomas are not unexpected, given the fact that the molecular signature of PMBL is similar to CHL and markedly different from most other DLBCLs [42] (Fig 14.19).

Conclusion Diffuse large B-cell lymphoma is now clearly a heterogeneous collection of many different clinical entities. Some are well defined but most cases remain uneasily defined as a mixture of morphological, immunocytochemical and molecular data. The challenge for haematopathologists is to apply the definitions of the new WHO classification as accurately as possible, particularly with relevance to the two new borderline categories. This should enable the gathering together of the essential clinicopathological entities to enable an ultimate WHO classification of clear relevance to both clinicians and patients.

152

Fig 14.19 Large B-cell lymphomas at the border between diffuse large B-cell lymphoma (DLBCL) and classic Hodgkin lymphoma are often sclerosing mediastinal tumours (top left) with sheets of polymorphic bizarre large cells (top right). These are CD20+ and usually at least partially CD79a+. CD30+ is frequent and some of the large cells are often CD15+ as well.

References 1. Harris NL, Jaffe ES, Stein H, et al. A revised European-American classification of lymphoid neoplasms: a proposal from the International Lymphoma Study Group [see comments]. Blood 1994;84:1361–92. 2. Engelhard M, Brittinger G, Huhn D, et al. Subclassification of diffuse large B-cell lymphomas according to the Kiel classification: distinction of centroblastic and immunoblastic lymphomas is a significant prognostic risk factor. Blood 1997;89: 2291–7. 3. Swerdlow SH, Campo E, Harris NL, et al., eds. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 4th edn. Lyon: IARC Press, 2008. 4. Haralambieva E, Pulford KAF, Lamont L, et al. Anaplastic large cell lymphomas of B cell phenotype are anaplastic lymphoma kinase (ALK) negative and belong to the spectrum of diffuse large B cell lymphomas. Br J Haematol 2000;109:584–91.

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5. Dogan A, Bagdi E, Munson P, Isaacson PG. CD10 and BCL-6 expression in paraffin sections of normal lymphoid tissue and B-cell lymphomas. Am J Surg Pathol 2000;24:846–52. 6. Weiss L, Warnke R, Sklar J, Cleary M. Molecular analysis of the t(14;18) chromosomal translocation in malignant lymphomas. N Engl J Med 1987;317:1185–9. 7. Lipford E, Wright J, Urba W, et al. Refinement of lymphoma cytogenetics by the chromosome 18q21 major breakpoint region. Blood 1987;70:1816–23. 8. Ye BH, Lista F, Lo Coco F, et al. Alterations of a zinc fingerencoding gene, BCL-6, in diffuse large- cell lymphoma. Science 1993;262:747–50. 9. Lo Coco F, Ye BH, Lista F, et al. Rearrangements of the BCL6 gene in diffuse large cell non-Hodgkin’s lymphoma. Blood 1994; 83:1757–9. 10. Chaganti SR, Chen W, Parsa N, et al. Involvement of BCL6 in chromosomal aberrations affecting band 3q27 in B- cell non-Hodgkin lymphoma. Genes Chromosomes Cancer 1998;23: 323–7. 11. Coiffier B. Rituximab therapy in malignant lymphoma. Oncogene 2007;26:3603–13. 12. Dunleavy K, Staudt LM, Wilson WH. The BCL-2 biomarker in the era of molecular diagnosis of diffuse large B-cell lymphoma. Leuk Lymphoma 2007;48:1061–3. 13. Alizadeh AA, Eisen MB, Davis RE, et al. Distinct types of diffuse large B-cell lymphoma identified by gene expression profiling Nature 2000;403:503–11. 14. Hans CP, Weisenburger DD, Greiner TC, et al. Confirmation of the molecular classification of diffuse large B-cell lymphoma by immunohistochemistry using a tissue microarray. Blood 2004; 103:275–82. 15. Amen F, Horncastle D, Elderfield K, et al. Absence of cyclin-D2 and Bcl-2 expression within the germinal centre type of diffuse large B-cell lymphoma identifies a very good prognostic subgroup of patients. Histopathology 2007;51:70–9. 16. Compagno M, Lim WK, Grunn A, et al. Mutations of multiple genes cause deregulation of NF-kappaB in diffuse large B-cell lymphoma. Nature 2009;459:717–21. 17. Dunleavy K, Pittaluga S, Czuczman MS, et al. Differential efficacy of bortezomib plus chemotherapy within molecular subtypes of diffuse large B-cell lymphoma. Blood 2009;113: 6069–76. 18. Achten R, Verhoef G, Vanuytsel L, De Wolf-Peeters C. Histiocyterich, T-cell-rich B-cell lymphoma: a distinct diffuse large B-cell lymphoma subtype showing characteristic morphologic and immunophenotypic features. Histopathology 2002;40:31–45. 19. Batchelor T, Loeffler JS. Primary CNS lymphoma. J Clin Oncol 2006;24:1281–8. 20. Willemze R, Jaffe ES, Burg G, et al. WHO-EORTC classification for cutaneous lymphomas. Blood 2005;105:3768–85. 21. Park S, Lee J, Ko YH, et al. The impact of Epstein-Barr virus status on clinical outcome in diffuse large B-cell lymphoma. Blood 2007;110:972–8. 22. Oyama T, Yamamoto K, Asano N, et al. Age-related EBVassociated B-cell lymphoproliferative disorders constitute a distinct clinicopathologic group: a study of 96 patients. Clin Cancer Res 2007;13:5124–32. 23. Hummel M, Anagnostopoulos I, Korbjuhn P, Stein H. EpsteinBarr virus in B-cell non-Hodgkin’s lymphomas: unexpected

24.

25.

26.

27.

28.

29.

30.

31.

32.

33.

34.

35.

36.

37.

38.

39.

Diffuse Large B-cell Lymphoma

infection patterns and different infection incidence in low- and high-grade types. J Pathol 1995;175:263–71. Mori N, Yatabe Y, Narita M, Kobayashi T, Asai J. Pyothoraxassociated lymphoma. An unusual case with biphenotypic character of T and B cells. Am J Surg Pathol 1996;20:760–6. Gitelson E, Al-Saleem T, Smith MR. Review: lymphomatoid granulomatosis: challenges in diagnosis and treatment. Clin Adv Hematol Oncol 2009;7:68–70. Cazals-Hatem D, Lepage E, Brice P, et al. Primary mediastinal large B-cell lymphoma. A clinicopathologic study of 141 cases compared with 916 nonmediastinal large B-cell lymphomas, a GELA (‘Groupe d’Etude des Lymphomes de l’Adulte’) study. Am J Surg Pathol 1996;20:877–88. Falini B, Venturi S, Martelli M, et al. Mediastinal large B-cell lymphoma: clinical and immunohistological findings in 18 patients treated with different third-generation regimens. Br J Haematol 1995;89:780–9. Copie-Bergman C, Gaulard P, Maouche-Chrétien L, et al. The MAL gene is expressed in Primary Mediastinal Large B-cell Lymphoma. Blood 1999;94:3567–75. Ferreri AJ, Campo E, Ambrosetti A, et al. Anthracycline-based chemotherapy as primary treatment for intravascular lymphoma. Ann Oncol 2004;15:1215–21. Ferreri AJ, Dognini GP, Govi S, et al. Can rituximab change the usually dismal prognosis of patients with intravascular large B-cell lymphoma? J Clin Oncol 2008;26:5134–6; author reply 6–7. Shimada K, Matsue K, Yamamoto K, et al. Retrospective analysis of intravascular large B-cell lymphoma treated with rituximab-containing chemotherapy as reported by the IVL study group in Japan. J Clin Oncol 2008;26:3189–95. Delsol G, Lamant L, Mariame B, et al. A new subtype of large B-cell lymphoma expressing the ALK kinase and lacking the 2;5 translocation. Blood 1997;89:1483–90. Reichard KK, McKenna RW, Kroft SH. ALK-positive diffuse large B-cell lymphoma: report of four cases and review of the literature. Mod Pathol 2007;20:310–9. Brown RS, Campbell C, Lishman SC, Spittle MF, Miller RF. Plasmablastic lymphoma: a new subcategory of human immunodeficiency virus-related non-Hodgkin’s lymphoma. Clin Oncol 1998;10:327–9. Teruya-Feldstein J, Chiao E, Filippa DA, et al. CD20-negative large-cell lymphoma with plasmablastic features: a clinically heterogenous spectrum in both HIV-positive and -negative patients. Ann Oncol 2004;15:1673–9. Oksenhendler E, Boulanger E, Galicier L, et al. High incidence of Kaposi sarcoma-associated herpesvirus-related non-Hodgkin lymphoma in patients with HIV infection and multicentric Castleman disease. Blood 2002;99:2331–6. Seliem RM, Griffith RC, Harris NL, et al. HHV-8+, EBV+ multicentric plasmablastic microlymphoma in an HIV+ Man: the spectrum of HHV-8+ lymphoproliferative disorders expands. Am J Surg Pathol 2007;31:1439–45. Chadburn A, Hyjek E, Mathew S, Cesarman E, Said J, Knowles DM. KSHV-positive solid lymphomas represent an extracavitary variant of primary effusion lymphoma. Am J Surg Pathol 2004;28:1401–16. Nador RG, Cesarman E, Chadburn A, et al. Primary effusion lymphoma: a distinct clinicopathologic entity associated with

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the Kaposi’s sarcoma-associated herpes virus. Blood 1996;88: 645–56. 40. Cesarman E, Knowles DM. The role of Kaposi’s sarcomaassociated herpesvirus (KSHV/HHV-8) in lymphoproliferative diseases. Semin Cancer Biol 1999;9:165–74. 41. Traverse-Glehen A, Pittaluga S, Gaulard P, et al. Mediastinal gray zone lymphoma: the missing link between classic Hodgkin’s

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lymphoma and mediastinal large B-cell lymphoma. Am J Surg Pathol 2005;29:1411–21. 42. Savage KJ, Monti S, Kutok JL, et al. The molecular signature of mediastinal large B-cell lymphoma differs from that of other diffuse large B-cell lymphomas and shares features with classical Hodgkin lymphoma. Blood 2003;102:3871–9.

15

Burkitt Lymphoma

Burkitt lymphoma was originally described as a lymphoreticular tumour mainly involving the jaw of young children in sub-Saharan Africa. A good response to chemotherapy was a characteristic clinical feature. Since then many cases with similar morphological features have been described in America and Europe, leading to the concept of endemic (‘African’) and non-endemic or sporadic Burkitt lymphoma. More recently cases with a similar histology have been described in immunosuppressed individuals, especially those who are HIV positive, in both endemic and sporadic areas. The borderline between diffuse large B-cell lymphoma and Burkitt lymphoma has long been an area of uncertainty. Such cases have often been referred to as Burkitt-like lymphoma but are now recognised in the provisional category of B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma [1].

Clinical features Burkitt lymphoma is most common in children (approximately a third of non-African paediatric lymphomas). Adult cases are often associated with immunodeficiency. The male : female ratio is 2 or 3:1. In African (endemic) cases, the jaws and other facial bones are often involved. In non-

African (non-endemic) cases, jaw tumours are less common: most of the cases present in the abdomen, most often involving distal ileum, caecum and/or mesentery; ovaries, kidneys or breasts may be involved. Rare cases present as acute leukaemia with cytological evidence of Burkitt lymphoma cells in the peripheral blood. This was formerly known as L3-ALL in the FAB classification but, with the demise of the latter, it is probably now better referred to as Burkitt leukaemia (and then probably cautiously until there is tissue evidence of Burkitt lymphoma).

Histology The neoplastic cells show little cell-to-cell variation and are of medium size. The nuclei are round and contain multiple nucleoli. The cytoplasm is basophilic and relatively abundant. A ‘starry-sky’ pattern is usually present, imparted by numerous benign macrophages that have ingested apoptotic tumour cells. Burkitt lymphoma cells tend to cluster around these in square shapes rather than circles, which can be helpful in distinguishing it from other tumours with similar starry-sky patterns. Mitotic figures and apoptotic nuclei are readily found in tumour cells (Fig 15.1). Cytoplasmic lipid vacuoles are usually evident on imprints or smears.

Fig 15.1 The typical histology and cytology of Burkitt lymphoma is shown at three different powers. Note the right angle formed around the tingible body macrophages (arrowed) giving the so-called ‘squaring off’ effect.

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Burkitt Lymphoma A selective infiltration of germinal centres of adjacent (otherwise uninvolved) lymph nodes is sometimes observed.

Immunohistology

Histology

B cell

The neoplastic cells express ‘pan-B’ markers (CD19, -20, -22, -79a) and are strongly positive for surface IgM. They also express CD10, an aminopeptidase, and bcl-6 is also found on normal and neoplastic germinal centre cells (supporting suggestions that Burkitt lymphoma is derived from germinal centres). CD5 and CD23 are absent as is terminal deoxynucleotidyl transferase (TdT), though some cases may be positive for CD43. Staining for Ki67 and other proliferation-associated antigens shows that all or virtually all tumour cells are positive (Figs 15.2 and 15.3). This is very helpful in diagnosis because all other aggressive B-cell lymphomas rarely have a proliferation rate >90% (Table 15.1). Unusually among lymphoid neoplasms bcl-2 is usually absent at least in endemic cases, probably also reflecting the high proliferation rate. This lack of bcl-2 is useful in differentiating Burkitt lymphoma from Burkitt-like lymphomas, most of which are bcl-2 positive. It is recommended that the few cases that express bcl-2 but are otherwise typical of Burkitt lymphoma should be accepted only if there is clear evidence of an MYC translocation in the absence of bcl-2 or bcl-6 translocations [1]. CD68 reveals the numerous ‘macrophages’ present in this tumour. Characteristically the number of CD8+ infiltrating T cells is very low (whereas they are often abundant in other lymphoma types). Challenging areas for the pathologist are cases with extensive necrosis and very small biopsies especially with the current worldwide vogue for tiny needle biopsies. In these latter it is important not to confuse Burkitt lymphoma with a small fragment of reactive germinal centre (Figs 15.4 and 15.5).

Cytogenetics Most cases have a translocation of chromosome 8 and chromosome 14. This moves the myc gene into the vicinity of the Ig heavy chain region. Less commonly the variant translocations, t(2;8) and t(8;22), juxtapose light chain genes with myc. In African (endemic) cases, the breakpoint on chromosome 14 involves the heavy chain joining region, suggesting that the translocation occurs in an early B cell, before com-

Proliferation 156

Fig 15.2 In lymph nodes Burkitt lymphoma typically has areas of starry-sky appearance, an infiltration of monomorphic, medium-sized, blastic B cells and a proliferation rate close to 100% of the tumour cells.

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Burkitt Lymphoma

CD20

CD10

CD10

Proliferation

bcl-2

Fig 15.3 Burkitt lymphoma frequently arises extranodally in tissues such as the gut, shown here. Nevertheless the histology and immunophenotype are the same as in lymphoid tissues. The presence of a reactive follicle at bottom left and bottom right highlights the positivity for CD10 and the negativity for bcl-2 in the tumour cells lying beneath the mucosa.

Table 15.1 The immunophenotypes of Burkitt lymphoma compared with its main differential diagnoses.

Burkitt lymphoma Diffuse large B-cell lymphoma Mantle cell blastic type B lymphoblastic

B cell

CD5

CD10

CD23

Ki67 (%)

TdT

bcl-2

Cyclin D1

+ + + +

− ± + −

+ ± − +

− − − −

>95 <90 <90 <90

− − − +

− ± ± ±

− − + −

B cell = CD20 and CD79a.

plete Ig gene rearrangement. In contrast, in non-endemic cases, the translocation involves the Ig heavy chain switch region, suggesting that the translocation occurs at a later stage of B-cell development [2]. It is important to be aware that the t(8;14) translocation and its variants are not restricted to Burkitt lymphoma because some typical cases of diffuse large B-cell lymphomas may also carry such translocations. These translocations can now be readily demonstrated on paraffin sections by fluorescence in situ hybridisation (FISH) and can be helpful in confirming the diagnosis (Fig 15.6).

Epstein–Barr virus Epstein–Barr virus (EBV) genomes can be demonstrated in the tumour cells in most African cases and in 25–40% of the

cases associated with AIDS, but less frequently in other cases. It should be noted though that this positivity can be demonstrated only at the RNA or DNA level because the typical EBV antigens such as LMP and EBNA2 demonstrable by immunocytochemistry are not expressed.

Subtypes The original WHO classification [3] suggested that Burkitt lymphoma should be subcategorised into three types and this has been confirmed in the 2008 update [1]: 1. Endemic: the original sub-Saharan tropical disease 2. Sporadic: occurring worldwide including in Africa and being identical pathologically but differing clinically from the endemic type

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Histology

CD79a

Proliferation (Ki67) Fig 15.4 A case of Burkitt lymphoma in a young child in whom virtually all of the tumour was necrotic shows that immunocytochemistry still has limitations. Although the B-cell antigens such as CD79a remain viable, other key markers such as Ki67 (shown here), CD10 and bcl-2 are significantly affected, so that only the small area of viable tumour (arrowed) can be phenotyped.

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HE

bcl2

HE

bcl6

HE

Burkitt Lymphoma

CD20

CD10

CD21

CD3

mib1

Fig 15.5 This was a small colonic biopsy taken from a child during investigation for gastroenterological problems. The small lymphoid area was unexpected but clearly had features of Burkitt lymphoma morphologically and immunophenotypically (CD20+ CD3− bcl2- bcl6+ CD10+ and a very high proliferative rate (mib1). The absence of follicular dendritic cells (CD21) is a helpful feature in such small samples. Further examination revealed a large mass of Burkitt lymphoma attached to the colon.

MYC BAP

IGH BAP

BCL2 BAP

BCL6 BAP

Fig 15.6 Fluorescence in situ hybridisation (FISH) in a case of Burkitt lymphoma showing a clearly split signal using break-apart probes (BAP) for MYC (arrow) but with no evidence of translocations for bcl-2 or bcl-6. The Ig heavy chain gene is also demonstrated to be rearranged (IGH). (Images courtesy of Dr Soo-Yong Tan.)

3. Immunodeficiency associated: this is largely HIV associated and should be termed Burkitt lymphoma only when it meets the strict criteria outlined and discussed above.

prognosis is highly dependent on the stage and volume of disease at presentation [4,5]. More intensive chemotherapy protocols are gradually improving survival figures worldwide [6], especially since rituximab has been introduced into these schedules [7,8].

Differential diagnosis For the histopathologist Burkitt lymphoma turns up in two guises. Either it is absolutely obvious and could be nothing else or for a variety of reasons it resembles other forms of non-Hodgkin lymphoma, most notably lymphoblastic or large cell. Burkitt lymphoma can generally be distinguished from both by proliferation-associated staining and in addition from lymphoblastic type by TdT staining.

Prognosis and treatment The tumour is highly aggressive but potentially curable (more than 80% of cases if localised). Especially in children

References 1. Swerdlow SH, Campo E, Harris NL, et al., eds. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 4th edn. Lyon: IARC Press, 2008. 2. Pelicci P, Knowles D, Magrath I, Dalla-Favera R. Chromosomal breakpoints and structural alterations of the c-myc locus differ in endemic and sporadic forms of Burkitt lymphoma. Proc Natl Acad Sci U S A 1986;83:2984–8. 3. Harris NL, Jaffe ES, Diebold J, et al. The World Health Organization classification of neoplastic diseases of the haematopoietic and lymphoid tissues: Report of the Clinical Advisory Committee Meeting, Airlie House, Virginia, November 1997. Histopathology 2000;36:69–86.

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4. Murphy SB, Fairclough DL, Hutchison RE, Berard CW. NonHodgkin’s lymphomas of childhood: an analysis of the histology, staging, and response to treatment of 338 cases at a single institution [see comments]. J Clin Oncol 1989;7:186–93. 5. Magrath I, Shiramizu B. Biology and treatment of small noncleaved cell lymphoma. Oncology 1989;3:41–53. 6. Davidson A, Desai F, Hendricks M, et al. The evolving management of Burkitt’s lymphoma at Red Cross Children’s Hospital. S Afr Med J 2006;96(9 Pt 2):950–4.

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7. Thomas DA, Faderl S, O’Brien S, et al. Chemoimmunotherapy with hyper-CVAD plus rituximab for the treatment of adult Burkitt and Burkitt-type lymphoma or acute lymphoblastic leukemia. Cancer 2006;106:1569–80. 8. Oriol A, Ribera JM, Bergua J, et al. High-dose chemotherapy and immunotherapy in adult Burkitt lymphoma: comparison of results in human immunodeficiency virus-infected and noninfected patients. Cancer 2008;113:117–25.

16

T-cell Prolymphocytic Leukaemia

T-cell prolymphocytic leukaemia (T-PLL) has emerged slowly from careful studies of chronic lymphocytic leukaemia (CLL) that showed a proportion of cases of the prolymphocytic variant had a more aggressive clinical behaviour and a T-cell phenotype [1].

now be demonstrated on paraffin sections with antigen retrieval techniques. Most cases are positive for CD4 and a proportion coexpress CD8 although some are purely CD8+ (Fig 16.2).

Cytogenetics Clinical features T-PLL is a rare condition mainly affecting adults aged >30 presenting with high white cell blood counts and usually hepatosplenomegaly and lymphadenopathy. Infiltration of the skin is seen in 20% with deep dermal infiltration, without epidermotropism or erythroderma.

Histology On blood and bone marrow smears the features are usually of a prolymphocytic leukaemia with a considerable degree of cellular polymorphism. The tissue infiltration is similar to that seen in B-CLL except that proliferation centres are absent and increased vascularity with high endothelial venules is often prominent. In the spleen both white and red pulp are infiltrated and bone marrow disease is usually diffuse [2] (Fig 16.1).

Immunophenotype

There is an inversion of chromosome 14 [inv 14(q11;q32)] in about 80% of cases with trisomy 8q also being common (50–70%). The former activates the oncogene TCL1A which can be demonstrated immunocytochemically. This is sometimes useful for diagnosis or monitoring disease after treatment as it has not been reported in any other T cell lymphoma subtypes [3]. Other less common abnormalities have been shown involving chromosomes 6 and 17. The latter often leads to p53 overexpression which can be demonstrated immunocytochemically.

Prognosis and treatment Although the disease is uncommon careful clinical studies show that the prognosis is in fact very bad regardless of therapy, with a median survival of only 7 or 8 months. More recent trials of purine analogues, such as pentostatin and cladribine, and/or the anti-CD52 monoclonal antibody alemtuzamab (CAMPATH) have shown promising responses, although not so far with much longer survival periods [4].

Tumour cells have a T-cell phenotype CD2, -3, -5 and -7 positive and are negative for TdT and CD1a, all of which can

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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T-cell Prolymphocytic Leukaemia

Fig 16.1 T-cell prolymphocytic leukaemia typically effaces the architecture of the spleen and is composed predominantly of relatively uniform small to medium-sized lymphoid cells with prominent nucleoli.

CD3

CD4

CD5

CD2

CD8

mib1

Fig 16.2 T-cell prolymphocytic leukaemia expresses CD2, CD3 and CD5. It is usually CD4+ (though this case is negative but stains for CD8). Note the unusual dot positivity of CD8. The low proliferation rate (mib1) belies the aggressive nature of this lymphoma.

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References 1. Matutes E, Brito-Babapulle V, Swansbury J, et al. Clinical and laboratory features of 78 cases of T-prolymphocytic leukemia. Blood 1991;78:3269–74. 2. Bennett J, Catovsky D, Daniel M-T, et al. Proposals for the classification of chronic (mature) B and T lymphoid leukemias. J Clin Pathol 1989;42:567–84.

T-cell Prolymphocytic Leukaemia

3. Herling M, Khoury JD, Washington LT, Duvic M, Keating MJ, Jones D. A systematic approach to diagnosis of mature T-cell leukemias reveals heterogeneity among WHO categories. Blood 2004;104:328–35. 4. Dearden CE. T-cell prolymphocytic leukemia. Clin Lymphoma Myeloma 2009;9(suppl 3):S239–43.

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17

T-cell Large Granular Lymphocytic Leukaemia and Aggressive NK-cell Leukaemia

T-cell large granular lymphocytic leukaemia (T-LGL) is a clonal expansion of large granular lymphocytes with a T-cell phenotype. It is an uncommon condition; it often takes some time to establish a diagnosis and its definition is still a source of some controversy.

the T-cell receptor TCRαβ and for the cytotoxic granuleassociated proteins perforin, granzyme B and TIA1 [2], as well as CD45RA. A few cases have a CD4 rather than a CD8 phenotype. There have been reports of some cases expressing the natural killer (NK) phenotype (CD56+ CD2+ CD3− CD8− TCRαβ−) but it is generally felt these should be included with the NK cell leukaemias.

Clinical features

Cytogenetics

Patients frequently have a long medical history with neutropenia (with or without anaemia), and autoimmune diseases especially rheumatoid arthritis and hypergammaglobulinaemia. On this background T-cell large granular lymphocytic leukaemia is characterised by a persistent lymphocytosis of predominantly granulated lymphocytes [1]. The infiltration is largely confined to the spleen and bone marrow.

There are no particular cytogenetic features apart from the fact that virtually all cases show TCR gene rearrangements indicating clear-cut clonality [3].

T-cell large granular lymphocytic leukaemia

Prognosis and treatment The disease itself seems to run an indolent almost benign course. Most patients run into problems from their associated disease and neutropenia long before the leukaemia exerts any effect.

Histology The lymphocytosis (usually more than 5 × 109/L) contains easily found lymphocytes with eccentrically placed nuclei in abundant pale-blue cytoplasm with azurophilic granules [1] (Fig 17.1). The spleen is massively infiltrated by small lymphoid cells suggesting a small lymphocytic lymphoma (Fig 17.2). In the bone marrow biopsy, lymphoma cells are typically found within the sinuses and are extremely difficult to detect by conventional examination (Fig 17.3).

Immunophenotype Most cases (more than 80%) have a clear T-cytotoxic phenotype, being CD3+ and CD8+. They are usually positive for

Aggressive NK cell leukaemia This is predominantly a leukaemic process of large granular lymphocytes with an NK phenotype rather than a T cell and a completely different clinical course.

Clinical features This is a disease only seen regularly in the far east mostly in an adolescent age group. Although patients present with leukaemia they usually have extensive tissue disease notably hepatosplenomegaly. Cutaneous involvement occurs in a small number of patients. Sometimes lymphadenopathy is

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Fig 17.1 Large granular lymphocytes in the peripheral blood.

Histology

CD3

CD20

CD8 Fig 17.2 The spleen in T-LGL shows a red pulp infiltration of CD8+ T cells.

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Histology- Giemsa

CD3

CD8 Fig 17.3 Bone marrow involvement in T-LGL is often surprisingly sparse and can be missed on cursory examination.

present as well. Virtually all cases are associated with Epstein Barr virus infection.

condition represents the leukaemic counterpart of extranodal NK-/T-cell lymphomas of nasal type or is a separate condition.

Histology Tumour cells in the peripheral blood and tissues are large granular lymphocytes. Experienced cytologists seem to be able to recognise nuances of size and pleomorphism, enabling them to separate this from the T-cell type, although most pathologists rely at least as much on the immunophenotype (Fig 17.4) [1]. Bone marrow involvement is frequently very extensive but it can be quite minimal (Fig 17.5). Then, as in T-LGL, it may be difficult to detect on routine histology requiring immunocytochemistry for its detection. Reactive histiocytes showing haemophagocytosis are often seen. Debate continues about whether this

166

Immunophenotype This variant of large granular lymphocytic leukaemia/ lymphoma has a clear-cut NK-cell phenotype being CD2+ and CD56+ and CD3− (although cytoplasmic CD3 may be positive in some cases) and CD57− [4]. These cases also express cytotoxic granule-associated proteins [2,5] and about 30% are positive for CD8. The phenotype is identical to extranodal NK-/T-cell lymphomas of nasal type but may be differentiated from blastic plasmacytoid dendritic cell neoplasms by lack of staining for TdT, bcl11a and CD123. Epstein–Barr virus (EBV) can usually be

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T-cell Large Granular Lymphocytic Leukaemia and Aggressive NK-cell Leukaemia

Histology

CD56

Fig 17.4 When large granular lymphocytic natural killer (NK)-cell leukaemia occurs, cutaneous involvement is dermal, frequently perivascular and often extending deep into subcutaneous tissues.

demonstrated either by immunostaining or EBER in situ hybridisation.

shown significant difference between these two conditions [6]. This perhaps provides the first indication that these two conditions are truly separate entities.

Cytogenetics There are no known clonal markers for this condition as natural killer cells do not undergo TCR gene rearrangement. A wide variety of genomic changes have been reported though no defining cytogenetic abnormality has been identified. A genome-wide array-based comparative genomic hybridization study comparing aggressive NK cell leukemia with extra nodal NK/T-cell lymphomas of nasal type has

Prognosis and treatment This condition contrasts markedly clinically with the T-cell variant of LGL lymphoma/leukaemia. Most patients present with an acute systemic illness including high fever. Once the diagnosis of NK-cell leukaemia is made, aggressive multiple chemotherapy is usually instigated but in spite of this most patients are dead within a few months of presentation.

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Histology

CD3

CD56

Fig 17.5 Unlike T-cell large granular lymphocytic leukaemia (T-LGL) aggressive natural killer (NK)-cell leukaemia frequently infiltrates the bone marrow extensively.

References 1. Agnarsson B, Loughran T, Starkebaum G, Kadin M. The pathology of large granular lymphocyte leukemia. Hum Pathol 1989; 20:643–51. 2. Felgar RE, Macon WR, Kinney MC, Roberts S, Pasha T, Salhany KE. TIA-1 expression in lymphoid neoplasms. Identification of subsets with cytotoxic T lymphocyte or natural killer cell differentiation. Am J Pathol 1997;150:1893–900. 3. Loughran T. Clonal diseases of large granular lymphocytes. Blood 1993;82:1–14.

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4. Suzuki R, Suzumiya J, Nakamura S, et al. Aggressive natural killer-cell leukemia revisited: large granular lymphocyte leukemia of cytotoxic NK cells. Leukemia 2004;18:763–70 5. Kagami Y, Suzuki R, Taji H, et al. Nodal cytotoxic lymphoma spectrum: a clinicopathologic study of 66 patients. Am J Surg Pathol 1999;23:1184–200. 6. Nakashima Y, Tagawa H, Suzuki R, et al. Genome-wide arraybased comparative genomic hybridization of natural killer cell lymphoma/leukemia: different genomic alteration patterns of aggressive NK-cell leukemia and extranodal NK/T-cell lymphoma, nasal type. Genes Chromosomes Cancer 2005;44:247–55.

18

Adult T-cell Lymphoma/Leukaemia

Adult T-cell leukaemia/lymphoma (ATLL) was originally described in south-western Japan, and subsequently shown to be associated with the HTLV-1 (human T-lymphotrophic virus type 1) retrovirus. This virus, HTLV-l, is also endemic in the Caribbean, where clusters of ATLL have been described, predominantly among the black population. It is seen less commonly in black patients in south-eastern USA [1].

Clinical features The median age of affected individuals is 45 years. Patients in the Caribbean tend to be slightly younger than those in Japan. Patients may present with leukaemia or generalised lymphadenopathy. The leukaemic form predominates in Japan, whereas lymphomatous presentations are more common in the western hemisphere. Skin involvement mimicking mycosis fungoides is present in about half of the cases. Other clinical findings include lymphadenopathy, hepatosplenomegaly, lytic bone lesions and hypercalcaemia. Many patients have an associated T-cell immunodeficiency often accompanied by frequent opportunistic infections such as Pneumocystis spp. Chronic and smouldering forms of the disease have been described which are associated with a more indolent clinical course [2]. There is usually minimal lymphadenopathy. The predominant clinical manifestation is skin rash, with only small numbers of atypical cells in the peripheral blood. In the chronic and smouldering forms, HTLV-1 is also found integrated within the atypical lymphoid cells.

The cells are medium to large sized with characteristic multilobated nuclei often referred to as ‘flower ‘or ‘cloverleaf’ cells.

Histology The morphology of the neoplastic cells in ATLL varies greatly from case to case. The cells may be small, with condensed nuclear chromatin and markedly polylobated nuclei [3]. Larger cells, with dispersed chromatin and small nucleoli, may also be present and in some cases they predominate. The larger cells usually show abundant cytoplasmic basophilia. Reed–Sternberg-like cells can be seen, simulating Hodgkin lymphoma [4]. In the smouldering form of ATLL, the cells may not show the typical cytological features and can be misdiagnosed as chronic lymphocytic leukaemia (CLL).

Immunohistology The neoplastic cells, regardless of the morphological appearance, are usually CD2+, CD3+, CD5+ and CD4+ T cells. Some cases express both CD4 and CD8 (Fig 18.1). They express high levels of the interleukin-2 receptor (CD25). CD7 is nearly always absent. Many cases express markers such as CCR4 or FOXP3, indicating a relationship to regulatory T cells [5]. FOXP3 is not expressed on other T-cell lymphomas making this a potentially useful diagnostic marker [6].

HTLV-1 Haematological features Tumour cells are always present in the peripheral blood typically in large numbers, although they may be relatively scarce giving the patient a normal white blood cell count.

ATLL cells contain clonally integrated HTLV-1 viral sequences, which can be detected by Southern blotting or by polymerase chain reaction (PCR). The PCR technique can be useful in the diagnosis of ATLL in non-endemic areas, where most

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Adult T-cell Lymphoma/Leukaemia

CD3

CD4

CD8

CD45RO

Ki67 Histology

Immunophenotype

Fig 18.1 This patient with adult T-cell leukaemia/lymphoma (ATLL) came from the West African HTLV-1 endemic area. This case expresses both CD4 and CD8, with the latter showing an unusual cytoplasmic dot positivity.

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individuals will not have been exposed to the virus, but is less useful when the virus is common among the population [7].

Differential diagnosis In the tissues ATLL is easily confused with other large-cell lymphomas and requires careful immunophenotyping and consideration of the clinical picture to make the right diagnosis. Once considered, detection of HTLV-1 usually puts the diagnosis onto a solid foundation.

Prognosis and treatment The acute form of the disease is associated with a poor prognosis and a median survival of under 2 years. Death is often from infections associated with an underlying immunodeficiency. Complete remissions may be obtained but the relapse rate is almost 100%. Addition of antiretroviral agents to the chemotherapy is showing promise [8]. The chronic and smouldering forms of the disease have longer survivals but may develop into the more aggressive or acute form of ATLL with an associated clinical deterioration.

Adult T-cell Lymphoma/Leukaemia

References 1. Kikuchi M, Mitsui T, Takeshita M, Okamura H, Naitoh H, Eimoto T. Virus associated adult T-cell leukemia (ATL) in Japan: clinical, histological and immunological studies. Hematol Oncol 1987;4:67. 2. Abrams M, Sidawy M, Novich M. Smoldering HTLV-associated T-cell leukemia. Arch Intern Med 1985;145:2257–8. 3. Jaffe E. Morphologic, immunologic and genetic features of HTLV1-positive adult T cell lymphomas/leukemia. In: Mason D, Harris N, eds. Human Lymphoma: Clinical implications of the REAL classification. London: Springer, 1999. 4. Duggan D, Ehrlich G, Davey F, et al. HTLV-I induced lymphoma mimicking Hodgkin’s disease. Diagnosis by polymerase chain reaction amplification of specific HTLV-I sequences in tumor DNA. Blood 1988;71:1027–32. 5. Karube K, Ohshima K, Tsuchiya T, et al. Expression of FoxP3, a key molecule in CD4CD25 regulatory T cells, in adult T-cell leukaemia/lymphoma cells. Br J Haematol 2004;126:81–4. 6. Roncador G, Garcia JF, Maestre L, et al. FOXP3, a selective marker for a subset of adult T-cell leukaemia/lymphoma. Leukemia 2005;19:2247–53. 7. Chadburn A, Athan E, Wieczorek R, Knowles D. Detection and characterization of HTLV-I associated T neoplasms in an HTLV-I non-endemic region by polymerase chain reaction. Blood 1991; 70:1500–8. 8. Matutes E. Adult T-cell leukaemia/lymphoma. J Clin Pathol 2007;60:1373–7.

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19

Extranodal NK/T-cell Lymphomas: Nasal Type

This is a clear-cut entity still searching for a really good name. It is a lymphoma of probable natural killer (NK)-cell origin, the NK/T title reflecting that the lineage is not absolutely established yet. The REAL classification called it angiocentric, reflecting its vascular localisation and destructive properties. This was not favoured by the World Health Organization (WHO) panel on the grounds that not all cases showed clear evidence of it and that other T-cell tumours could also be angiocentric. Many of these and other diagnostic difficulties arise from the fact that biopsy specimens are usually small, often with necrotic areas (Fig 19.1). It is quite possible therefore that angiocentric areas are being missed rather than that they are absent. This entity has a huge number of synonyms of which ‘lethal midline granuloma’ is probably one of the best known.

Clinical features Nasal type NK-/T-cell lymphoma has a strong association with Epstein–Barr virus (EBV) and mainly occurs in the indigenous populations of Asia and Central and South America, and is rare in North America and Europe [1]. This may suggest a genetic relationship to EBV infection in these populations. It is mainly an adult disease with a predominance of males. It presents with ulcerative destructive lesions most commonly in the nasal area and palate. Occasionally other sites of presentation are skin, testis and gastrointestinal tract, but once established in the facial areas the disease commonly spreads to these other extranodal areas quite rapidly (Fig 19.2). Lymph node and bone marrow involvement is unusual except in the final stages of widely disseminated lymphoma.

Histology As mentioned above biopsies are often small and contain much necrotic tissue. Viable tumour shows an angiocentric

and angiodestructive pattern, with vessel walls deeply infiltrated and their lumina obstructed by debris, tumour and thrombosis. This in turn leads to further ischaemia and necrosis of tissue downstream. Viable tumour cells show a broad morphological spectrum but are usually composed of medium-sized cells or a mixture of small, medium and large cells with irregular nuclei (Fig 19.3). When there is blood or bone marrow involvement the disease overlaps with and is practically indistinguishable from aggressive NK-cell leukaemia [2].

Immunophenotype Characteristically, the tumour cells are CD2+, CD43 and CD45RO+ and express the NK-cell marker CD56. Except for cytoplasmic CD3 positivity in most cases, other T- and NKcell markers are negative [3]. Occasional tumours are positive for CD7, CD8 and CD30. Similar to NK-cell leukaemia they also express cytotoxic granule-associated proteins [4]. The majority of nasal NK-/T-cell lymphomas are positive for EBV though its demonstration often requires EBER in situ hybridisation because of the infrequent or low levels of EBVrelated proteins (Fig 19.4) [5,6].

Cytogenetics No consistent findings have been reported. Immunoglobulin and T-cell receptor genes are germline in most cases.

Prognosis and treatment The outcome in this disease seems closely related to its stage. Early localised lesions respond well to radiotherapy and quite good 5-year survival rates are recorded (>50%). However, with disseminated disease these tumours are very aggressive and, regardless of therapy, 5-year survival rates are less than 10% [7].

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Extranodal NK/T-cell Lymphomas: Nasal Type

CD45RO Fig 19.1 An example of a nasal natural killer (NK)-/T-cell lymphoma biopsy in which virtually all of the tumour was necrotic (top images). Careful searching revealed one small viable focus exhibiting angiocentricity and the T-cell associated marker – CD45RO (bottom images).

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Extranodal NK/T-cell Lymphomas: Nasal Type

Histology

CD3 Fig 19.2 This patient relapsed in the skin 6 months after presenting with a nasal NK/T cell lymphoma.

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Extranodal NK/T-cell Lymphomas: Nasal Type

Fig 19.3 Example of the typical partly necrotic histology of nasal NK/T cell lymphoma. Top images show areas of necrosis; middle images show the angiocentric and destructive areas; and the bottom images show the morphology.

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Extranodal NK/T-cell Lymphomas: Nasal Type

CD3

CD56

EBV LMP

CD2

CD8

CD7

EBV Eber

CD30

TIA-1

Fig 19.4 Natural killer (NK)-/T-cell nasal lymphomas often express strong CD2, CD7 and cytoplasmic CD3. CD30, and cytotoxic proteins such as TIA-1 and CD8 may be positive. Epstein–Barr virus (EBV) LMP protein is demonstrable here but EBER (EBV RNA) in situ as usual is much stronger.

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References 1. Au WY, Ma SY, Chim CS, et al. Clinicopathologic features and treatment outcome of mature T-cell and natural killer-cell lymphomas diagnosed according to the World Health Organization classification scheme: a single center experience of 10 years. Ann Oncol 2005;16:206–14. 2. Lipford E, Margolich J, Longo D, Fauci A, Jaffe E. Angiocentric immunoproliferative lesions: a clinicopathologic spectrum of post-thymic T cell proliferations. Blood 1988;5:1674–81. 3. Ohno T, Yamaguchi M, Oka K, Miwa H, Kita K, Shirakawa S. Frequent expression of CD3 epsilon in CD3 (Leu 4)-negative nasal T-cell lymphomas. Leukemia 1995;9:44–52.

Extranodal NK/T-cell Lymphomas: Nasal Type

4. Felgar RE, Macon WR, Kinney MC, Roberts S, Pasha T, Salhany KE. TIA-1 expression in lymphoid neoplasms. Identification of subsets with cytotoxic T lymphocyte or natural killer cell differentiation. Am J Pathol 1997;150:1893–900. 5. Jaffe E. Nasal/nasal type NK/T cell lymphoma (angiocentric lymphoma) and lymphomatoid granulomatosis. In: Mason D, Harris N, eds. Human Lymphoma: Clinical implications of the REAL classification. London: Springer, 1999. 6. Medeiros L, Peiper S, Elwood L, Yano T, Rafeld M, Jaffe E. Angiocentric immunoproliferative lesions: a molecular analysis of eight cases. Hum Pathol 1991;22:1150–7. 7. Lee J, Suh C, Park YH, et al. Extranodal natural killer T-cell lymphoma, nasal-type: a prognostic model from a retrospective multicenter study. J Clin Oncol 2006;24:612–18.

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Enteropathy-associated T-cell Lymphoma

Although it was known for many years that coeliac disease could be complicated by a malignant transformation, it has only relatively recently been identified as a T-cell lymphoma and named enteropathy-associated T-cell lymphoma (EATL) [1]. Subsequent studies have divided these into two distinct diseases: EATL (called type I by some), the classic enteropathyassociated form and type II EATL, a monomorphic form not usually associated with enteropathy [2].

Classic intestinal T-cell lymphoma type I – EATL Clinical features Intestinal T-cell lymphoma is an adult disease occurring most commonly in those with a history of coeliac disease. The disease is rare but seen more commonly in Europe and the USA. It is virtually unknown in Asia. These neoplasms present with ulcerating tumours in the jejunum or ileum, giving rise to severe abdominal pain from perforation or obstruction. Disseminated disease may be present from the start or develop with progression in a number of other extranodal sites, especially lung and skin.

Histology The lymphoma is more often present as multiple ulcers than a single tumour. The morphology is variable from medium-

sized atypical lymphocytes to large almost anaplastic cells. A predominance of the latter is the most common cytology. The glandular epithelium is usually also heavily infiltrated which can be highlighted by cytokeratin staining [3].

Immunophenotype Characteristically the tumour cells are CD3+ and CD7+ with CD2, CD4, CD5 and CD8 being negative (Fig 20.1). A few are also CD8+ with CD4 being negative (Fig 20.2). Most cases express the intestinal homing antigen CD103. A varying proportion of the neoplastic cells especially the larger anaplastic ones are positive for CD30 (Fig 20.3) [3].

Cytogenetics The T-cell receptor genes are rearranged but no characteristic cytogenetic abnormality has yet been reported. Most patients have a similar HLA-DQ2/-8 genotype as seen in coeliac disease.

Prognosis and treatment In general the outlook is poor. The tumour is difficult to resect fully and relapses quickly regardless of therapy. The only long-term successes appear to be from those few cases that present with resectable localised disease [4].

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Enteropathy-associated T-cell Lymphoma

Histology

CD3

CD30

CD8

Fig 20.1 Enteropathy-associated T-cell lymphoma composed predominantly of CD3+ and CD30+ but CD8− large cells.

Immunophenotype

Monomorphic intestinal T-cell lymphoma type II – EATL Introduction and clinical features This is an intestinal lymphoma with many clinical similarities to the classic EATL described above. It differs in having a wider geographical prevalence and is found in Asia where both coeliac disease and EATL are rare. Its histology, phenotype and genotype suggest it is a distinct clinical entity [2,5].

Histology This lymphoma is composed of small- to medium-sized monomorphic lymphoid cells. The tumour forms masses but also heavily infiltrates overlying and adjacent intestinal epithelium. In contrast to EATL, although some villi involved by extension of neoplastic infiltrate are shortened, there is no significant crypt hyperplasia or villous atrophy in adjacent intestinal mucosa not infiltrated by lymphocytes.

The tumour cells have a natural killer (NK) phenotype being CD3+, CD8+, CD56+ and expressing cytotoxic granules such as TIA-1 and perforin. There is no evidence of any association with Epstein–Barr virus (EBV) (Fig 20.4). The differential diagnosis is with extranodal NK-/T-cell lymphomas that may arise in the gastrointestinal tract, from which they may be distinguished by the absence of EBV both immunocytochemically and by EBER (EBV RNA).

Genetics The T-cell receptor genes are rearranged but there is no HLA-DQ association as seen in classic EATL. No specific abnormalities have been described though a variety of MYC abnormalities are common.

Prognosis and treatment The prognosis and treatment are similar to classic EATL [6].

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Enteropathy-associated T-cell Lymphoma

Histology

CD3

CD45RO

CD8

CD30

Fig 20.2 This case of type I intestinal T-cell lymphoma has a mixed cell population with the larger cells being CD30+. CD3 staining is weak to negative on the tumour cells but CD45RO and CD8 are positive.

histology

CD3

CD30

CD45RO

Fig 20.3 This mesenteric lymph node from a resection for type I intestinal T cell lymphoma shows a paracortical infiltration of mixed cells many of which have lost CD3. The larger cells express CD30.

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CD3

CD8

Enteropathy-associated T-cell Lymphoma

CD56

Fig 20.4 Type II EATL showing small- to medium-sized monomorphic cells. The immunophenotype is characteristically CD3+, CD8+ and CD56+. Epstein–Barr virus is negative.

References 1. Isaacson P, Spencer J, Connolly C, et al. Malignant histiocytosis of the intestine: a T-cell lymphoma. Lancet 1985;ii:688–91. 2. Deleeuw RJ, Zettl A, Klinker E, et al. Whole-genome analysis and HLA genotyping of enteropathy-type T-cell lymphoma reveals 2 distinct lymphoma subtypes. Gastroenterology 2007;132: 1902–11. 3. Isaacson P. Intestinal (enteropathy-associated) T cell lymphoma. In: Mason D, Harris N, eds. Human Lymphoma: Clinical implications of the REAL classification. London: Springer, 1999.

4. Sieniawski M, Angamuthu N, Boyd K, et al. Evaluation of enteropathy-associated T-cell lymphoma comparing standard therapies with a novel regimen including autologous stem cell transplantation. Blood 2010;115:3664–70. 5. Lim MS, de Leval L, Quintanilla-Martinez L. Commentary on the 2008 WHO classification of mature T- and NK-cell neoplasms. J Hematop 2009;2:65–73. 6. Chuang SS, Chang ST, Chuang WY, et al. NK-cell lineage predicts poor survival in primary intestinal NK-cell and T-cell lymphomas. Am J Surg Pathol 2009;33:1230–40.

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Hepatosplenic T-cell Lymphoma

This is a distinct entity predominantly derived from γ/δ T cells rather than the α/β T cells of most other T-cell lymphomas [1,2]. It is very rare and affects mainly young adults with a clear male predominance. Some cases are associated with immune suppression such as post-transplantation or in association with treatment for Crohn disease [3]. As implied in the name, patients present with hepatosplenic enlargement without lymphadenopathy. The malignant cells predominantly infiltrate the sinusoids in both the spleen and the liver. They are of medium size and monomorphic in appearance, with round or slightly irregular nuclei showing loosely condensed chromatin and pale cytoplasm. Bone marrow involvement is invariably present at diagnosis but detectable only with immunohistochemistry. As in the spleen and liver, the malignant cells are mainly found within the sinuses. The lymphoma cells usually express the γ/δ T-cell receptor protein and not α/β T-cell receptor protein [4]. Most cases are positive for CD3, CD2 and cytotoxic granule-associated proteins (Fig 21.1) [5]. However, they

typically express TIA-1 and granzyme M but not granzyme B and perforin. Thus, they type as mature, non-activated cytotoxic T cells. A few express CD8 and CD56 but CD4 and CD5 are absent. Isochromosome 7q and trisomy 8 have been reported in over two-thirds of patients [6,7]. There appears to be no evidence of an association with Epstein–Barr virus (EBV) in this disorder. Rare cases showing comparable morphological features but expressing α/β T-cell receptors have been reported [8,9]. The predominant differential diagnosis is with other T-cell lymphomas that can express predominantly sinusoidal infiltration of liver and spleen. The clue to distinguishing them comes from the lack of involvement of other tissues and the characteristic immunophenotype of γ/δ T-cell lymphoma. Occasionally the sinusoidal infiltration can cause confusion with some B-cell lymphomas, notably hairy cell leukaemia, but here immunophenotyping provides a clear distinction. This lymphoma is clinically aggressive with most patients dying of the disease within 2 years despite chemotherapy [3].

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Hepatosplenic T-cell Lymphoma

γ/δ TCR

Liver

Spleen

CD3

Bone marrow CD3 Fig 21.1 This figure highlights the sinusoidal patterns of hepatosplenic γ/δ T-cell lymphoma in the liver, spleen and bone marrow.

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Hepatosplenic T-cell Lymphoma

References 6. 1. Farcet J, Gaulard P, Marolleau J, et al. Hepatosplenic T-cell lymphoma: sinusal/sinusoidal localization of malignant cells expressing the T-cell receptor γδ. Blood 1990;75:2213–9. 2. Cooke CB, Krenacs L, Stetler-Stevenson M, et al. Hepatosplenic T-cell lymphoma: a distinct clinicopathologic entity of cytotoxic gamma delta T-cell origin [see comments]. Blood 1996;88: 4265–74. 3. Belhadj K, Reyes F, Farcet JP, et al. Hepatosplenic gammadelta T-cell lymphoma is a rare clinicopathologic entity with poor outcome: report on a series of 21 patients. Blood 2003;102: 4261–9. 4. Vega F, Medeiros LJ, Gaulard P. Hepatosplenic and other gammadelta T-cell lymphomas. Am J Clin Pathol 2007;127:869–80. 5. Salhany KE, Feldman M, Kahn MJ, et al. Hepatosplenic gammadelta T-cell lymphoma: ultrastructural, immunophenotypic,

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7.

8.

9.

and functional evidence for cytotoxic T lymphocyte differentiation. Hum Pathol 1997;28:674–85. Wang CC, Tien HF, Lin MT, et al. Consistent presence of isochromosome 7q in hepatosplenic T gamma/delta lymphoma: a new cytogenetic–clinicopathologic entity. Genes Chromosomes Cancer 1995;12:161–4. Alonsozana EL, Stamberg J, Kumar D, et al. Isochromosome 7q: the primary cytogenetic abnormality in hepatosplenic gammadelta T cell lymphoma [letter]. Leukemia 1997;11:1367–72. Suarez F, Wlodarska I, Rigal-Huguet F, et al. Hepatosplenic alphabeta T-cell lymphoma: an unusual case with clinical, histologic, and cytogenetic features of gammadelta hepatosplenic T-cell lymphoma. Am J Surg Pathol 2000;24:1027–32. Macon WR, Levy NB, Kurtin PJ, et al. Hepatosplenic alphabeta T-cell lymphomas: a report of 14 cases and comparison with hepatosplenic gammadelta T-cell lymphomas. Am J Surg Pathol 2001;25:285–96.

22

Subcutaneous Panniculitis-like T-cell Lymphoma and Primary Cutaneous γ/δ T-cell Lymphoma

Subcutaneous panniculitis-like T-cell lymphoma This is a rare condition labelled a provisional entity in the REAL classification but now accepted as an independent entity in the new World Health Organization (WHO) classification. The clinical picture is characteristic, presenting as subcutaneous nodular lesions without obvious systemic involvement. Haemophagocytosis in many organs, not just bone marrow, frequently complicates this condition either at presentation or by developing at a later stage [1]. The histological picture is one of subcutaneous panniculitis with an infiltrate of polymorphic atypical cells. The dermis and epidermis are usually not involved, unlike most other cutaneous infiltrations by T-cell lymphomas. Frequently the subcutaneous fat is rimmed by neoplastic cells which is often described as a diagnostic feature but is in fact relatively common in many conditions causing panniculitis, both neoplastic and inflammatory (Fig 22.1) [2]. The cytological picture is variable, similar to that seen in other peripheral T-cell lymphomas. Necrosis and degenerative change in the fat are common. The immunophenotype is typically CD2+, CD3+ and CD8+. The tumour has an α/β phenotype showing positivity for βF1 antibody. The most important differential diagnosis is inflammatory panniculitis, with which it is often confused especially in cases of lupus panniculitis. Usually reactive panniculitis has a broader mix of inflammatory cells including plasma cells and aggregates of B cells that are rare in subcutaneous panniculitis-like T-cell lymphoma. In lymphomas the proliferation rate is generally high and evidence of clonal T-cell gene rearrangement is also helpful (Fig 22.2) [3]. There is, however, no simple way of avoiding this error so pathologists should always be wary of missing this lymphoma when panniculitis is widespread and progressive. Cases studied to date have shown no evidence of Epstein–Barr virus, distinguishing this condition from

extranodal natural killer (NK)-/T-cell lymphomas of nasal type. No specific cytogenetic abnormalities have been reported. The rarity of this condition and its frequent confusion with other diseases, including the overlap with other T-cell lymphomas, have caused great confusion in therapy and estimation of prognosis. Careful review of the literature and cases estimate that, if strict diagnostic criteria are applied and cases of NK-/T-cell lymphoma and cutaneous γ/δ T-cell lymphoma are excluded, the overall survival rate with standard therapy is good, being about 80% survival at 5 years [4].

Primary cutaneous γ/δ T-cell lymphoma Many if not most of these lesions were previously considered as variants of subcutaneous panniculitis-like T-cell lymphoma [5,6]. Although it frequently involves subcutaneous tissues, then having a panniculitis-like appearance, it usually also clearly involves dermis and epidermis (at least in other areas or in subsequent biopsies). This is a disease of adults and presents either similar to subcutaneous panniculitis-like T-cell lymphoma or as a particularly aggressive looking mycosis fungoides. Very astute and experienced dermatologists may be able to suspect it clinically but the diagnosis comes from careful histological examination and complete immunophenotyping. The lymphoma is CD2+, CD3+ and CD7+, and expresses γ/δ receptor which is now detectable on paraffin sections. Some cases express CD56 and CD30. Tumour cells are usually negative for CD4, CD8 and CD5, and always for βF1, the marker of α/β receptors on paraffin sections (Fig 22.3). It is worth identifying this condition separately because it has a much worse prognosis than both subcutaneous panniculitis-like T-cell lymphoma and mycosis fungoides [4]. Response to treatment is generally poor with short median survival periods of little more than year.

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Subcutaneous Panniculitis-like T-cell Lymphoma and Primary Cutaneous γ/δ T-cell Lymphoma

Low power

Cytology

Haemophagocytosis in the bone marrow

Fig 22.1 A straightforward case of subcutaneous panniculitis-like T-cell lymphoma in subcutaneous fat with an associated haemophagocytic syndrome, seen here in the bone marrow. Areas of necrosis are common.

CD2

mib1

CD3

Fig 22.2 Case of subcutaneous panniculitis-like T-cell lymphoma that could be confused with reactive panniculitis. However, the malignant T cells are easily appreciated on T-cell staining (CD2 and CD3) and highlighted by the proliferation staining (mib1), which would not be high in an inflammatory lesion. 186

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Subcutaneous Panniculitis-like T-cell Lymphoma and Primary Cutaneous γ/δ T-cell Lymphoma

γ/δ receptor

γ/δ receptor

βF1

CD4

CD8

CD68

Fig 22.3 Primary cutaneous γ/δ T-cell lymphoma infiltrates dermis and epidermis as well as subcutaneous fat. It expresses the γ/δ receptor protein and is negative for βF1. The tumour cells are CD4− and CD8−. An associated haemophagocytic syndrome often occurs when there is panniculitic involvement, as in this case shown here with CD68 staining in the bone marrow.

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Subcutaneous Panniculitis-like T-cell Lymphoma and Primary Cutaneous γ/δ T-cell Lymphoma

References 1. Gonzalez C, Medeiros L, Braziel R, Jaffe E. T-cell lymphoma involving subcutaneous tissue: a clinicopathologic entity commonly associated with hemophagocytic syndrome. Am J Surg Pathol 1991;15:17–27. 2. Cerroni L, Gatter KC, Kerl H. Skin Lymphoma: The illustrated guide. Oxford: Wiley-Blackwell, 2009. 3. Cerroni L. Lymphoproliferative lesions of the skin. J Clin Pathol 2006;59:813–26.

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4. Willemze R, Jansen PM, Cerroni L, et al. Subcutaneous panniculitis-like T-cell lymphoma: definition, classification, and prognostic factors: an EORTC Cutaneous Lymphoma Group Study of 83 cases. Blood 2008;111:838–45. 5. Cerroni L, Kerl H, Gatter K. An Introduction to Skin Lymphoma. Oxford: Blackwell’s Scientific, 1998. 6. Arnulf B, Copie-Bergman C, Delfau-Larue MH, et al. Nonhepatosplenic gammadelta T-cell lymphoma: a subset of cytotoxic lymphomas with mucosal or skin localization. Blood 1998;91:1723–31.

23

Mycosis Fungoides/Sézary Syndrome

These are a complicated group of diseases often requiring considerable clinical input in order to make an appropriate diagnosis. Both show infiltration of skin with epidermotropism by small- to medium-sized cells with cerebriform nuclei. In the REAL classification Sézary syndrome is considered as a variant or related condition in which the abnormal cells are also found in the blood. The World Health Organization (WHO) classification believes that there are sufficient clinical differences to separate the two conditions into separate entities [1,2]. From a pathologist’s viewpoint, however, they are almost identical and separation is made largely on clinical grounds.

Clinical features These are predominantly diseases of elderly people and progress slowly with evolution of skin lesions from small patches and plaques through to frank tumours. Sometimes the disease remits or resolves of its own accord. In the later stages the restriction to skin (and blood in Sézary syndrome) is lost, dissemination occurs to many organs and tissues, and large-cell transformation supervenes (Fig 23.1). Rather surprisingly involvement of bone marrow by Sézary syndrome is difficult to demonstrate even late in the progress of the disease.

Histology Lesions in the skin all show infiltration into the epidermis (‘epidermotropism’) but apart from that virtually any other

pattern can be seen giving rise to a huge variety of histologies reflected in the many subtypes or variants described by dermatopathologists [3]. Broadly, and at the risk of oversimplification, they tend to start rather subtly, being difficult to distinguish from inflammatory lesions, and progress slowly, waxing and waning, to form large extensive infiltrative skin tumours. At this stage both entities tend to disseminate and may transform into large T-cell tumours as a terminal event. When present small clusters of three or more intraepidermal tumour cells (Pautrier microabscesses consisting of cerebriform cells) can be helpful in making a diagnosis. Lymph node involvement tends to occur at the advanced stage when it is an obvious T-cell lymphoma. However, lymphadenopathy from reactive dermatopathic change is common in the course of the disease. It can be difficult to determine at which point the node is beginning to be infiltrated by malignant cells unless molecular detection mechanisms for T-cell receptor rearrangement are used.

Immunophenotype The tumour cells are mature T cells labelled by CD2, CD3 and CD5 in paraffin sections. Most are CD4+, although a small number of CD8+ cases have been described (Fig 23.2). The loss of the CD7 antigen is frequent, although it should be noted that T cells lacking CD7 can be seen in benign cutaneous lymphoid infiltrates. A proportion of the cells are CD30+ and this number rises as the tumour progresses. This can be a helpful feature in early cutaneous lesions in alerting the pathologist to the diagnosis, although it is by no means specific [4] (Fig 23.3).

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Mycosis Fungoides/Sézary Syndrome

CD30 Fig 23.1 Obvious lymph node involvement usually occurs at advanced stages when the tumour could often not be distinguished from a nodal T-cell lymphoma without the preceding history. In this case there is a hint of a dermatopathic pattern in the low-power haematoxylin and eosin (H&E)-stained image, but the tumour at higher power is clearly a high-grade aggressive one with many large abnormal cells highlighted in the CD30 staining.

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Mycosis Fungoides/Sézary Syndrome

Histology

CD4

CD8 Fig 23.2 An example of a CD8+ case of mycosis fungoides (the only one in the authors’ collection) that in all other respects looked and behaved like typical mycosis fungoides.

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Mycosis Fungoides/Sézary Syndrome

Histology

CD3

Pautrier’s microabscess

CD3

CD30

CD3

Fig 23.3 Early lesions of mycosis fungoides in the patch or plaque stage are the most common ones received by pathologists for diagnosis. By the time tumours develop the diagnosis is usually well established, making tumour biopsies relatively rare.

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Mycosis Fungoides/Sézary Syndrome

Cytogenetics

References

Apart from clonal rearrangements of the T-cell receptor genes no specific cytogenetic abnormalities have been described for either condition [5,6]. There is evidence for abnormalities on chromosome 10q perhaps in association with disease progression [7]. HTLV-1 may be associated with some cases.

1. Harris NL, Jaffe ES, Diebold J, et al. The World Health Organization classification of hematological malignancies report of the Clinical Advisory Committee Meeting, Airlie House, Virginia, November 1997. Mod Pathol 2000;13:193–207. 2. Swerdlow SH, Campo E, Harris NL, et al., eds. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. 4th edn. Lyon: IARC Press, 2008. 3. Cerroni L, Gatter KC, Kerl H. Skin Lymphoma: The illustrated guide. Oxford: Wiley-Blackwell, 2009. 4. Ralfkiaer E, Wantzin G, Mason D, Hou-Jensen K, Stein H, Thomsen K. Phenotypic characterization of lymphocyte subsets in mycosis fungoides. Am J Clin Pathol 1985;84:610–19. 5. Weiss LM, Hu E, Wood GS, et al. Clonal rearrangements of T-cell receptor genes in mycosis fungoides and dermatopathic lymphadenopathy. N Engl J Med 1985;313:539–44. 6. Aisenberg A, Krontiris T, Mak T, Wilkes B. The gene for the beta chain of the T-cell receptor is rearranged in mycosis fungoides and dermatopathic lymphadenopathy. N Engl J Med 1985;313: 529–33. 7. Scarisbrick JJ, Woolford AJ, Russell-Jones R, Whittaker SJ. Loss of heterozygosity on 10q and microsatellite instability in advanced stages of primary cutaneous T-cell lymphoma and possible association with homozygous deletion of PTEN. Blood 2000;95: 2937–42.

Prognosis and treatment The pathological diversity of these diseases is reflected in their clinical behaviour which ranges from a virtually benign skin condition to a virulent malignancy that can be fatal in a remarkably short period. The most important prognostic factor is the extent of disease at presentation. Mycosis fungoides tends to be more slowly progressive than Sézary syndrome which is disseminated at diagnosis and has a poorer prognosis. This alone is a good reason for separating the two conditions clinically. Treating the diseases is almost as much an art form as a science and includes the use of ultraviolet light and cytokines as well as radiotherapy and chemotherapy.

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24

Peripheral T-cell Lymphoma

It has been recognised for many years that lymphoid neoplasms can be derived from T cells, but their scarcity (10– 20% of all non-Hodgkin lymphomas) compared with B–cell neoplasms, and their heterogeneous morphological features, means that they have proved difficult to classify. The Kiel classification listed these under six different categories [1], but the REAL scheme simplified the categorisation of T-cell neoplasms by creating a large group of ‘peripheral T-cell lymphoma unspecified’ [2]. This was due to the uncertainties and difficulties in providing reproducible diagnoses and was coined with the intention that further study would elucidate the underlying disease entities. This has slowly taken place with many extranodal varieties especially in skin and gastrointestinal tract, being now recognised as specific entities in the 2008 World Health Organization (WHO) classification [3].

Clinical features The clinical presentation is quite variable but usually presents in adults with generalised lymphadenopathy, hepatosplenomegaly and bone marrow involvement. Other extranodal sites such as the skin and gut may also be involved, especially as the disease progresses. A few patients may present with a haemophagocytic syndrome. Constitutional symptoms, including fever and night sweats, are common, as is pruritus.

Many of these lymphomas are highly vascularised with numerous arborising vessels resembling high endothelial venules. Inflammatory cells are frequently present, consisting of eosinophils, plasma cells and histiocytes (Fig 24.2). Three variants are recognized in the 2008 WHO classification. 1. Lymphoepithelioid or Lennert lymphoma 2. T-zone lymphoma 3. Follicular T-cell lymphoma. If the epithelioid histiocytes are numerous and clustered, the neoplasm fulfils the criteria for ‘lymphoepithelioid cell lymphoma’ or ‘Lennert lymphoma’. However, in the REAL and WHO classifications lymphoepithelioid cell lymphoma is considered a morphological variant of peripheral T-cell lymphoma and not a distinctive clinicopathological entity (Fig 24.3). Peripheral T-cell lymphoma may preferentially involve the paracortical region of lymph nodes and in some cases this architectural pattern is striking, with sparing of follicles. Such cases are referred to as T-zone lymphoma (Fig 24.4). The neoplastic cells usually have a moderate amount of pale cytoplasm but otherwise they resemble other peripheral T-cell lymphomas. The third variant involves follicular colonisation by neoplastic T cells which can at times look remarkably like B-cell follicular lymphoma [4]. It has been suggested that the follicular variant may represent a border zone with angioimmunoblastic T cell lymphoma [5].

Immunophenotype Histology The cellular composition is typically heterogeneous, usually with a mixture of small and large atypical lymphoid cells, some of which may show striking Reed–Sternberg-like features (Fig 24.1).

The pattern of antigen expression varies from case to case. This may reflect yet to be defined clinicopathological entities, but to date immunophenotypical criteria have not delineated any clearly subtypes. Most cases have a mature T-cell phenotype with CD3 and CD4 (or less commonly

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Peripheral T-cell Lymphoma

CD3 Fig 24.1 A selection of cells from peripheral T-cell lymphomas showing Hodgkin lymphoma and Reed–Sternberg-like features. Their T-cell nature is clearly demonstrated by CD3 immunostaining.

Case 1: H&E

Case 2: H&E

CD3

CD3

CD68

Fig 24.2 Two cases of peripheral T-cell lymphoma show how varied the histology is. This is partially accounted for by associated reactive cells such as macrophages shown in case 2 by immunostaining for CD68.

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Peripheral T-cell Lymphoma

H&E

CD3

Proliferation

Fig 24.3 When the number of macrophages is high and they take on an epithelioid cytology, the T-cell peripheral lymphoma is often referred to as the lymphoepithelioid variant or the Lennert lymphoma.

CD8) being present, but loss (albeit usually partial) of one or more of the pan-T-cell antigens (CD3, CD5, CD2 or CD7) is seen in most cases (75% of cases), CD7 being the most frequent [6] (Fig 24.5). Most cases are derived from α/β T-cells, rather than γ/δ T cells. This is reflected by about 80% of cases expressing βF1, but not γ/δ T-cell receptor protein. Both of these proteins can now be demonstrated in paraffin sections. CD30 (and also less frequently epithelial membrane antigen [EMA]) is expressed on large cells in these lymphomas. Indeed the

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whole tumour may be composed of large CD30+ cells (Fig 24.6). Epstein–Barr virus (EBV) is generally negative. Monoclonal antibodies detecting individual variable chains of the T-cell receptor are increasing in number, so that in the future it may be possible to determine the clonality of some peripheral T-cell lymphomas by this means. Proliferation rates tend to be higher than B-cell lymphomas of comparable cytological grade and increase with the size of the tumour cells. Pathologists need to be alert to aberrant expression of B-cell markers, which does occur in these

CHAPTER 24

Peripheral T-cell Lymphoma

Histology

CD3

CD4

CD20

CD8

CD30

Fig 24.4 A peripheral T-cell lymphoma composed of medium-sized cells mainly occupying the paracortex (note the residual B-cell areas) may be referred to as T zone. The B-cell areas can be well preserved with germinal centres which might lead to confusion with reactive lymphadenopathy or follicular lymphoma. Occasional CD30+ cells are present, although this T-cell lymphoma would be considered CD30−.

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Peripheral T-cell Lymphoma

CD3

CD4

CD8

CD43

CD45RO

Fig 24.5 Many T-cell lymphomas show considerable heterogeneity for T-cell markers such as CD3 or CD4. This can make it difficult to decide the phenotype, e.g. in this case one has to look carefully to see that it is the CD4+ cells that are atypical not the CD8+ ones. Support for the T-cell lineage can be obtained with antibodies against antigens such as CD43 and CD45RO, but these should not be used alone because they are not lineage specific.

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Peripheral T-cell Lymphoma

CD3 low power

CD3 high power

CD20

CD30

Proliferation

Histology

Fig 24.6 A CD30+ non-anaplastic peripheral T-cell lymphoma. Note the nodular growth pattern that occurs from time to time, the heterogeneity of CD3 expression and the high proliferative rate.

tumours although much less commonly than with T-lymphoblastic lymphomas [7] (Fig 24.7).

Differential diagnosis Reactive lesions

Cytogenetics The T-cell receptor genes show clonal rearrangements but otherwise no consistent cytogenetic abnormalities have been described [8,9].

Overall, the diagnosis of peripheral T-cell lymphoma is much more difficult than that of B-cell lymphoma because there is no marker for clonality (in contrast to the light chain restriction in B-cell lymphoma). In addition, quite commonly, malignant T cells are admixed with a number of

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CD20

Fig 24.7 Example of a peripheral T-cell lymphoma showing positivity for CD20. Usually the CD20 positivity is on only a percentage of the tumour cells and the rest of the lymphoma shows a T-cell phenotype, as shown here for CD3, CD5 and CD2.

non-neoplastic T cells, and it is sometimes difficult to decide what is the malignant population. The loss of one or more T-cell antigens may be of diagnostic value for differentiating malignant lymphomas from benign T-cell proliferations that consist of T cells expressing all of the T-cell-associated antigens with a mixture of CD4+ and CD8+ cells.

Anaplastic large-cell lymphomas CD30 expressing large T-cell lymphomas can be distinguished from anaplastic T-cell lymphomas on morphological grounds. However, the important clinical distinction is to separate the tumours possessing the t(2;5) chromosomal translocation from the others, usually on the basis of nuclear ALK protein staining. It may well be that the remainder of the anaplastic non-ALK-expressing T-cell tumours would be better considered as part of the spectrum of peripheral T-cell lymphoma (as the B-cell cases are considered part of the large B-cell lymphomas). In contrast to anaplastic large-cell lymphomas, peripheral T-cell lymphomas consisting of a predominant population of large cells are most commonly strongly positive for CD3 and, when expressed, CD30 is weaker and more heterogeneous.

Hodgkin lymphoma Occasionally it can be difficult to decide whether a case is a T-cell lymphoma or a Hodgkin lymphoma. Most haematopathologists recognise this and try to make a diagnosis based on a balance of morphology and immunophenotype. Thus, a lymphoma with imperfect Reed–Sternberg-like cells,

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CD3

CD5

CD2

an atypical lymphoid background and a predominantly T-cell phenotype would get the nod for T-cell lymphoma.

Prognosis and treatment The clinical course is aggressive, although complete remissions may be obtained with combination chemotherapy. The relapse rate and survival rate (40% at 5 years) are worse in peripheral T-cell lymphoma than in large B-cell lymphomas (60% at 5 years). Patients may respond to standard treatment designed for B-cell-aggressive lymphoma but those in partial response after first-line treatment, whatever its type, have a poor outcome. Poor prognostic features are disseminated disease especially with bone marrow involvement and positivity in the tumour cells for EBV.

References 1. Lennert K, Feller A. Histopathology of Non-Hodgkin’s Lymphomas. 2nd edn. New York: Springer-Verlag, 1992. 2. Harris NL, Jaffe ES, Stein H, et al. A revised European-American classification of lymphoid neoplasms: a proposal from the International Lymphoma Study Group [see comments]. Blood 1994;84:1361–92. 3. Swerdlow SH, Campo E, Harris NL, et al., eds. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 4th edn. Lyon: IARC Press, 2008.

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4. de Leval L, Savilo E, Longtine J, Ferry JA, Harris NL. Peripheral T-cell lymphoma with follicular involvement and a CD4+/bcl−6+ phenotype. Am J Surg Pathol 2001;25:395–400. 5. Huang Y, Moreau A, Dupuis J, et al. Peripheral T-cell lymphomas with a follicular growth pattern are derived from follicular helper T cells (TFH) and may show overlapping features with angioimmunoblastic T-cell lymphomas. Am J Surg Pathol 2009;33: 682–90. 6. Wood KM, Pallesen G, Ralfkiaer E, Warnke R, Gatter K, Mason DY. Heterogeneity of CD3 antigen expression in T-cell lymphoma. Histopathology 1993;22:311–17.

Peripheral T-cell Lymphoma

7. Warnke RA, Jones D, Hsi ED. Morphologic and immunophenotypic variants of nodal T-cell lymphomas and T-cell lymphoma mimics. Am J Clin Pathol 2007;127:511–27. 8. Lepretre S, Buchonnet G, Stamatoullas A, et al. Chromosome abnormalities in peripheral T-cell lymphoma. Cancer Genet Cytogenet 2000;117:71–9. 9. Rizvi MA, Evens AM, Tallman MS, Nelson BP, Rosen ST. T-cell non-Hodgkin lymphoma. Blood 2006;107:1255–64.

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Angioimmunoblastic T-cell Lymphoma

First described as a clinical syndrome named angioimmunoblastic lymphadenopathy with dysproteinaemia (AILD) in 1975 [1]. It was initially believed to be an abnormal immune reaction usually leading to death from infection as a result of immunodeficiency, although spontaneous resolutions were recorded. Gradually increasing numbers of cases were reported to evolve into lymphomas. Now this entity is generally accepted as a T-cell lymphoma, because most cases show clonal rearrangements of T-cell receptor genes [2].

Clinical features Although one of the more common subtypes of T-cell lymphoma, this is still a relatively rare disorder, but is clinically distinctive. Patients typically have a systemic disease, with generalised lymphadenopathy, which is rarely massive, fever, weight loss, skin rash and polyclonal hypergammaglobulinaemia. The course is moderately aggressive, with occasional spontaneous remissions or protracted responses to steroids, and infectious complications. Progression to high-grade lymphoma of T- or occasionally B-cell type occurs.

Histology The nodal architecture is effaced; peripheral sinuses are typically open and even dilated, but the abnormal infiltrate often extends beyond the capsule into the perinodal fat. Reactive follicles with germinal centres may be present in a few early cases with the neoplastic infiltrate confined to the paracortex. As the disease progresses these are usually overrun and disappear. The node typically has a pale, or depleted appearance at low power. There is a prominent proliferation of arborising high endothelial vessels, many of which show thickened or hyalinised periodic acid–Schiff (PAS)-positive walls (Fig 25.1). Expanded aggregates of follicular dendritic cells (FDCs), visible on immunostained sections, surround the proliferat-

ing blood vessels and may have the appearance of ‘burntout’ germinal centres. The lymphoid infiltrate usually appears relatively sparse, compared with other lymphomas, probably because of the large number of FDCs (Fig 25.2). The lymphoid cells are a mixture of small lymphocytes, immunoblasts and a characteristic type of atypical ‘clear’ cell, which usually has a round to slightly indented nucleus and abundant, pale or clear cytoplasm. These cells occur singly or in small aggregates or sheets. Epithelioid histiocytes, plasma cells and eosinophils may be admixed. Other organs such as skin and bone marrow are often involved, although it may take careful immunostaining to detect the atypical T cells hidden in their vascular matrix (Fig 25.3).

Immunophenotype Many of the large and atypical cells express pan-T antigens such as CD2, CD3 and CD5, and are usually of CD4 subtype. Further characterisation of these cells shows that they have the characteristic phenotype of follicular helper T cells, being CD10+, bcl6+, CXCL13+ and PD-1+. These may not all be positive and generally can be demonstrated only on a proportion of the abnormal cells. If present they are extremely helpful in distinguishing AITL from other T-cell lymphomas. Scattered large immunoblast-like B cells are also present. About two-thirds of these B cells are latently infected by Epstein–Barr virus (EBV) and are positive for EBV latent membrane antigens (demonstrated by double immunostaining studies) or EBV RNA by EBER in situ staining (Fig 25.4). In some examples, staining for κ and λ light chains will highlight the large B cells, and a polytypic staining pattern may be the clue that one is dealing with a reactive large B-cell proliferation complicating angioimmunoblastic T-cell lymphadenopathy (AITL) rather than a large B-cell lymphoma.

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Hypocellularity

Angioimmunoblastic T-cell Lymphoma

Vascularity

Mixed infiltrate

Fig 25.1 The histology of AILT is characterized by arborizing vessels with prominent endothelial cells and large immunoblasts ( arrows).

CD31

Proliferation

CD21 Fig 25.2 Angioimmunoblastic T-cell lymphadenopathy (AITL) is characterized by arborizing blood vessels (CD31) surrounded by proliferating blast cells (Ki67). Immunostaining for FDC antigens shows the hyperplastic and disorganised FDC meshworks encircling blood vessels. Note the commonly found dilated sinuses (arrow).

CHAPTER 25

Angioimmunoblastic T-cell Lymphoma

CD3 portfolio Histology

CD79a

CD3 low power

EBV LMP

EBV EBER

Fig 25.4 A portfolio of different areas in a angioimmunoblastic T-cell lymphadenopathy (AITL) stained for CD3 shows that most but not all of the blast cells are T cells. The others are Epstein–Barr virus (EBV)-positive B cells (CD79a). EBER, EBV RNA.

CD3 high power

CD31

Fig 25.3 Angioimmunoblastic T-cell lymphadenopathy (AITL): bone marrow (and skin) involvement can be difficult to detect without immunostaining.

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HE

CD20

Angioimmunoblastic T-cell Lymphoma

CD3

CD21

CD10

Fig 25.5 This case was initially thought to be a follicular variant of peripheral T-cell lymphoma with the residual B-cell follicles shown by CD20, CD21 and CD10 staining.

Variable numbers of large cells stain for CD30 antigen. Polyclonal plasma cells are always present as are large numbers of reactive CD8+ small lymphocytes. Expanded FDC clusters are present around the branching thick-walled venules. This latter feature (along with the CD10 positivity) is useful in distinguishing this disorder from other T-cell lymphomas.

Cytogenetics T-cell receptor (TCR) genes are rearranged in 75%, IgH in 10% [3,4], and EBV genomes are detected in many cases with mutations in LMP-1 associated with transformation into large B-cell lymphomas [5]. Trisomy 3 and/or 5 may also occur [6].

Differential diagnosis The main differential diagnoses are with peripheral T-cell lymphomas, Hodgkin lymphoma and reactive lymphadenopathy.

when a predominantly large-cell lymphoma (sometimes even of B type) is developing (Figs 25.5 and 25.6).

Hodgkin lymphoma The presence of atypical large Reed–Sternberg-like cells in a mixed background can cause confusion with Hodgkin lymphoma. This is especially so if the abnormal cells are EBV+ B cells expressing both CD15 and CD30 [7]. A distinction may be made with molecular studies but highlights the current grey zone between Hodgkin and T- and B-cell lymphomas.

Atypical hyperplasia There is no doubt that in some lymph nodes the appearances are very reminiscent of AITL but no definitive neoplastic cells can be seen. If molecular studies fail to disclose a T- or B-cell clone, they should be considered as atypical but reactive even though some cases progress into AITL. In some patients presenting with clinical symptoms suggesting AITL, the first biopsy may show non-specific lymph node changes. Some authorities consider the presence of high numbers of CD10+ cells in the interfollicular areas indicative of early involvement by AITL.

Peripheral T-cell lymphoma unspecified Many of the features described in AITL can be seen in some peripheral T-cell lymphomas (PTCLs) but it is the combination of all in the same tissue that characterises AITL. Even so, in some cases a distinction may be difficult especially in the follicular variant of PTCL and in advanced AITL

Prognosis and treatment There is as yet no consensus on the best form of treatment for this disease, partly because its rarity prevents good

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Angioimmunoblastic T-cell Lymphoma

CD2

CD21

CD3

CD4

CD20

CD10

Fig 25.6 At relapse a few months later the case shown in figure 25.6 clearly shows the pattern of angioimmunoblastic T-cell lymphadenopathy (AITL) with the follicles now completely overwhelmed by a typical arborising vascular tumour with a pan-T-cell phenotype showing CD10 positivity.

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Angioimmunoblastic T-cell Lymphoma

clinical trials but also from its heterogeneous clinical presentation. Many therapies have been tried from steroids through to high-dose chemotherapy with bone marrow transplantation. Antibody treatment with alemtuzumab is also currently being evaluated [8]. Although longer survival periods are being reported with intensive therapy [9], the disease tends to runs an aggressive course with about twothirds of patients dying from infection and the remainder from high-grade lymphomas (Fig 25.7).

References

H&E

Grocott silver

1. Frizzera G, Moran E, Rappaport H. Angio-immunoblastic lymphadenopathy with dysproteinemia. Lancet 1974;i:1070–3. 2. Dogan A, Attygalle AD, Kyriakou C. Angioimmunoblastic T-cell lymphoma. Br J Haematol 2003;121:681–91. 3. O’Connor NT, Crick JA, Wainscoat JS, et al. Evidence for monoclonal T lymphocyte proliferation in angioimmunoblastic lymphadenopathy. J Clin Pathol 1986;39:1229–32. 4. Griesser H, Feller A, Lennert K, Minden M, Mak TW. Rearrangement of the beta chain of the T cell antigen receptor and immunoglobulin genes in lymphoproliferative disorders. J Clin Invest 1986;78:1179–84. 5. Knecht H, Martius F, Bachmann E, et al. A deletion mutant of the LMP1 oncogene of Epstein–Barr virus is associated with evolution of angioimmunoblastic lymphadenopathy into B immunoblastic lymphoma. Leukemia 1995;9:458–65. 6. Schlegelberger B, Zhang Y, Weber-Matthiesen K, Grote W. Detection of aberrant clones in nearly all cases of angioimmunoblastic lymphadenopathy with dysproteinemia-type T-cell lymphoma by combined interphase and metaphase cytogenetics. Blood 1994;84:2640–8. 7. Quintanilla-Martinez L, Fend F, Moguel LR, et al. Peripheral T-cell lymphoma with Reed-Sternberg-like cells of B-cell phenotype and genotype associated with Epstein–Barr virus infection. Am J Surg Pathol 1999;23:1233–40. 8. Enblad G, Hagberg H, Erlanson M, et al. A pilot study of alemtuzumab (anti-CD52 monoclonal antibody) therapy for patients with relapsed or chemotherapy-refractory peripheral T-cell lymphomas. Blood 2004;103:2920–4. 9. Weidmann E, Gramatzki EM, Wilhelm M, Mitrou PS. Diagnosis and actual therapy strategies in peripheral T-cell lymphomas: summary of an international meeting. Ann Oncol 2004;15:369–74.

anti pneumocystis antibody Fig 25.7 Pneumocystis infection of the lung from a postmortem examination of a patient with angioimmunoblastic T-cell lymphadenopathy (AITL). Note how difficult the organisms are to see using H&E.

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26

Anaplastic Large-cell Lymphoma

This neoplasm was first identified in 1985 as a lymphoma composed of very large cells and a cohesive growth pattern in lymph nodes [1]. Previously many cases had been diagnosed as Hodgkin lymphoma or even metastatic carcinoma and melanoma. The discovery that it usually expresses the Ki-1 or CD30 antigen and also has characteristic histological, immunophenotypical, cytogenetic and clinical features, led to its proposal as a distinct entity. It has been referred to as ‘Ki-1 lymphoma’ in the past. The CD30 molecule was originally detected with the monoclonal antibody Ki-1 which was thought to show selectivity for Reed–Sternberg cells. However, it is now known to be a member of the tumour necrosis factor (TNF) receptor family and a marker of activation on many lymphoid cells, B and T, both benign and malignant [2,3]. Most cases are of T- or null-cell phenotype. In the World Health Organization (WHO) classification, as in the REAL classification, only systemic anaplastic large-cell lymphoma (ALCL) of T or null phenotype is recognised as a distinct entity. B-cell lymphomas, consisting of a predominant population of cells with anaplastic morphology and positive for CD30, are classified in the category of diffuse large B-cell lymphoma. Primary systemic anaplastic large-cell lymphoma must also be distinguished from ALCL of primary cutaneous type and from other subtypes of T- or B-cell lymphoma with anaplastic features and/or CD30 expression. More recently a chromosomal translocation between chromosome 2 and chromosome 5 has been described in cases of T- and null-cell ALCL. This causes a unique expression of a tyrosine kinase ALK (anaplastic lymphoma kinase) in the nuclei and cytoplasm of these cells, detectable with an antiALK monoclonal antibody. These findings have expanded the morphological spectrum of ALCL and divided the condition into two entities: the ALK+ ALCLs (sometimes called ALKomas) and those that are negative for ALK protein. These have now been separated into two subtypes in view of the evidence that they are clinically distinct entities [4,5].

Anaplastic large-cell lymphoma – ALK+ Clinical features ALCL ALK+ accounts for about 10% of all high-grade nonHodgkin lymphomas and 10–20% of childhood lymphomas. Its peak incidence is in young teenagers and it is a rare disease after the age of 30 [6]. It is slightly more common in males [7]. Patients often present with multiple lymphadenopathies, stage III–IV disease and fever. Skin involvement is frequent and found in approximately 30% of cases [8]. Other common extranodal sites include bone, soft tissues, lung and liver. Less frequent findings include mediastinal mass, bulky disease, gut or splenic infiltration, and central nervous system involvement. Bone marrow involvement is difficult to detect in routine sections, but almost a third of the bone marrows that are considered to be uninvolved on conventional examination will show scattered malignant cells detectable only with immunohistochemistry using CD30 or ALK antibodies.

Histology Lymph nodes involved by ALCL usually show partial effacement of their normal structure. The tumour cells are large, with an unusual appearance and tend to grow within lymphoid sinuses. They form confluent sheets and spread to adjacent paracortical regions. With the availability of antibodies to the ALK protein, the neoplasm can now be subdivided morphologically. ALK staining has highlighted the fact that each of these subtypes contains a characteristic large cell with a horseshoe- or embryonic-shaped nucleus (the ‘hallmark cell’) [9]. With experience pathologists can begin to recognise these variants of ALCL on this basis [10].

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Histology

Anaplastic Large-cell Lymphoma

CD2

CD30

EMA

Perforin

Fig 26.1 The typical cytology, subcapsular infiltration and immunophenotype of common type anaplastic large-cell lymphoma (ALCL). This type accounts for most cases of ALCL whether ALK+ or not.

Common type The neoplastic cells have a bizarre appearance in tissue sections and are usually larger than in any other type of lymphoma. They have a moderate amount of cytoplasm (greyish–violet in Giemsa-stained sections). The nuclei have variable profiles (e.g. round, oval, kidney shaped) and, although Reed–Sternberg-like cells may be present, they are uncommon. Mitotic figures are frequent. In cytology preparations (e.g. lymph node imprints), the size and bizarre appearance of the cells with cytoplasmic vacuoles are also evident (Figs 26.1 and 26.2).

Lymphohistiocytic type This subtype is observed more often in the first or second decade of life. The neoplastic cells resemble those seen in the common type, although they are sometimes slightly smaller and are mixed with numerous macrophages which can be demonstrated by labelling for CD68. Their appear-

ance is characteristic (eccentric nuclei with dense chromatin and wide rims of acidophilic cytoplasm) and they may be so numerous as to obscure the neoplastic cells. However, the background population of lymphoma cells can be demonstrated by staining for CD30. The neoplastic cells express proliferation-associated antigens such as Ki67, whereas the macrophages do not, clearly establishing that this is not a histiocytic malignancy (Fig 26.3).

Giant cell rich This can be distinguished from the common type by the many multinucleated giant cells, often reminiscent of Reed– Sternberg cells (Fig 26.4).

Small cell subtype [11] This variant of ALCL is commonly misdiagnosed as a pleomorphic T-cell lymphoma because most of the cells are not large but medium sized and express a pan-T-cell phenotype,

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Anaplastic Large-cell Lymphoma

Sinusoidal infiltration pattern

Predominantly cytoplasmic

Mixed nuclear and cytoplasmic

Predominantly nuclear

Fig 26.2 The immunocytochemical patterns of ALK staining in common-type anaplastic large-cell lymphoma (ALCL) with the t(2;5) translocation.

Histology

CD30

CD8

210

CD68

ALK

Fig 26.3 The histological and immunocytochemical features of the lymphohistiocytic type of anaplastic large-cell lymphoma (ALCL).

CHAPTER 26

Anaplastic Large-cell Lymphoma

Histology medium and high power

CD30

ALK

Fig 26.4 The histological and immunocytochemical features of the giant cell variant of anaplastic large-cell lymphoma (ALCL).

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Anaplastic Large-cell Lymphoma

Histology

Perivascular location

CD30

ALK Fig 26.5 The histological and immunocytochemical features of the small-cell variant of anaplastic large-cell lymphoma (ALCL).

typically CD2+ and CD3+. However, interspersed among the predominant small- to medium-sized cells are numbers of large atypical cells (usually CD3−) with the characteristic features of the keynote cell of ALCL. These cells are often in a perivascular location and have the typical ALCL phenotype of positivity for CD30, EMA (epithelial membrane antigen) and ALK. The predominant small-cell population most commonly shows a restricted nuclear ALK staining, confirming their nature as part of the tumour and distinguishing them from peripheral T-cell lymphomas. In addition, these cells are only weakly positive for CD30 and EMA (Fig 26.5).

Hodgkin like This is a controversial subtype most of which, as originally described, represent ALK− cases of Hodgkin lymphoma mimicking ALCL. The tumour cells have a clearer cytoplasm

212

than in the common type. They tend to grow in a cohesive pattern, giving rise to nodules surrounded by fibrotic collagen bands, thus resembling nodular sclerosing Hodgkin lymphoma. Intrasinusoidal spread is usually observed, whereas it is a very rare finding in Hodgkin lymphoma. These cases are recognised and diagnosed as ALCL by their positivity for ALK protein because most of the so-called ‘Hodgkin-like’ anaplastic large cell lymphomas (negative for ALK protein) are likely to be classic Hodgkin lymphomas rich in neoplastic cells (Fig 26.6).

Sarcomatoid and other morphological variants ALCLs showing sarcomatous features, even if associated with common type areas, are rare but often get misdiagnosed as sarcomas. Occasional ALCLs with ‘signet ring’ cells, and hence possible confusion with carcinomas, have also been reported.

CHAPTER 26

Anaplastic Large-cell Lymphoma

Low power nodular sclerosis like pattern

High power Cytology

EMA

ALK

Low power Histology

Sinusoidal growth pattern

CD30

EMA

CD 15

Fig 26.6 Two cases illustrating Hodgkin-like ALCL. The first case (top two rows) is ALK positive, whereas the second case (bottom) shows a sinusoidal growth pattern and is CD30 and EMA positive, but negative for ALK and CD15.

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Anaplastic Large-cell Lymphoma

Immunophenotype One of the hallmarks of the tumour is the expression of CD30, but it should be noted that this marker is also expressed in many other lymphoid neoplasms, including Hodgkin lymphoma and some peripheral T-cell lymphomas. Labelling of neoplastic cells for CD30 shows that it is associated with the cell membrane or present in a dot-like pattern in the cytoplasm. Most ALCLs (>90%) are positive for EMA [12]. The staining pattern for EMA is similar to that seen with CD30, although, in some cases, only a proportion of malignant cells are positive. The tumour can usually (60– 75%) be categorised on the basis of one or more markers such as CD2, CD3, CD4 or CD5 as a T-cell neoplasm. However, CD3 staining of malignant cells is usually weak and observed in less than a third of cases. The best T-cell marker (although not T-cell restricted) is CD43 because twothirds of ALCLs are positive for this marker. A minority of cases express CD4 or CD8 antigen. Many of the remaining cases are categorised as null because no clear lineage profile is found. Most of these are probably of T-cell origin because genetic studies show evidence of T-cell receptor (TCR) abnormalities and T-cell-associated granule proteins such as TIA1, perforin and granzyme B can be demonstrated immunocytochemically. Another marker expressed by the neoplastic cells is CD45 (65%), whereas the expression of CD15 is exceedingly rare (<1% of cases) and even then is only present on a small number of the anaplastic cells. Markers such as CD25, HLA-DR, CDw70, CD71 and the proliferation-associated antigen Ki67 suggest that anaplastic large cell lymphoma arises from proliferating, activated lymphoid cells. BCL-2 staining has been consistently negative. As discussed above most cases of T- and null-cell systemic ALCL, especially those occurring in children and adults, express ALK positivity as a marker of t(2;5). This is present as nuclear or nuclear and cytoplasmic staining (75% of cases). Approximately 25% of cases are associated with variant translocations that give rise to either membranous or cytoplasmic ALK staining.

Fig 26.7 It is now possible to combine immunostaining with in situ hybridisation to show translocations such as ALK on the very cells containing a particular marker – ALK-1 in this case. (Image courtesy of Dr Soo Yong Tan.)

and its associated hybrid protein. Thus, the staining is nuclear, nucleolar and cytoplasmic in cases with the ‘classic’ t(2;5) (NPM-ALK) translocation. In cases associated with the variant translocations the staining is restricted to the cytoplasm but with some subtle differences between them. In tumours associated with t(1;2) (TPM3-ALK) [15] the staining is restricted to the cytoplasm with more intense staining immediately beneath the membrane. In t(2;17)-positive cases (CLTCL-ALK), the staining is also restricted to the cytoplasm but shows a marked granular pattern. The translocation involving the moesin gene is so far the only one associated with membrane staining [16].

Anaplastic large cell lymphoma – ALK−

Cytogenetics A translocation occurs in about 75% of cases of ALCL between chromosome 2 and 5, juxtaposing portions of two different genes, the ALK gene, encoding a tyrosine kinase receptor in the insulin receptor supergene family and the nucleophosmin (NPM) gene [13]. This fusion gene encodes a hybrid NPM/ALK protein (‘p80’), which leads to an overexpression of ALK protein (not normally expressed in mature tissues except for a weak expression in nerve cells) with a nuclear localization [14] (Fig 26.7). Alternative translocations involving ALK on chromosome 2 and other genes on chromosomes 1, 2, 3, 17, 19, 22 and X have been described. In any given case, the subcellular distribution of ALK staining is highly indicative of the translocation involved

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These lymphomas are identical morphologically to those described above but lack expression of ALK protein. The main reason for separating these from ALK+ cases is their different age range and considerably more aggressive clinical course.

Clinical features These are lymphomas of middle age (40–65 years) and predominantly affect lymph nodes. Extranodal sites that may be involved include skin, soft tissues and gut.

Histology The cytology and architecture of the tumours is identical to that of the ALK+ cases described above. The same variant

CHAPTER 26

Anaplastic Large-cell Lymphoma

Histology

CD30

CD15

Fig 26.8 Here is a case originally diagnosed as Hodgkin-like anaplastic large-cell lymphoma (ALCL) ALK−. However, the immunophenotype is clearly that of Hodgkin lymphoma CD30+ and CD15+ but ALK−. This illustrates the dilemma facing pathologists – whether to call this case Hodgkin lymphoma rich in neoplastic cells or ALCL ALK – Hodgkin like. The authors favour the former diagnosis.

morphologies are also seen with the exception of the smallcell variant (which can only be identified on the basis of ALK staining). As a result of the lack of ALK positivity care must be taken to exclude cases of classic Hodgkin lymphoma from Hodgkin-like variants. A useful guide to diagnosis is given in the 2008 WHO classification which states: ‘emphasis should be placed on CD30 expression; if a large cell lymphoma of non-B-cell phenotype shows strong, homogeneous CD30 expression, especially if this is strongest in the Golgi and membrane regions, and the morphological features are consistent with ALCL, it should be classified as ALCL ALK−. Fortunately the distinction between ALCL

ALK- and PTCL, NOS currently carries no major clinical implications’ [17]. This last sentence is reassuring because this is often a very difficult distinction to make.

Immunophenotype All tumour cells should be uniformly positive for CD30 with the pattern described above. Otherwise the immunophenotype with the exception of ALK staining is the same as ALCL ALK+. In the distinction from classic Hodgkin lymphoma (CHL), PAX5 (but not MUM1) is useful because many cases of CHL are positive whereas only rare cases of ALCL have been reported as positive [18]. EBV is always absent and

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Anaplastic Large-cell Lymphoma

CD4

CD30

Fig 26.9 Typical case of primary cutaneous anaplastic large-cell lymphoma (ALCL) which expresses CD4 but has almost lost CD3. All these cases are ALK− and EMA−.

CD15 positivity if present is very rare (Fig 26.8). If either of these is present a diagnosis of CHL or PTCL not otherwise specified (NOS) should be carefully considered.

ALCL develops in the skin as a secondary neoplasm or represents skin involvement in patients with systemic disease, it tends to be aggressive [20,21].

Differential diagnosis

Lymphomatoid papulosis and regressing atypical histiocytosis

Primary cutaneous ALCL

These may show strong similarities to cutaneous ALCL but clinically display a relatively benign pattern of behaviour. Both undergo spontaneous regression and contain, respectively, scattered or relatively high numbers of CD30+, large, atypical T cells, which have a monoclonal pattern of TCR gene rearrangement. The diagnosis of these cutaneous lesions can be very challenging and is beyond the scope of this volume. A detailed discussion for these interested may be found in the companion volume to this on skin lymphoma [22].

Primary cutaneous ALCL must be distinguished from primary systemic ALCL [19]. Even though the two lesions share a common morphology and phenotype (CD30 expression), primary cutaneous ALCLs remain restricted to the skin in 75% of cases, and respond well to local treatment (surgery or radiation) (Fig 26.9). Before treatment they may grow rapidly, although they can also occasionally show spontaneous regression. The prognosis in these cases is relatively good (median survival: 42 months). In contrast, when

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Fig 26.10 A metastatic carcinoma resembling an anaplastic large-cell lymphoma (ALCL).

Anaplastic Large-cell Lymphoma

Histology

Metastatic carcinoma ALCL can be mistaken for poorly differentiated carcinoma or melanoma because they all invade tissues with a cohesive growth pattern. A simple antibody panel usually separates them (Table 26.1). There are some minor exceptions to the above in that some carcinomas (especially embryonal) and melanomas express albeit weakly CD30 (Fig 26.10).

Cytokeratins

Table 26.1 Antibodies to distinguish anaplastic large-cell lymphoma (ALCL) Antibody

ALCL

Carcinoma

Melanoma

CD30 T cell Cytokeratins S100/HMB45/melan A

+ ± − −

− − + −

− − − +

Malignant histiocytosis/true histiocytic lymphoma This entity is very rare but may be confused with the macrophage-rich variant of ALCL. Immunocytochemical labelling usually enables a distinction (Table 26.2).

Hodgkin lymphoma The distinction from Hodgkin lymphoma can be difficult and on occasions may necessitate a subjective opinion based on a best interpretation of the diagnostic features. Again a small panel of antibodies can be most helpful (Table 26.3).

Diffuse large B-cell lymphoma with anaplastic morphology Occasional cases of diffuse large B-cell lymphoma may show the morphological, including a sinusoidal growth pattern, and phenotypic features (CD30 positivity) of ALCL. In contrast to ALCL, these tumours express several B-cell antigens and the t(2;5) chromosomal translocation is not found in such cases [23].

Table 26.2 Distinction of anaplastic large-cell lymphoma (ALCL) from malignant histiocytosis Antibody

ALCL

Malignant histiocytosis

Reactive macrophages

CD30

+

−

−

CD68

−

+

+

Proliferation marker, e.g. Ki67

+

+

−

a

a

Granular staining for some antibodies reactive with CD68, such as KP-1, may be seen, but other antibodies, such as PGM1, are negative.

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Anaplastic Large-cell Lymphoma

Table 26.3 Distinction of anaplastic large-cell lymphoma (ALCL) from Hodgkin lymphoma Antibody

ALCL

Hodgkin lymphoma

CD30 CD15 EMA ALK B cell (especially PAX-5) T cell CD43 EBV (LMP1/EBER)

+ −/+ (rare) + ± − ± + −

+ + (75%)/− −/+ (<5%) − ± (heterogeneous staining) − − + (60%)/−

Tumours other than ALCL expressing ALK protein In lymphoproliferative disorders ALK protein expression is restricted to ALCL with the only exception being rare, diffuse, large B-cell lymphomas expressing cytoplasmic IgA and showing an immunoblastic or plasmoblastic, rather than an anaplastic, morphology [24]. These tumours express the full-length ALK receptor and not the truncated form. Rare cases of rhabdomyosarcoma and inflammatory myofibroblastic tumours that express ALK have also been reported [25].

First bone marrow

Lymph node 1 month later

Lymph node CD30

Pelvic biopsy 3 months later

Pelvic cytology

Pelvic biopsy CD30

Fig 26.11 The extremely good response rate to therapy and survival of anaplastic large-cell lymphoma (ALCL) ALK+ has prompted some discussion as to how malignant these lesions truly are and whether they need such high-grade therapy. It is difficult to see how a trial could be set up to test this, so anecdotal evidence may be all there is to go on. This case illustrates one of the first that the authors saw after the description of Ki-1 lymphoma in the mid-1980s. The patient presented pregnant with profound anaemia and thrombocytopenia, so much so that a bone marrow biopsy was taken. This was reported as normal. A month later generalised lymphadenopathy was noted and a biopsy taken. Suspicions were raised that this contained one small subcapsular focus of the newly described ALCL. Amid general scepticism and fears for the pregnancy, the patient was allowed to continue without treatment. All seemed to quieten down until after the delivery, when the patient became suddenly paraplegic. CT scans showed massive bony infiltration and destruction. High-grade therapy brought a swift response, the paraplegia reversed, and the patient has remained alive and well more than 12 years later. Subsequent examination showed both biopsies to be ALK+ (not shown here). If this case is typical then ALK+ ALCL is a naturally very aggressive lesion that does need prompt treatment.

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Prognosis and treatment ALCL ALK+ in children and adolescents is associated with a much better prognosis than ALCL ALK− in adults, with a relapse-free survival rate at 5 years of about 80%. Survival based on the expression of ALK protein, including children and adults, shows a favourable prognostic significance for ALK expression (5-year survival rate of 80% for ALK+ compared with 40% for ALK− tumours). No difference has been found between NPM-ALK+ tumours and the other ALK variants [26]. Relapses are not uncommon (30% of cases) but they are highly chemosensitive [27]. Therapy for these cases uses the conventional approaches used for other types of high-grade lymphoma (Fig 26.11).

References 1. Stein H, Mason D, Gerdes J, et al. The expression of the Hodgkin’s disease associated antigen Ki-1 in reactive and neoplastic lymphoid tissue: evidence that Reed–Sternberg cells and histiocytic malignancies are derived from activated lymphoid cells. Blood 1985;66:848–58. 2. Durkop H, Latza U, Hummel M, Eitelbach F, Seed B, Stein H. Molecular cloning and expression of a new member of the nerve growth factor receptor family that is characteristic for Hodgkin’s disease. Cell 1992;68:421–7. 3. Smith CA, Gruss HJ, Davis T, et al. CD30 antigen, a marker for Hodgkin’s lymphoma, is a receptor whose ligand defines an emerging family of cytokines with homology to TNF. Cell 1993;73:1349–60. 4. Stein H, Foss HD, Durkop H, et al. CD30(+) anaplastic large cell lymphoma: a review of its histopathologic, genetic, and clinical features. Blood 2000;96:3681–95. 5. ten Berge RL, Oudejans JJ, Ossenkoppele GJ, Meijer CJ. ALKnegative systemic anaplastic large cell lymphoma: differential diagnostic and prognostic aspects – a review. J Pathol 2003;200:4–15. 6. Falini B, Pileri S, Zinzani PL, et al. ALK+ lymphoma: clinicopathological findings and outcome. Blood 1999;93:2697–706. 7. Greer J, Kinney M, Collins R, et al. Clinical features of 31 patients with Ki-1 anaplastic large-cell lymphoma. J Clin Oncol 1991;9:539–47. 8. Brugieres L, Deley MC, Pacquement H, et al. CD30(+) anaplastic large-cell lymphoma in children: analysis of 82 patients enrolled in two consecutive studies of the French Society of Pediatric Oncology. Blood 1998;92:3591–8. 9. Benharroch D, Meguerian-Bedoyan Z, Lamant L, et al. ALKpositive lymphoma: a single disease with a broad spectrum of morphology. Blood 1998;91:2076–84. 10. Falini B, Bigerna B, Fizzotti M, et al. ALK expression defines a distinct group of T/null lymphomas (‘ALK lymphomas’) with a wide morphological spectrum. Am J Pathol 1998;153:875–86. 11. Kinney M, Collins R, Greer J, Whitlock J, Sioutos N, Kadin M. A small-cell-predominant variant of primary Ki-1 (CD30)+ T-cell lymphoma. Am J Surg Pathol 1993;17:859–68.

Anaplastic Large-cell Lymphoma

12. Delsol G, Al Saati T, Gatter K, et al. Coexpression of epithelial membrane antigen (EMA), Ki-1, and interleukin-2 receptor by anaplastic large cell lymphomas: diagnostic value in so-called malignant histiocytosis. Am J Pathol 1988;130:59–70. 13. Pulford K, Lamant L, Morris SW, et al. Detection of anaplastic lymphoma kinase (ALK) and nucleolar protein nucleophosmin (NPM)-ALK proteins in normal and neoplastic cells with the monoclonal antibody ALK1. Blood 1997;89:1394–404. 14. Morris SW, Kirstein MN, Valentine MB, et al. Fusion of a kinase gene, ALK, to a nucleolar protein gene, NPM, in non-Hodgkin’s lymphoma. Science 1994;263:1281–4. 15. Lamant L, Dastugue N, Pulford K, Delsol G, Mariame B. A new fusion gene TPM3-ALK in anaplastic large cell lymphoma created by a (1;2)(q25;p23) translocation. Blood 1999;93: 3088–95. 16. Tort F, Pinyol M, Pulford K, et al. Molecular characterization of a new ALK translocation involving moesin (MSN-ALK) in anaplastic large cell lymphoma. Lab Invest 2001;81:419–26. 17. Swerdlow SH, Campo E, Harris NL, et al., eds. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 4th edn. Lyon: IARC Press, 2008. 18. Feldman AL, Law ME, Inwards DJ, Dogan A, McClure RF, Macon WR. PAX5-positive T-cell anaplastic large cell lymphomas associated with extra copies of the PAX5 gene locus. Mod Pathol 2010;23:593–602. 19. Willemze R, Jaffe ES, Burg G, et al. WHO-EORTC classification for cutaneous lymphomas. Blood 2005;105:3768–85. 20. Beljaards RC, Kaudewitz P, Berti E, et al. Primary cutaneous CD30-positive large cell lymphoma: definition of a new type of cutaneous lymphoma with a favorable prognosis. A European Multicenter Study of 47 patients. Cancer 1993;71:2097–104. 21. de Bruin P, Beljaards R, van Heerde P, et al. Differences in clinical behaviour and immunophenotype between primary cutaneous and primary nodal anaplastic large cell lymphoma of T-cell or null cell phenotype. Histopathology 1993;23:127–35. 22. Cerroni L, Gatter KC, Kerl H. Skin Lymphoma: The illustrated guide. Oxford: Wiley-Blackwell, 2009. 23. Haralambieva E, Pulford KAF, Lamont L, et al. Anaplastic large cell lymphomas of B cell phenotype are anaplastic lymphoma kinase (ALK) negative and belong to the spectrum of diffuse large B cell lymphomas. Br J Haematol 2000;109:584–91. 24. Delsol G, Lamant L, Mariame B, et al. A new subtype of large B-cell lymphoma expressing the ALK kinase and lacking the 2;5 translocation. Blood 1997;89:1483–90. 25. Griffin CA, Hawkins AL, Dvorak C, Henkle C, Ellingham T, Perlman EJ. Recurrent involvement of 2p23 in inflammatory myofibroblastic tumors. Cancer Res 1999;59:2776–80. 26. ten Berge RL, Oudejans JJ, Ossenkoppele GJ, et al. ALK expression in extranodal anaplastic large cell lymphoma favours systemic disease with (primary) nodal involvement and a good prognosis and occurs before dissemination [see comments]. J Clin Pathol 2000;53:445–50. 27. Brugieres L, Quartier P, Le Deley MC, et al. Relapses of childhood anaplastic large-cell lymphoma: treatment results in a series of 41 children – a report from the French Society of Pediatric Oncology. Ann Oncol 2000;11:53–8.

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27

Hodgkin Lymphoma

Unlike non-Hodgkin lymphomas little has changed in Hodgkin lymphoma since the original classification of Jackson and Parker in the 1940s. At the famous Rye conference in 1965, this was refined to its present-day form. The REAL and the World Health Organization (WHO) classification continue this. The only changes are those of emphasis by splitting Hodgkin lymphoma into classic types and nodular lymphocyte predominance [1–3] and the name itself – dropping disease for lymphoma [4]. In spite of this stability in classification Hodgkin lymphoma has been and still continues to be an enigmatic disease defying precise definition. Pathologists and oncologists are now familiar and comfortable with the entity but find great difficulty in explaining it to a naive audience. Hodgkin lymphoma is typically a lymph node disease of younger patients. Extranodal presentations are rare, although systemic symptoms especially in classic Hodgkin lymphoma are common. The current WHO and REAL classification of Hodgkin lymphoma is: • Nodular lymphocyte predominant • Classic types: Nodular sclerosis Mixed cellularity Lymphocyte rich Lymphocyte depleted. Finally one should be aware that not all cases of classic Hodgkin lymphoma can be fitted into any of these categories, so that at times one is justified in making a diagnosis of Hodgkin lymphoma unspecified.

pathological entity [5]. This disorder has also been referred to as ‘nodular paragranuloma’, a designation coined by the Kiel group based on the term ‘paragranuloma’ introduced much earlier by Jackson and Parker. It accounts for approximately 80% of the cases previously categorised as lymphocyte-predominant Hodgkin lymphoma.

Clinical features There are several clinical features that distinguish nodular lymphocyte-predominant Hodgkin lymphoma from classic Hodgkin lymphoma. The age distribution is unimodal with a single peak in the fourth decade, contrasting sharply with the two age peaks, one in the third and the other in the seventh decade, found in nodular sclerosis Hodgkin lymphoma. The disease shows a predilection to involve single cervical, axillary or inguinal lymph nodes rather than groups of nodes, and is seldom disseminated (most cases are stage I or II). Extranodal disease and bone marrow involvement are rare, especially at presentation. Relapses of nodular lymphocyte-predominant Hodgkin lymphoma are frequent irrespective of the treatment given to the patients. They are not always to the same tumour or even other forms of Hodgkin lymphoma, but to non-Hodgkin lymphomas, mostly large B cell [6]. Some patients develop a reactive lymphadenopathy characterised by follicular hyperplasia with progressive transformation of germinal centres; this may occur before their diagnosis or even afterwards when they are in remission. Unlike other types of Hodgkin lymphoma involvement of the mediastinum is uncommon.

Histology

Nodular lymphocyte-predominant Hodgkin lymphoma The nodular form of lymphocyte-predominant Hodgkin lymphoma is so different from the other types of Hodgkin lymphoma that it should be recognised as a distinct clinico-

The most obvious histological feature is the presence of large nodules composed principally of small lymphoid cells. These nodules have many similarities to progressively transformed germinal centres seen in many reactive lymph nodes. Within the nodules and to a lesser extent in the surrounding diffuse areas, large cells with lobated nuclei, often referred to as

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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‘L&H’ (‘lymphocytic and histiocytic’) or ‘popcorn’ cells, are scattered. The 2008 WHO Classification now recommends that these be called LP (lymphocyte-predominant) cells [3]. These appearances are most apparent after formalin fixation and are not as clear with other fixatives (i.e. Bouin stain). They were traditionally regarded as variants of Reed– Sternberg cells but they show clear cytological differences from classic Reed–Sternberg cells, and there is no evidence that the two cell types are closely related. It should be stressed that in nodular LP Hodgkin lymphoma, large atypical cells other than LP cells, some resembling large immunoblasts or even Reed–Sternberg-like cells, may be seen. In these cases careful immunophenotyping is needed to ensure a definite diagnosis. The background infiltrate of small lymphocytes and epithelioid histiocytes seen in this disorder also tends to differ in appearance from the more heterogeneous cellular infiltrate, including neutrophils, plasma cells and eosinophils, typical of classic Hodgkin lymphoma (nodular sclerosis and mixed cellularity) [7] (Fig 27.1). In addition in nodular LP Hodgkin lymphoma follicular dendritic cells may become dissociated from their follicular networks to form Warthin– Finkeldey-like polykaryocytes. The definition of diffuse LP Hodgkin lymphoma and its relationship to other types of Hodgkin lymphoma remain controversial. This category appears heterogeneous although

Hodgkin Lymphoma

most of the cases in the past would probably now be called T-cell-rich B-cell lymphoma.

Immunohistology The nodules contain small B lymphocytes (bearing IgM and IgD) and extensive meshworks of follicular dendritic reticulum cells (FDCs). They thus represent expanded primary, rather than secondary, follicles because germinal centres are absent. The small B-lymphoid cells do not show evidence of monoclonality. Many of the T cells within the nodules form rosettes around the LP cells. These cells are furthermore distinguished by being frequently positive for CD57. The LP cells show clear differences from classic Reed–Sternberg cells in their marker profile being positive for most B-cell antigens. In contrast to Reed–Sternberg cells, LP cells are uniformly positive for CD20, CD79a, J chain (found only in Ig-synthesising B cells) and CDw75 (a marker of germinal centre cells usually absent on Reed–Sternberg cells) (Fig 27.2). They also express the CD45 antigen and the transcription factors BOB1 and OCT2. These are clonal cells and this can often be demonstrated by light chain staining where they usually express κ light chains only [8]. Unlike most germinal centre B cells they are negative for CD10 though they do express bcl-6 [9] (Fig 27.3). A very useful marker is EMA (epithelial membrane antigen) which is often positive on at least a proportion

Typical LP cells

Typical low power pattern

FDCs

Large cell transformation

Fig 27.1 Nodular lymphocyte-predominant Hodgkin lymphoma: architecture and cytology. The diagnosis can frequently be made on low power examination. LP cells are usually easily detected at high power (top right) and are occasionally associated with multinucleated FDCs (bottom centre). Some cases show a large cell transformation (bottow right).

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Hodgkin Lymphoma

CD3

CD20

CD3

CD20

CD21

CDw75

EMA

Fig 27.2 Immunocytochemistry reveals the essential follicular nature of lymphocyte-predominant (LP) Hodgkin lymphoma with a strong FDC meshwork detected wit CD21. LP cells express B-cell associated antigens (e.g. CD20 and CDw75). Occasional cases show outstanding EMA positivity (bottom centre) but usually it is only weakly expressed on a subset of the LP cells. Cuffing by a collar of CD3 positive T lymphocytes around the LP cells is a characteristic feature.

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CD10

bcl6

κ

λ

κ of the LP cells [10]. Apart from plasma cells there are no EMA+ cells in reactive lymph nodes so this feature is helpful in making this distinction. LP cells may occasionally express CD30 (in particular on frozen sections) but they are negative for CD15 [10]. These should not be confused with the activated blast cells, which are often CD30+ but do not have any of the features of LP cells. Latent EBV infection is consistently

Hodgkin Lymphoma

Fig 27.3 In nodular lymphocyte-predominant (LP) Hodgkin lymphoma the LP cells are positive for bcl-6 but negative for CD10. They are usually also clonal for κ light chains.

λ

absent from LP cells (LMP1−, EBER−), but may be present in bystander lymphocytes (EBER+, LMP1−) sometimes known as reservoir lymphocytes (Table 27.1).

Genetics Given the small number of abnormal cells it has been difficult to obtain reliable genetic evidence to support the

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Hodgkin Lymphoma

Table 27.1 A comparison of the immunophenotype of classic Hodgkin lymphoma with lymphocyte-predominant Hodgkin lymphoma Marker

Classic Reed– Sternberg cells

Lymphocytepredominant cells

CD15 CD30 EMA CD20 CD79a CDw75 J chain CD45 BOB1/OCT2 Epstein–Barr virus

Usually + + Usually − Sometimes focally + Rarely + − − Usually − Usually − Frequently +

Usually − Rarely + Often + + + + + + + Usually −

immunostaining studies that this is a neoplasm of B cells. However, painstaking single cell microdissection experiments appear to have finally concluded that nodular LP Hodgkin lymphoma is a clonal proliferation of highly mutated germinal centre B cells [11,12].

Differential diagnosis There are three main areas of potential diagnostic difficulty concerning nodular LP Hodgkin lymphoma. These are reactive hyperplasias, large B-cell lymphoma and follicular lymphoma.

Reactive hyperplasia At times it can be difficult to distinguish nodular LP Hodgkin lymphoma from reactive nodes containing several progressively transformed germinal centres. This is compounded by the fact that patients with LP Hodgkin lymphoma have a tendency, in the course of the disease, to develop a reactive lymphadenopathy with the histological features of progressively transformed germinal centres. Usually the nodules in LP Hodgkin lymphoma replace the entire node, whereas they are only focal in reactive conditions. Furthermore, characteristic LP cells are not easily demonstrated in reactive conditions. Then finally the characteristic immunophenotype, especially the EMA positivity, is not seen in reactive conditions [13].

Large B-cell lymphoma A far more difficult differential diagnosis is with the rare large B-cell lymphoma variant T-cell/histiocyte-rich B-cell lymphoma (THRBCL). It is now considered that the presence of even one nodule excludes the diagnosis of

224

THRBCL, although what is or is not a nodule can lead to many interesting debates. Even so the diffuse T-cell-rich B-cell lymphomas are morphologically heterogeneous with one type (the ‘paragranuloma-like’ T-cell-rich B-cell lymphoma) consisting of a predominant population of small lymphocytes and scattered large cells showing an immunoblast-like morphology with resemblance to LP cells or Reed–Sternberg cells [14,15]. These large atypical cells are B lymphocytes strongly positive for CD20, CD75 and CD79, and may express EMA; a phenotype similar to LP Hodgkin lymphoma. Non-neoplastic small lymphocytes in the background are of T phenotype but in this case almost no CD57+ cells are present. Characteristically FDC meshworks are absent. At times when the number of polylobated B cells is high, this differential diagnosis may be impossible. Indeed it might well represent the borderline between LP Hodgkin lymphoma and large B-cell lymphoma into which a proportion of these cases transform with time. Large numbers of extranodular LP cells have been associated with the development of THRBCL and, for this reason, it is recommended that when cases of LP Hodgkin lymphoma relapse with THRBCL it is flagged as NLPHL, THRBCL like. Clinical features may help as LP Hodgkin lymphoma tends to occur as focal disease in young adults, whereas THRBCLs are more common in elderly people as disseminated disease with bone marrow involvement in more than 50% of cases.

Follicular lymphoma The neoplastic nodules are usually smaller than those of LP Hodgkin lymphoma but, on occasion, may include a few atypical LP-like cells. The floral variant of follicular lymphoma may show large nodules roughly comparable to those seen in LP Hodgkin lymphoma but they are composed of atypical cells that differ from LP cells, especially in being CD10+ (see Chapter 12).

Prognosis and treatment Nodular LP Hodgkin lymphoma pursues a much more indolent course than classic Hodgkin lymphoma, and long-term survival is common even without any treatment (an accepted form of treatment in many centres for stage 1 disease). This is despite the fact that it has a large growth fraction and a relatively high rate of late relapse, a paradox explained by the fact that these relapses usually respond well to therapy (Fig 27.4). As a result, different treatment protocols are now used for this type of Hodgkin lymphoma. There is a well-recognised tendency for diffuse large-cell non-Hodgkin lymphoma, usually of B-cell phenotype, to develop at some time during the course of the disease. This seems to occur more frequently than in other types of Hodgkin lymphoma and is assumed to represent transformation of the neoplastic LP cells (Fig 27.5).

CHAPTER 27

Hodgkin Lymphoma

CD20 Low power nodular histology with fibrosis

CD79a

Portfolio of LP cells

CD3 with EMA insert

Fig 27.4 Lymphocyte-predominant Hodgkin lymphomas are unusual in having such a propensity for late relapses but, when they occur, as shown here after 10 years of the disease, the appearance can be quite typical (note that patients can also have reactive nodes or higher-grade transformations).

Nodular sclerosis Hodgkin lymphoma This is the most common variant of classic Hodgkin lymphoma, accounting for more than half of all cases. Classic Hodgkin lymphoma is usually defined as different histological appearances of the typical binucleate or multinucleate Reed–Sternberg cell alongside mononuclear atypical cells (Hodgkin cells) in the appropriate inflammatory background [16].

Clinical features This variant is most common in adolescents and young adults, but can occur at any age; females equal or exceed males. The mediastinum is commonly involved and the stage and bulk of disease have prognostic importance.

Histology The tumour has a thickened capsule with at least a partially nodular pattern, with fibrous bands separating the nodules in most cases. Diffuse areas are common, as is necrosis. Characteristically some of the abnormal Reed–Sternberg or Hodgkin cells are fragile and break up to form a cell, looking like a lake with an island in its middle – the so-called ‘lacunar cell’. This was one of the original defining characteristics of nodular sclerosis in the Rye classification but it is a fixation artefact. With good modern fixation and processing the cells do not break up as they used to. The background contains lymphocytes, histiocytes, plasma cells, eosinophils and neutrophils. Some cases of nodular sclerosis may show large aggregates of lacunar cells (sometimes referred to as the syncytial variant) which may undergo central necrosis rich in granulocytes mimicking microabscesses (Fig 27.6).

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Hodgkin Lymphoma

Large B cell transformation in the small bowel

CD79a

CD20

Persistent lymphocyte predominant in the mesentery Fig 27.5 Here is a relapse after 20 years in the same patient as in Fig 27.4. This time the tumour in the small bowel is a large B-cell lymphoma but in the mesentery there is a lymphoproliferation with all the features of lymphocyte predominant Hodgkin lymphoma.

Subclassification according to the number of atypical cells may be clinically relevant; several grading schemes exist, of which that described by the British National Lymphoma Investigation is most widely used. This divides nodular sclerosis into type I (80% of cases) and II (20%). The latter is said to have a poorer prognosis and is diagnosed by having a greater number of more pleomorphic cells than typical Hodgkin lymphoma. None of these grading systems is currently taken into account when deciding on therapy but they may have a value for research purposes (Fig 27.7).

Immunophenotype The tumour cells are typically positive for CD15 and CD30 (Fig 27.8).

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CD45 is normally negative on paraffin sections (but may be positive in frozen sections). The B-cell-associated proteins PAX-5 and MUM1 are usually positive, emphasising the B-cell nature of this disease and being helpful in diagnosis [17,18]. The transcription factors OCT2 and BOB1 are usually negative but very rarely expressed together (Fig 27.9). In many cases (about 40%) a proportion of the abnormal cells express CD20 and a few express CD79a, but it is rare that both are expressed together. Such heterogeneous expression of B-cell-associated antigens, some cells being positive and others clearly negative, seems to be a characteristic feature of classic Hodgkin lymphoma (Fig 27.10). In rare cases some cells express CD3, usually with an abnormal dot-like cytoplasmic pattern (Fig 27.11).

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Hodgkin Lymphoma

Nodules and fibrosis

Nodules and fibrosis

Classic cytology

Syncytial variant

Multinucleated variant

Fig 27.6 This figure illustrates the range of architectural and cytological features that can be seen in nodular sclerosis Hodgkin lymphoma.

EMA is negative in most cases. CD15 and CD30 may be difficult to detect in paraffin sections in some cases and a range of antigen-retrieval techniques using microwaves or pressure cookers may be needed to achieve satisfactory results (Fig 27.12). In some cases CD15 and even CD30 staining may be restricted to the Golgi area on only a proportion of the neoplastic cells and require careful examination to be detected. In most cases of nodular sclerosis a number of neoplastic cells can usually be found encased within the FDC meshworks which can be a helpful feature in confirming the diagnosis. As a result of the ease with which Hodgkin lymphoma can be confused with other lesions we recommend a comprehensive immunophenotyping in all cases. However, this should not be at the expense of careful morphological examination because the diagnosis still depends importantly on

the correct histological features with immunophenotyping studies constituting the final confirmation (Table 27.2).

Genetics Molecular studies of the immunoglobulin and T-cell receptor genes have been difficult because of the small numbers of abnormal cells mixed up with reactive inflammatory cells of both B- and T-cell type. Careful single cell dissection techniques have revealed that many cases of Hodgkin lymphoma are of B cell origin [19,20] and a few of probable T-cell origin [21,22]. The number of cases studied is still too low to generalise these findings to all cases. Indeed other studies have demonstrated that Hodgkin cells possess a number of antigens (CD21, CNA.42, fascin) related to FDCs [23,24]. However, it is known that EBV can induce some of these antigens in B cells which may explain these findings as there

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Fig 27.7 Grading is rather subjective with the higher grade II being given to those cases with larger numbers of more ‘abnormal’ abnormal cells. The bottom two pictures show in the same case how fixation affects the delicate abnormal cells in Hodgkin lymphoma (fixed here in two different fixatives but delay in fixation and differences in processing are equally effective).

Grade I

Grade II

Bouin

Formalin

CD30

Fig 27.8 Examples of the types of staining for CD30 and CD15 seen in nodular sclerosing Hodgkin lymphoma.

228

CD15

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Hodgkin Lymphoma

BOB1

MUM1

is detectable EBV in about 50% of cases of classic Hodgkin lymphoma [25,26].

Differential diagnosis Hodgkin lymphoma, because of its mixed cellular make-up, can masquerade as many different lymphoma entities, especially the high-grade B- and T-cell lymphomas where fibrosis can be associated and anaplastic large-cell lymphoma (Fig 27.13). It should also be considered in the differential diagnosis of many different reactive entities because partial involvement of a lymph node can go unnoticed whereas the remaining node is hyperplastic. In particular Hodgkin lymphoma can elicit a profound granulomatous reaction and be

Fig 27.9 An example of the rare expression of the transcription factor BOB1 in classic Hodgkin lymphoma, with the much more commonly expressed B-cell-associated marker MUM1 below. Note that both markers are expressed widely on surrounding reactive cells, so careful examination is required to assess positivity on Reed–Sternberg cells.

mistaken for a number of infective conditions such as tuberculosis (Fig 27.14). Cases of nodular sclerosis with large aggregates of lacunar cells may be misdiagnosed as metastatic malignancy. Finally, occasional cases have extensive areas of necrosis rich in granulocytes which may suggest a misleading diagnosis of an infectious lesion. The key to its recognition is for the pathologist to consider it in any unusual lesions and to proceed to a full immunophenotyping to confirm or refute its presence.

Prognosis and treatment Hodgkin lymphoma was one of the first lymphomas to show a good response to multiple chemotherapy. There are now

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CD20

CD79a

CD21

CNA.42

Fascin

EBER

Fig 27.10 A number of lineage markers may be seen in Hodgkin lymphoma but the most common is CD20, often when other B-cell markers are negative such as CD79a illustrated here. Markers of dendritic cells such as CD21, CNA.42 and fascin are commonly positive. EB virus infection is found in 10–20% of nodular sclerosis as detected by EBER in situ.

several clinical series showing prolonged survival rates of more than 20 years of 80% or better. Staging alongside other clinical parameters still remains very important in predicting long-term outcome, although with the decline of staging laparotomies the role of the pathologist in this has somewhat declined.

Clinical features Mixed cellularity is more common in elderly people and the HIV-infected population and males outnumber females. Its stage may be more advanced than nodular sclerosis or LP types, involving lymph nodes, spleen, liver, or marrow. The course is moderately aggressive, but often curable.

Morphological features

Mixed cellularity Hodgkin lymphoma This variant was originally defined as those cases of definite Hodgkin lymphoma that would not fit into any other category. However, with time it has grown into its own identity as a true subtype of classic Hodgkin lymphoma.

230

The infiltrate is diffuse or vaguely nodular, without band-forming sclerosis or a particularly thickened capsule although fine interstitial fibrosis may be present. The disease is typically paracortical that is often best highlighted by immunostaining. RS cells are of the classic type and although by definition lacunar cells should be absent in fact a small

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Hodgkin Lymphoma

CD30

Histology

CD20

EMA

CD3

Fig 27.11 The more one immunostains neoplasms the more one finds the unexpected. Here a case of otherwise unremarkable nodular sclerosis has positivity for EMA, CD20 and on some cells CD3. CD3 positivity is rare in Reed-Sternberg cells but when present is usually cytoplasmic (inset bottom right) rather than membranous.

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EMA

CD30

CD15

Fig 27.12 Epithelial membrane antigen (EMA) is usually absent in classic Hodgkin lymphoma, making a useful distinction with anaplastic large-cell lymphoma. However, on occasion, when everything else points to Hodgkin lymphoma as in this case, EMA can be, as shown above, positive although weaker than in ALCL.

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number may be seen. As mentioned above these are really only a technical artefact of delicate cells stretched in a web of fibrosis (Fig 27.15).

Hodgkin Lymphoma

antigen profile in both types (LMP+ EBNA-1+ EBNA-2−). This latter may help in the distinction from some EBVpositive large B-cell lymphomas with Reed–Sternberg-like cells as these are usually EBNA-2+ (Fig 27.17).

Immunophenotype This is identical to nodular sclerosis Hodgkin lymphoma (Fig 27.16). EBV detection is more common in mixed cellularity (50– 70%) than nodular sclerosis (10–30%) with a characteristic

Table 27.2 The immunophenotype of the abnormal cells in 187 cases of classic Hodgkin lymphoma from one of the authors’ institutions (GD) Number of cases

Percentage

CD15

CD30

EMA

142 24 10 6 3 2

76 13 5 3 2 1

+ − + − + −

+ + + + − −

− − + + − −

Lymphocyte-rich Hodgkin lymphoma This is generally a nodular tumour with relatively infrequent Reed–Sternberg cells, which are of the classic type, rather than the variants seen in nodular LP Hodgkin lymphoma; some lacunar cells may be present, in a background of lymphocytes, with infrequent eosinophils or plasma cells. There is a rare diffuse variant that has a morphological overlap with diffuse LP Hodgkin lymphoma, the cellular phase of nodular sclerosis and mixed cellularity. In contrast to diffuse LP Hodgkin lymphoma, the Reed–Sternberg cells have the morphology and immunophenotype of classic Reed– Sternberg cells. The immunophenotype, genetic features and clinical features are similar to nodular sclerosis and mixed cellularity Hodgkin lymphoma. In the more common nodular form the presence of classic Reed–Sternberg cells with the CD15/CD-30+ immunophenotype will prevent misdiagnosis as nodular LP Hodgkin lymphoma. The nodules

Histology at different powers plus CD15 immunostaining

Fig 27.13 Cases such as this sit in a twilight zone between Hodgkin lymphoma and anaplastic large-cell lymphoma. This one has the architecture of nodular sclerosis, a cytology between the two conditions and the immunophenotype of Hodgkin lymphoma.

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Low power histology

Hodgkin cells

Granulomas

CD15

Necrosis

CD30

CD68

Fig 27.14 This case was diagnosed as probable tuberculosis but was negative on microbiological testing and did not quite fit clinically. Careful review and immunostaining revealed its true nature as Hodgkin lymphoma, granulomatous variant. This case does not easily slot into any category unless one uses mixed cellularity as the final resting ground of all unaccountable cases of Hodgkin lymphoma.

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Paracortical infiltration

Low to high power histology Apoptotic cells

Mummified cells

Classic Reed-sternberg cells

Fig 27.15 Mixed cellularity was originally the dustbin category of the Rye classification, but it has now reached an identity of its own as a paracortical infiltration with a mixed inflammatory infiltrate, numerous abnormal cells and in some cases apoptosis is frequent.

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CD30

CD15

CD20 positive

CD20 negative

CD3 Fig 27.16 Most cases of mixed cellularity are CD15+ and CD30+ with a substantial number also expressing CD20 on at least a proportion of the abnormal cells. Occasional cases show CD3 positivity usually as cytoplasmic dots (left) but occasionally with membrane staining (right).

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are mainly composed of expanded mantle zones surrounding small residual eccentrically placed germinal centres (Fig 27.18). In a multicentre study, 426 cases initially diagnosed as LP Hodgkin lymphoma were reclassified as LP Hodgkin lymphoma (51%), lymphocyte-rich classic Hodgkin lymphoma (27%), classic Hodgkin lymphoma (5%) non-Hodgkin lymphoma (3%) and reactive lesions (3%); 11% of cases were not classifiable [27].

Lymphocyte-depletion Hodgkin lymphoma This is the least common variant of Hodgkin lymphoma and has been steadily declining in numbers as immunophenotyping studies assign most cases to the B- or T-cell lineage of non-Hodgkin lymphomas especially ALCLs.

Clinical features It is seen more commonly in HIV-infected individuals and in developing countries and so may reflect the impact of a compromised immune system with classic Hodgkin lymphoma. It presents with abdominal and extranodal disease rather than with peripheral lymphadenopathy. The stage is usually advanced at diagnosis, although the response to treatment is reported not to differ from other subtypes at similar stages. LMP immunostaining

Morphological features The infiltrate is diffuse and often appears hypocellular, due to the presence of diffuse fibrosis and necrosis with only a few Reed–Sternberg cells. In other cases there are large numbers of Reed–Sternberg cells, often responsible for bizarre ‘sarcomatous’ variants, with a paucity of other inflammatory cells. The distinction with ALCL is difficult. Most pathologists rely heavily on immunophenotype at this stage and only diagnose lymphocyte depletion with a perfect classic Hodgkin lymphoma immunophenotype without any evidence of B- or T-cell lineage (Fig 27.19).

Extranodal involvement EBER Fig 27.17 Epstein–Barr virus (EBV) can be detected in many cases by immunostaining or in situ hybridisation (EBER or EBV RNA).

Bone marrow and/or liver biopsies are frequently performed in patients with Hodgkin lymphoma especially for staging purposes. Possibly because of the small sample size diagnostic Reed–Sternberg cells are rarely found, even with multiple serial sections. In this situation atypical cells expressing CD30 and CD15 antigens in a characteristic cellular background (often with fibrosis in the bone marrow) are generally accepted nowadays as evidence of involvement by Hodgkin lymphoma.

Differential diagnosis The histopathological diagnosis of Hodgkin lymphoma is sometimes considered to be an easy task for the general

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surgical pathologist. In fact mistaken diagnoses of Hodgkin lymphoma when it is not and something else when it is occurs commonly even today. For this reason we believe that it is clinically important to immunophenotype all cases of Hodgkin lymphoma. The expense of a few antibodies is far outweighed by that of a significant mistake. Probably the largest areas of difficulty are those lesions that contain Reed– Sternberg (like) cells but are not Hodgkin lymphoma. These include benign lymphadenopathies, carcinoma, melanoma, some soft-tissue tumours such as inflammatory malignant histiocytofibroma and some non-Hodgkin lymphomas (Fig 27.20).

Reed–Sternberg (like) cells in reactive lesions It is now well known that atypical immunoblasts simulating Reed–Sternberg cells can be found in a variety of forms of lymphadenitis, although absolutely perfect examples are mainly restricted to infectious mononucleosis. These immunoblasts are CD30+, CD15− and mostly strongly positive for all B-cell antigens including CD20 and CD79a. In addition, they are positive for EBV-LMP but negative for EBNA2.

Histology

T-cell/histiocyte-rich B-cell lymphomas These can mimic lymphocyte-rich classic Hodgkin lymphoma but the phenotype of the malignant cells is different as described previously (see Chapter 14).

Diffuse large B-cell lymphomas Tumours with an anaplastic morphology and rich in Reed– Sternberg cells may be confused with the sarcomatous variant of lymphocyte depletion Hodgkin lymphoma. Although these tumours can express CD30; the strong expression of CD20, CDw75 and CD79a makes a clear distinction from Hodgkin lymphoma.

HE

CD30

CD30 Fig 27.19 On review most cases with these appearances have been redesignated to other categories, mostly as anaplastic large-cell lymphoma, but a few, as above, meet the cytological and immunophenotypical criteria for lymphocyte-depletion Hodgkin lymphoma.

CD30

CD15

Fig 27.18 The most common type of lymphocyte-rich Hodgkin lymphoma consists of nodules composed of expanded mantle zones surrounding small eccentrically placed germinal centres. Within the mantle zones are scattered Reed–Sternberg cells which are best appreciated by staining for CD30 (shown at low and high power) and CD15.

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Infectious mononucleosis

Malignant Fibrous Histiocytoma (MFH)

T-cell lymphoma

EBV+ B-cell lymphoma in the thyroid

Carcinoma

B-cell lymphoma

Hodgkin Lymphoma

Fig 27.20 Reed–Sternberg-like cells can be seen in a variety of conditions as illustrated here. MFH, malignant fibrous histiocytoma.

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Table 27.3 Anaplastic large cell lymphoma Hodgkin-like (ALCL-HL) and Hodgkin lymphoma (HL): distinctive phenotypic criteria Phenotype

ALCL-HL

HL

CD30 CD15 EMA CD43 BNH-9 CD3 CD20 CD79a PAX5 CD21 (follicular dendritic cells) EBER EBV ALK

+ −/+ (<2%) ± (>80%) ± (>80%) + (60 %) ± − − − − − − ±

+ ± (>80%) ± (<5%) −/+ (<5%) − (5%) − −/+ − + + + + −

Peripheral T-cell lymphomas In particular the lymphoepithelioid variants (Lennert) may show Reed–Sternberg-like cells positive for CD30 and more rarely for CD15. Of diagnostic value is the T-cell (usually CD4+) phenotype of both the large and the small cells. In some instances, gene rearrangement studies may be required for a confident distinction.

Anaplastic large-cell lymphoma Nodular sclerosing and lymphocyte depletion Hodgkin lymphoma may be difficult to differentiate from the so-called Hodgkin-like ALCL. The most useful criteria are summarised in Table 27.3. The best marker is ALK protein expression which is found in up to 85% of ALCLs [28]. In ALK-negative tumours, CD15 and EMA are useful in differentiating Hodgkin lymphoma from ALCL as is the BNH.9 antibody, which recognises a glycosaccharidic antigen detectable on fixed biopsy specimens. Other criteria including EBV, T- and B-cell antigens, and FDCs are listed.

References 1. Harris NL, Jaffe ES, Stein H, et al. A revised European-American classification of lymphoid neoplasms: a proposal from the International Lymphoma Study Group [see comments]. Blood 1994;84:1361–92. 2. Jaffe ES, Harris NL, Stein H, Vardiman JW, eds. Pathology and Genetics of Tumours of Haematopoietic and Lymphoid Tissues. Lyon: IARC Press, 2001. 3. Swerdlow SH, Campo E, Harris NL, et al., eds. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 4th edn. Lyon: IARC Press, 2008. 4. Isaacson PG. The current status of lymphoma classification. Br J Haematol 2000;109:258–66.

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5. Mason D, Banks P, Chan J, et al. Nodular lymphocyte predominance Hodgkin’s disease: a distinct clinico-pathological entity. Am J Surg Pathol 1994;18:528–30. 6. Chittal SM, Alard C, Rossi JF, et al. Further phenotypic evidence that nodular, lymphocyte-predominant Hodgkin lymphoma is a large B-cell lymphoma in evolution. Am J Surg Pathol 1990;14:1024–35. 7. Banks P. Morphologic, immunologic and genetic features of lymphocyte predominance Hodgkin’s Disease. In: Mason D, Harris N (eds), Human Lymphoma: Clinical implications of the REAL classification. London: Springer, 1999. 8. Schmid C, Sargent C, Isaacson PG. L and H cells of nodular lymphocyte predominant Hodgkin’s disease show immunoglobulin light-chain restriction. Am J Pathol 1991;139:1281–9. 9. Dogan A, Bagdi E, Munson P, Isaacson PG. CD10 and BCL-6 expression in paraffin sections of normal lymphoid tissue and B-cell lymphomas. Am J Surg Pathol 2000;24:846–52. 10. Chittal S, Caveriviere P, Schwarting R, et al. Monoclonal antibodies in the diagnosis of Hodgkin’s disease. The search for a rational panel. Am J Surg Pathol 1988;12:9–21. 11. Marafioti T, Hummel M, Anagnostopoulos I, et al. Origin of nodular lymphocyte-predominant Hodgkin lymphoma from a clonal expansion of highly mutated germinal-center B cells [see comments]. N Engl J Med 1997;337:453–8. 12. Braeuninger A, Kuppers R, Strickler JG, Wacker HH, Rajewsky K, Hansmann ML. Hodgkin and Reed–Sternberg cells in lymphocyte predominant Hodgkin disease represent clonal populations of germinal center-derived tumor B cells [published erratum appears in Proc Natl Acad Sci U S A 1997;94:14211]. Proc Natl Acad Sci U S A 1997;94:9337–42. 13. Burns B, Colby T, Dorfman R. Differential diagnostic features of nodular L&H Hodgkin’s disease, including progressive transformation of germinal centers. Am J Surg Pathol 1984; 8:253–61. 14. Chittal S, Brousset P, Voigt J, Delsol G. Large B-cell lymphoma rich in T-cells and simulating Hodgkin’s disease. Histopathology 1991;19:211–20. 15. Delabie J, Vandenberghe E, Kennes C, et al. Histiocyte-rich B-cell lymphoma. A distinct clinicopathologic entity possibly related to lymphocyte predominant Hodgkin’s disease, paragranuloma subtype. Am J Surg Pathol 1992;16:37–48. 16. Banks P. Morphologic, immunologic and genetic features of ‘classical’ Hodgkin’s disease. In: Mason D, Harris N (eds), Human Lymphoma: Clinical implications of the REAL classification. London: Springer, 1999. 17. Foss HD, Reusch R, Demel G, et al. Frequent expression of the B-cell-specific activator protein in Reed–Sternberg cells of classical Hodgkin’s disease provides further evidence for its B-cell origin. Blood 1999;94:3108–13. 18. Carbone A, Gloghini A, Aldinucci D, Gattei V, Dalla-Favera R, Gaidano G. Expression pattern of MUM1/IRF4 in the spectrum of pathology of Hodgkin’s disease. Br J Haematol 2002;117: 366–72. 19. Marafioti T, Hummel M, Foss HD, et al. Hodgkin and Reed– Sternberg cells represent an expansion of a single clone originating from a germinal center B-cell with functional immunoglobulin gene rearrangements but defective immunoglobulin transcription. Blood 2000;95:1443–50.

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20. Kuppers R, Rajewsky K, Zhao M, et al. Hodgkin disease: Hodgkin and Reed–Sternberg cells picked from histological sections show clonal immunoglobulin gene rearrangements and appear to be derived from B cells at various stages of development. Proc Natl Acad Sci U S A 1994;91:10962–6. 21. Seitz V, Hummel M, Marafioti T, Anagnostopoulos I, Assaf C, Stein H. Detection of clonal T-cell receptor gamma-chain gene rearrangements in Reed–Sternberg cells of classic Hodgkin disease. Blood 2000;95:3020–4. 22. Muschen M, Rajewsky K, Brauninger A, et al. Rare occurrence of classical Hodgkin lymphoma as a T cell lymphoma [in process citation]. J Exp Med 2000;191:387–94. 23. Delsol G, Meggetto F, Brousset P, et al. Relation of follicular dendritic reticulum cells to Reed–Sternberg cells of Hodgkin lymphoma with emphasis on the expression of CD21 antigen. Am J Pathol 1993;142:1729–38. 24. Raymond I, Al Saati T, Tkaczuk J, Chittal S, Delsol G. CNA.42, a new monoclonal antibody directed against a fixative-resistant antigen of follicular dendritic reticulum cells. Am J Pathol 1997;151:1577–85.

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25. Nakamura S, Nagahama M, Kagami Y, et al. Hodgkin Lymphoma expressing follicular dendritic cell marker CD21 without any other B-cell marker: a clinicopathologic study of nine cases. Am J Surg Pathol 1999;23:363–76. 26. Pinkus GS, Pinkus JL, Langhoff E, et al. Fascin, a sensitive new marker for Reed–Sternberg cells of Hodgkin’s disease. Evidence for a dendritic or B cell derivation? Am J Pathol 1997;150: 543–62. 27. Diehl V, Sextro M, Franklin J, et al. Clinical presentation, course, and prognostic factors in lymphocyte-predominant Hodgkin lymphoma and lymphocyte-rich classical Hodgkin’s disease: report from the European Task Force on Lymphoma Project on Lymphocyte-Predominant Hodgkin’s Disease. J Clin Oncol 1999;17:776–83. 28. Benharroch D, Meguerian-Bedoyan Z, Lamant L, et al. ALKpositive lymphoma: a single disease with a broad spectrum of morphology. Blood 1998;91:2076–84.

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Immunodeficiency-associated Lymphoproliferative Disorders

Apart from areas with a high incidence of HIV infection (partially dealt with earlier in this text) these disorders are mainly related to chronic immunosuppression especially post-transplantation or to congenital and acquired immune deficiency syndromes. These are uncommon which accounts for the difficulties in making substantive statements about lymphoid lesions in them.

Post-transplantation An increased incidence of lymphomas far in excess of the general population was noted early on in the follow-up of organ transplant recipients. Almost immediately a confusion arose as to whether or not they were lymphomas because they were associated with Epstein–Barr virus (EBV) and some remarkable regressions occurred with reductions in immunosuppression. They are now almost universally referred to as post-transplantation lymphoproliferative disorders or PTLDs, which are defined as lymphoid proliferations occurring in immunosuppressed organ transplant recipients. They are usually associated with EBV infection, although increasing numbers of EBV-negative cases are being reported [1]. PTLDs may occur at almost any time from a month or so after transplantation up to several years. The risk is lowest for renal and bone marrow recipients (about 1%), rising through liver and heart (2%) to heart– lung/intestinal (4–5%). The major risk factors seem to be age (children and older adults) and recipients with negative EBV serology at time of engraftment [2,3]. The type of immunosuppression is important with ciclosporin and monoclonal antibody T-cell depletion having the highest risks [4].

Pathology Virtually all PTLDs are B-cell proliferations with a substantial majority arising extranodally in sites such as skin, soft tissue, gut and lung, with only occasional cases in the central nervous system. Involvement of the graft itself (apart from the heart) is also relatively common. The histological features cover a spectrum of lymphoid lesions, often with quite different focal areas in the same patient. This has led to great difficulty in accommodating PTLDs into conventional lymphoid classifications and to schemes dedicated to PTLDs alone. The two best known are the Pittsburgh (polymorphous and monomorphous PTLD) [5] and Minnesota (plasmacytic hyperplasia, polymorphous hyperplasia, polymorphous lymphoma, immunoblastic lymphoma/myeloma) classifications [6]. Both essentially reflect the spectrum from benign polyclonal reactive change to a full-blown disseminated aggressive lymphoma. The World Health Organization (WHO) committee deliberations on this area recommended keeping a separate system for PTLDs but not other immunodeficiency-associated lymphomas because of their distinctive biological and clinical features [7]. This has been refined in the 2008 WHO classification as: 1. Early lesions: plasmacytic hyperplasia infectious mononucleosis (IM)-like lesion 2. PTLD – polymorphic (most also being polyclonal) 3. PTLD – monomorphic (clonal lesions which can also be further classified according to the WHO lymphoma classification as B- or T-cell lymphomas) 4. Classic Hodgkin lymphoma-type PTLD. In general group 3 is the most common by far, of which most lesions would be diagnosed as diffuse large B-cell lymphomas in the absence of any clinical knowledge.

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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CD20

Kappa

Lambda

EB virus LMP Fig 28.1 WHO early lesions are essentially reactive lesions associated with Epstein–Barr virus infection. This case from a tonsil is an infectious mononucleosis-like post-transplantation lymphoproliferative disorder (PTLD) in which κ and λ demonstrate polyclonal staining.

Immunophenotypically PTLDs are no different from the lymphomas or reactive lesions that they resemble except that they frequently have EBV which is usually easily detected immunocytochemically.

proliferation (Fig 28.1). Some cases show follicular hyperplasia although its relationship to PTLD is not yet defined [8]. These cases often regress with reduction of immunosuppression.

Early lesions

Polymorphic PTLD

These lesions occur more commonly in children and the tonsils are a common site of involvement. The ‘early’ refers to the changes in the lymphoid tissues that are architecturally intact and show predominantly paracortical expansion with a plasmacytic or mixed (IM-like) cellular

This is often a difficult category for diagnosis because the lymph node or tissue changes are generally destructive and atypical but do not resemble any recognisable lymphomalike lesion. They are composed of a range of lymphoid cell types of all sizes and maturity often with areas of necrosis.

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Immunodeficiency-associated Lymphoproliferative Disorders

HEs

κ

λ

Unusual large cells including Reed–Sternberg-like cells may be seen, although not in sufficient numbers or contexts to justify a diagnosis of lymphoma. These lesions are predominantly B cell and may show light chain restriction or IgH rearrangement (Fig 28.2). However, when they do the staining is usually only focal or the bands are small on a polyclonal background. Some cases may regress with reduction of immunosuppression although many progress to need lymphoma therapy [5].

Monomorphic PTLD For practical purposes this category comprises those PTLDs that satisfy the criteria for a diagnosis of diffuse large B-cell lymphoma, or less commonly Burkitt lymphoma and myeloma. The immunophenotypes are the same as those described earlier for their respective lymphoma types. Most but not all cases show evidence of EBV. DLBCL is the most common subtype by far and most of them are of nongerminal centre or activated phenotype (Figs 28.3 and 28.4). A few cases are of T- and/or natural killer (NK)-cell lineage. These can have the morphology and phenotype of any of the T-cell lymphomas described in the WHO classification, although the most common are best classified as peripheral T-cell lymphoma not otherwise specified (NOS). This group of PTLDs, being so uncommon, is generically referred to as monomorphic T-/NK-cell PTLD (Fig 28.5).

Classic Hodgkin lymphoma-type PTLD Although fiendishly rare these cases have been granted a subcategory of their own. As Hodgkin lymphoma-like features are so common in many PTLDs the WHO emphasise

244

EBV LMP

Fig 28.2 Three cases of polymorphic post-transplantation lymphoproliferative disorder (PTLD) showing the range of mixed cellularity that may be seen in this condition. Light chain staining may be either polyclonal as here or monoclonal. Evidence of Epstein–Barr virus positivity is usually present.

that to make this diagnosis the total morphology and phenotpye should be of textbook standard, and exceptions even extending to CD15 negativity need to be handled with caution (Fig 28.6).

Prognosis and treatment Most centres attempt to reduce or remove immunosuppression especially in the lymphomatous lesions. This of course is not easy with anything other than the renal cases, in whom an alternative treatment is available if the graft is rejected. Otherwise conventional lymphoma therapy is necessary to achieve remissions and survival [9]. Antiviral therapy has not been shown to be of any value. Overall the literature suggests that the prognosis is poor for PTLDs with a mortality rate of over 50%, showing that clinically these lesions are mainly high-grade lymphomas in an immunocompromised population.

Congenital and acquired immune deficiency syndromes Congenital syndromes There is an undoubted increase in reactive lymphoid lesions and lymphomas in patients with congenital and acquired immune deficiency syndromes. The congenital conditions are all rare and tend to gravitate towards specialist centres dealing with their therapy, so that ordinary cancer centres see few cases. The reactive conditions are often complicated by unusual superadded infections such as cytomegalovirus (Fig 28.7).

CHAPTER 28

Immunodeficiency-associated Lymphoproliferative Disorders

HE

HE

CD20

EBV LMP

EBNA 1

EBNA 2

Fig 28.3 Morphology of two typical monomorphic post-transplantation lymphoproliferative disorders (PTLDs) of DLBCL type. They are CD20+ and express the full EBV phenotype of LMP1 and EBNAs 1 and 2.

HE

HE

CD20

CD79a

κ

VS38

λ

EBV LMP

Fig 28.4 Monomorphic post-transplantation lymphoproliferative disorder (PTLD) of plasmacytoma/plasmablastic lymphoma type arising in the skin. The tumour is negative for B-cell antigens (CD20 and CD79a) but positive for VS38 and monotypic for κ light chains. EBV+ cells are present although not numerous.

245

HE

CD2

CD3

CD5

EBER

Fig 28.5 Monomorphic NK/T post-transplantation lymphoproliferative disorder (PTLD) showing the typical pleomorphic cytology of a peripheral T-cell non-Hodgkin lymphoma not otherwise specified (NHL NOS). The tumour is CD2+ CD3+ CD5− and EBER+ for EBV.

EBV LMP

CD30

CD20

Fig 28.6 Rarely other types of lymphoma are found in post-transplant recipients such as this example of Hodgkin lymphoma. T-cell lymphomas with a variety of morphologies have also been reported.

IgD

CD20

CD21

IgM

CMV

Fig 28.7 Example of a very abnormal follicular hyperplasia in a patient with common variable immune deficiency. The follicles are blurred together (CD20) with abnormal masses of follicular dendritic cells (CD21) and very small mantle zones (IgD), with virtual absence of IgM producing cells. Throughout the follicles there was evidence of cytomegaloviral infection.

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HE

Immunodeficiency-associated Lymphoproliferative Disorders

CD20

CD3

EBNA 1

Fig 28.8 Case of T/histiocyte-rich large B-cell lymphoma arising in a child with common variable immune deficiency. The features are identical to those seen in immunocompetent patients except that Epstein–Barr virus is present in most lymphomas associated with immune deficiency syndromes.

HE

CD20

CD30

EBV LMP

mib1

bcl2

Fig 28.9 Typical aggressive diffuse large B-cell lymphoma arising in the lip of an HIV-positive patient.

Disorders associated with an increased risk of lymphoma include common variable immune deficiency (CVID), ataxia telangiectasia, Bruton agammaglobulinaemia, severe combined immune deficiency (SCID), Wiskott–Aldrich syndrome and X-linked lymphoproliferative disorder. Most tumours arise in children and are B cell with diffuse large B-cell lymphoma (DLBCL) predominating. EBV is associated with most of these lesions (Fig 28.8). Follicular lesions, of which most are hyperplasias but some follicular lymphomas, are also common. Other types of lymphoma including T-cell and Hodgkin lymphomas are reported but rare. The key to diagnosis is careful morphological and immunocytochemical study and to classify the

lesions on this basis without regard to the underlying syndrome. Clinicians will of course take this into account and may well wish to incorporate immunological therapies such as immunoglobulin into their treatment regimen [10].

HIV-associated lymphomas Other than PTLDs the main source of acquired immune deficiency-related lymphoid lesions is in association with HIV infection. A variety of reactive lesions associated with HIV are dealt with in Chapter 2. The lymphomas seen in HIV patients are virtually always highly aggressive lesions, usually of B-cell type (Fig 28.9). They tend to arise more commonly in extranodal sites and are probably the most

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common cause of central nervous system lymphomas. The morphology and immunophenotype of HIV-associated lymphomas are exactly the same as for immunocompetent individuals, as described in earlier chapters. Some lymphomas are almost restricted to HIV positive individuals and include primary effusion lymphoma, plasmablastic lymphoma and lymphoma arising in HHV8- associated Castleman disease. The risk of lymphoma in HIV infection is more than a 100 times that of the normal population though the highly successful cocktail antiretroviral therapies have almost halved this in recent years. Modern anti HIV therapy has also considerably improved survival in those HIV patients who do succumb to lymphoma.

References 1. Leblond V, Davi F, Charlotte F, et al. Posttransplant lymphoproliferative disorders not associated with Epstein-Barr virus: a distinct entity? J Clin Oncol 1998;16:2052–9. 2. Caillard S, Lelong C, Pessione F, Moulin B. Post-transplant lymphoproliferative disorders occurring after renal transplantation in adults: report of 230 cases from the French Registry. Am J Transplant 2006;6:2735–42. 3. Webber SA, Naftel DC, Fricker FJ, et al. Lymphoproliferative disorders after paediatric heart transplantation: a multiinstitutional study. Lancet 2006;367:233–9.

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4. Ferry J, Harris N. Lymphoproliferative disorders following organ transplantation. Adv Pathol Lab Med 1994;7:359–87. 5. Nalesnik MA, Jaffe R, Starzl TE, et al. The pathology of posttransplant lymphoproliferative disorders occurring in the setting of cyclosporine A-prednisone immunosuppression. Am J Pathol 1988;133:173–92. 6. Frizzera G, Hanto DW, Gajl-Peczalska KJ, et al. Polymorphic diffuse B-cell hyperplasias and lymphomas in renal transplant recipients. Cancer Res 1981;41(11 Pt 1):4262–79. 7. Harris NL, Jaffe ES, Diebold J, et al. The World Health Organization classification of neoplastic diseases of the haematopoietic and lymphoid tissues: Report of the Clinical Advisory Committee Meeting, Airlie House, Virginia, November 1997. Histopathology 2000;36:69–86. 8. Vakiani E, Nandula SV, Subramaniyam S, et al. Cytogenetic analysis of B-cell posttransplant lymphoproliferations validates the World Health Organization classification and suggests inclusion of florid follicular hyperplasia as a precursor lesion. Hum Pathol 2007;38:315–25. 9. Praghakaran K, Wise B, Chen A, Schwarz K, Colombani P. Rational management of posttransplant lymphoproliferative disorder in pediatric recipients. J Pediatr Surg 1999;34:112–15; discussion 5–6. 10. Ferry J, Harris N. Atlas of Lymphoid Hyperplasia and Lymphoma. Philadelphia: WB Saunders, 1997.

29

Histiocytic Sarcoma

Histiocytic sarcoma (also known as true histiocytic lymphoma) accounts for less than 1% of adult non-Hodgkin lymphomas in the USA and Europe [1–4]. Most tumours classified in the past as histiocytic proliferations, such as histiocytic lymphoma [5], histiocytic medullary reticulosis, histiocytic reticulum cell sarcoma, malignant histiocytosis and regressing atypical histiocytosis, are now recognised as non-histiocytic in nature [6]. These tumours originate from lymphoid cells showing an anaplastic morphology expressing T- or more rarely B-cell antigens.

eccentric round or oval nuclei and usually abundant pale or slightly eosinophilic cytoplasm. Some other cases show a pronounced cellular pleomorphism with cells of varying size and shape exhibiting atypical nuclei. Multinucleated cells are commonly found in these cases. These cells show no evidence of phagocytosis and when present haemophagocytosis is more commonly observed in the admixed reactive histiocytes than in neoplastic ones. Neoplastic foamy cells have been reported in some cases [7] (Fig 29.1). Electron microscopy usually shows a variable number of lysosomes in the neoplastic cells.

Clinical features Blood involvement Histiocytic sarcoma occurs in either sex and patients show a wide age range. The clinical presentation is highly variable, although most patients present with extranodal tumours, especially single or multiple skin nodules sometimes associated with lymphadenopathy [3,7]. Extranodal involvement at diagnosis or during the course of the disease is common and includes bone marrow, spleen, liver, soft tissue, small intestine, meninges and lytic bone tumours [1,8,9]. Systemic symptoms are common. Occasional patients develop leukaemia with neoplastic cells in the blood a few months after diagnosis [1].

Histology In lymph node biopsy specimens the normal architecture is obliterated by a diffuse proliferation of large neoplastic cells. Some cases show a sinusoidal growth pattern with neoplastic cells admixed with reactive histiocytes. In the skin, the infiltrate involves the upper and lower dermis with no epidermotropism. The cytological features of the neoplastic cells are highly variable. Some cases consist of large mononuclear cells with

The presence of neoplastic cells in the peripheral blood at diagnosis is suggestive of a monocytic leukaemia with extranodal involvement rather than a true histiocytic sarcoma.

Immunophenotype Characteristically histiocytic sarcomas express several histiocytic markers, including CD68 (PGM1 is more specific than KP1 which also reacts with cells of the myeloid lineage), CD163, lysozyme and CD4 on paraffin, and CD11c and CD14 on frozen sections. In addition, they express the leukocyte common antigen CD45 and are usually positive for CD43, CD45RO and HLA-DR. Occasional cases are positive for S100 protein [7, 8], which may cause some confusion with Langerhans cell histiocytosis or interdigitating dendritic cell sarcoma, although negativity for CD1a should help resolve this. A further lack of reactivity of the neoplastic cells with B- and T-cell markers, myeloperoxidase, follicular dendritic cell-associated antigens (CD21, CD35, CNA-42), as well as epithelial and melanoma-associated antigens is also

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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CD68/PGM1

CD43

CD68/KP1

Proliferation

CD3

Fig 29.1 Typical histology and immunophenotype of a true histiocytic sarcoma. Of the histiocytic markers, PGM1 is the most specific, although KP1 often gives the strongest and most striking staining. Most cases are positive for CD43 but negative for CD3 and have a high proliferation rate (Ki67).

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Table 29.1 Phenotypes of histiocytic proliferations and haematopoietic neoplasms consisting of large cells Lymphoma type

CD1a

CD3

CD4

CD15

CD20

CD30

CD43

CD68

S100

Others

Histiocytic sarcoma

−

−

+

−a

−

−

+

+b

±

Langerhans cell histiocytosis Interdigitiating reticulum cell sarcoma Granulocytic sarcoma (AML) Anaplastic large-cell lymphoma Diffuse large B-cell lymphoma Peripheral T-cell lymphoma

+ − − − − −

− − − ± − +

+ − − ± − ±

− − + − −

− − − −

− − + ± ±

+ ± + + ± +

+ ± -b − − −

Lysozyme CD163 Langerin

+ − − − −

a

Myeloperoxidase ALK B-cell markers T-cell markers

Focal expression has been reported in rare cases [7,8]. CD68/PGM1 is a better marker that CD68/KP1 since the latter is also positive in myeloblastic proliferations (granulocytic sarcoma)

b

required for the diagnosis of a true histiocytic sarcoma. CD30 detected by the Ki-1 antibody may be expressed occasionally [10], although the specificity of such staining has been questioned because these cases are negative for CD30 with the more commonly used antibody Ber-H2 (Table 29.1).

morphological features. These include diffuse large B-cell lymphomas, peripheral T-cell lymphomas consisting of a predominant population of large cells and anaplastic largecell lymphoma. As shown in Table 29.1 these tumours can be easily distinguished using a simple panel of antibodies.

Other haematopoietic neoplasms

Cytogenetics No consistent chromosomal abnormalities have been described.

Prognosis and treatment The course is usually highly aggressive with a poor response to chemotherapy and a short survival (1–24 months) [1,6].

Differential diagnosis Non-lymphoid tumours Non-lymphoid tumours such as carcinomas and melanomas are not usually a problem because true histiocytic sarcomas are positive for CD45 ( the leukocyte common antigen) and unstained for epithelial and melanocytic antigens. A diagnostic pitfall worth mentioning is that melanomas (up to 80% in one study) may express CD68 especially with antibody KP1 [11].

B- and T-cell lymphomas Histiocytic sarcoma needs to be distinguished from a number of haematopoietic neoplasms which might show comparable

A number of other haematopoietic neoplasms may be confused with true histiocytic sarcoma because they can share a number of morphological and phenotypic features.

Langerhans cell histiocytosis This is usually recognised on the basis of its morphological features and expression of CD1a and S100 protein (see Chapter 31). However, occasional cases designated as Langerhans cell sarcoma showing cellular pleomorphism are more difficult to diagnose because of the dissociated expression or even the lack of Langerhans cell-associated antigens.

Interdigitating dendritic cell sarcoma It is difficult to make this diagnosis because of the lack of definite morphological and phenotypic criteria. Morphologically the tumour often resembles a follicular dendritic cell (FDC) sarcoma but does not express FDC antigens [12,13] (see below). Some other cases are morphologically indistinguishable from large B or T cell lymphoma or histiocytic sarcoma. Electron microscopy shows complex interdigitating cytoplasmic processes but Birbeck granules are lacking(14, 15]. Most cases are positive for S100 protein and vimentin, variably positive for CD68 and CD45 but negative for CD1a (7]. However, occasional cases have been positive for CD1a making the differential diagnosis with Langerhans cell histiocytosis difficult [14,15]. This tumour

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Fig 29.2 Blastic plasmacytoid dendritic cell (PDC) neoplasm in the skin. This shows a blastic morphology with the PDC immunophenotype of CD4+ CD56+ CD68+ bcl11a+ CD123+ TdT+ CD7+, but negative for CD3, CD163 and CD2. This is an aggressive tumour with a high proliferation rate (Ki67).

is aggressive in most but not all patients [16], although the scarcity of reported cases does not allow any definite conclusions to be drawn.

Cutaneous and/or lymph node involvement by monoblastic leukaemia Both skin and lymph node infiltration by leukaemic cells may precede the overt blood involvement. The phenotype is similar to that of histiocytic sarcoma although the frequent expression of CD34 in monoblastic leukaemia may turn out to be of diagnostic value [7].

Granulocytic sarcoma/acute myeloid leukaemia (see Chapter 32) Distinguishing myeloblastic proliferations from histiocytic sarcoma can be difficult especially in cases of extramedullary involvement. It is worth noting that myeloblastic proliferations are positive for CD68 (KP1 but usually not PGM1), CD4, CD43, CD45 and lysozyme. However, they are also positive for myeloperoxidase, elastase and CD34, which are typically not expressed by histiocytic sarcoma.

Blastic plasmacytoid dendritic cell neoplasm This rare haematopoietic neoplasm initially described under the name of ‘malignant lymphoma of plasmacytoid T-cells’

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[17] has had many other names in the past. It may be related to histiocytic sarcoma, although its origins are unclear. It is now classified with the myeloid lesions not the lymphomas by the WHO [18]. The morphological and phenotypic features of the malignant cells are similar to plasmacytoid monocytes, as seen in the paracortical area in some reactive lymph nodes [19,20]. These tumours tend to be extensive at presentation, with involvement of skin and bone marrow being particularly common [21]. Lymph nodes are affected in about half of the cases described. On superficial examination the tumour is reminiscent of lymphoblastic lymphoma because it consists of a relatively monotonous population of medium-sized cells showing round to oval nuclei with fine chromatin and small nucleoli and moderate amounts of cytoplasm. Some starry-sky macrophages can be observed. Mitoses are scarce. The neoplastic cells express CD4, CD43, CD45RA, CD56 and frequently CD7 and CD68 (KP1 and PGM1). All other T-cell markers, lysozyme, CD163 and myeloperoxidase are negative [22,23]. They are characterised by positivity for plasmacytoid dendritic cell-associated markers such as CD123, CD2AP and bcl-11a [24]. About 30% of cases express TdT (terminal dexynucleotide transferase) although both CD117 and CD34 are negative. This is an aggressive neoplasm with a short survival even if there is an initial good response to chemotherapy (Fig 29.2).

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Histiocytic Sarcoma

HE

HE

CD3

CD4

CD56

PGM1

bcl11a

CD123

TdT

CD2

CD7

CD163

mib1

Fig 29.2 continued. Blastic Plasmacytoid Dendritic cell neoplasm

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Benign accumulations of histiocytes These are seen in storage diseases such as Gaucher disease and Niemann–Pick disease and in some infections with Mycobacterium or Leishmania spp. and must not be mistaken for histiocytic sarcoma.

References 1. Ralfkiaer E, Delsol G, O’Connor NT, et al. Malignant lymphomas of true histiocytic origin. A clinical, histological, immunophenotypic and genotypic study. J Pathol 1990;160:9–17. 2. Soria C, Orradre JL, Garcia-Almagro D, Martinez B, Algara P, Piris MA. True histiocytic lymphoma (monocytic sarcoma). Am J Dermatopathol 1992;14:511–7. 3. Warnke R, Weiss L, Chan J, Cleary M, Dorfman R. Tumors of the Lymph Nodes and Spleen. Washington DC: Armed Forces Institute of Pathology, 1995. 4. Copie-Bergman C, Wotherspoon AC, Norton AJ, Diss TC, Isaacson PG. True histiocytic lymphoma: a morphologic, immunohistochemical, and molecular genetic study of 13 cases. Am J Surg Pathol 1998;22:1386–92. 5. Vose JM, Armitage JO. Diffuse ‘histiocytic’ lymphoma. Semin Oncol 1991;18:50–60. 6. Wilson MS, Weiss LM, Gatter KC, Mason DY, Dorfman RF, Warnke RA. Malignant histiocytosis. A reassessment of cases previously reported in 1975 based on paraffin section immunophenotyping studies. Cancer 1990;66:530–6. 7. Pileri SA, Grogan TM, Harris NL, et al. Tumours of histiocytes and accessory dendritic cells: an immunohistochemical approach to classification from the International Lymphoma Study Group based on 61 cases. Histopathology 2002;41:1–29. 8. Kamel OW, Gocke CD, Kell DL, Cleary ML, Warnke RA. True histiocytic lymphoma: a study of 12 cases based on current definition. Leuk Lymphoma 1995;18(1–2):81–6. 9. Franchino C, Reich C, Distenfeld A, Ubriaco A, Knowles DM. A clinicopathologically distinctive primary splenic histiocytic neoplasm. Demonstration of its histiocyte derivation by immunophenotypic and molecular genetic analysis. Am J Surg Pathol 1988;12:398–404. 10. Andreesen R, Brugger W, Lohr GW, Bross KJ. Human macrophages can express the Hodgkin’s cell-associated antigen Ki-1 (CD30). Am J Pathol 1989;134:187–92. 11. Pernick NL, DaSilva M, Gangi MD, Crissman J, Adsay V. ‘Histiocytic markers’ in melanoma. Mod Pathol 1999;12: 1072–7.

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12. van den Oord JJ, de Wolf-Peeters C, de Vos R, Thomas J, Desmet VJ. Sarcoma arising from interdigitating reticulum cells: report of a case, studied with light and electron microscopy, and enzymeand immunohistochemistry. Histopathology 1986;10:509–23. 13. Liu SM, Huang PH, Liu JM. Interdigitating reticulum cell tumor of lymph node: a case report and literature review. Pathol Int 1998;48:974–80. 14. Chan WC, Zaatari G. Lymph node interdigitating reticulum cell sarcoma. Am J Clin Pathol 1986;85:739–44. 15. Yamakawa M, Matsuda M, Imai Y, Arai S, Harada K, Sato T. Lymph node interdigitating cell sarcoma. A case report. Am J Clin Pathol 1992;97:139–46. 16. Nakamura S, Koshikawa T, Kitoh K, et al. Interdigitating cell sarcoma: a morphologic and immunologic study of lymph node lesions in four cases. Pathol Int 1994;44:374–86. 17. Muller-Hermelink H, Steinmann G, Stein H, Lennert K. Malignant lymphoma of plasmacytoid T cells. Morphologic and immunologic studies characterizing a special type of T cell. Am J Surg Pathol 1983;7:849–62. 18. Swerdlow SH, Campo E, Harris NL, et al., eds. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. 4th edn. Lyon: IARC Press, 2008. 19. Facchetti F, deWolf-Peters C, Mason D, Pulford K, vanden Oord DV. Plasmacytoid T cells: immunohistochemical evidence for their monocyte/macrophage origin. Am J Pathol 1988;133:15–21. 20. Thomas JO, Beiske K, Hann I, Koo C, Mason DY. Immunohistological diagnosis of ‘pasmacytoid T cell lymphoma’ in paraffin wax sections. J Clin Pathol 1991;44:632–5. 21. Petrella T, Dalac S, Maynadié M, et al. CD4+ CD56+ cutaneous neoplasms: A distinct hematological entity? Am J Surg Pathol 1999;23:137–46. 22. Petrella T, Bagot M, Willemze R, et al. Blastic NK-cell lymphomas (agranular CD4+CD56+ hematodermic neoplasms): a review. Am J Clin Pathol 2005;123:662–75. 23. Nguyen TT, Schwartz EJ, West RB, Warnke RA, Arber DA, Natkunam Y. Expression of CD163 (hemoglobin scavenger receptor) in normal tissues, lymphomas, carcinomas, and sarcomas is largely restricted to the monocyte/macrophage lineage. Am J Surg Pathol 2005;29:617–24. 24. Marafioti T, Paterson JC, Ballabio E, et al. Novel markers of normal and neoplastic human plasmacytoid dendritic cells. Blood 2008;111:3778–92.

30

Follicular Dendritic Cell Proliferations and Related Entities

Follicular dendritic cell (FDC) sarcoma was first described by Monda and coworkers in 1986 [1]. This relatively rare tumour has distinctive morphological and phenotypic features [2]. Since its original description, some reports have suggested that the morphological features of FDC proliferations are more diverse than thought initially [2,3]. Lymph nodes are the most common sites of these tumours although it is now recognised that they may occur in extranodal sites. Besides the FDC sarcoma [1], it has been shown that some inflammatory pseudotumours develop from FDCs and are associated with Epstein–Barr virus (EBV) [3–5]. Association of FDC tumours with hyaline–vascular Castleman disease has also been reported [2].

Clinical presentation and follow-up FDC proliferations occur mainly in adults who, most commonly, present with neck soft-tissue masses or, more rarely, mediastinal or retroperitoneal tumours. Some tumours involve the small intestine and the mesentery, and are responsible for a misdiagnosis of metastatic carcinoma. Liver and spleen tumours developing from FDCs correspond usually to so-called ‘inflammatory pseudotumours’ [4,5]. Although the course of the disease seems to be quite variable after surgical resection (sometimes followed by chemotherapy and radiotherapy) most patients are in complete remission 5 years after the treatment [6]. Late relapses (more than 15 years after diagnosis) with local recurrence and occurrence of metastasis have been recorded [7]. The behaviour of FDC tumours is difficult to predict on morphological grounds [2]. However an abdominal location, areas of necrosis, high numbers of mitoses and cellular atypia seem to be adverse prognostic factors [2]. It should be noted that many reports on these tumours have a relatively short follow-up and may not accurately depict their natural history.

Histology FDC proliferations show a broad spectrum of morphological features and can be classified into six categories.

FDC sarcoma Characteristically, these tumours consist of spindle cells with scant cytoplasm and oval vesicular nuclei with distinct nucleoli. In all cases, binucleated cells reminiscent of normal FDCs are present (Fig 30.1). Multinucleated giant cells are also found in all cases. However, the growth pattern varies from case to case, the most characteristic pattern consisting of intersecting fascicles of spindle cells. Some cases show areas with jigsaw-puzzle-like lobulation or a meningiomalike pattern. Occasional cases show fascicular areas associated with diffuse, patternless areas with syncytial looking cells with plump atypical nuclei and scattered lymphocytes. All these tumours are sprinkled with small lymphocytes mainly of T-cell phenotype. Sheets of plasma cells are often found in liver tumours but are unusual elsewhere. Necrotic areas rich in granulocytes can also be observed.

FDC sarcoma associated with Castleman disease Rare cases of typical FDC sarcoma associated with features of Castleman tumour have been described. FDC sarcoma and Castleman tumour can occur simultaneously or the Castleman lesion can precede the former by several years [2] (Fig 30.2).

FDC proliferations resembling Hodgkin lymphoma Some FDC proliferations can mimic Hodgkin lymphoma. The tumour shows either a diffuse or a nodular growth pattern, the latter mimicking nodular lymphocyte predominant Hodgkin lymphoma. In these lesions the lymph node architecture is obliterated by a proliferation showing scattered large atypical cells in a background of small lymphocytes. The neoplastic cell component consists of large cells with characteristic morphological features. Some

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Fig 30.1 Follicular dendritic cell sarcomas have a range of morphological features from sarcomatous (top two rows) through to those with Hodgkin-like features (bottom row).

Fig 30.2 Histological appearances of follicular dendritic cell sarcoma associated with Castleman disease.

atypical cells show oval nuclei with slightly irregular outlines and a pepper-and-salt or powdery chromatin pattern. Some others showed bizarre morphological features with very irregular twisted nuclei associated with pseudointranuclear inclusions mimicking nucleoli. Some binucleated cells bear a distinct resemblance to follicular dendritic cells. Cells showing an lymphocyte predominant (LP) or Reed–Sternberg-like morphology are observed. The background lymphocytes are essentially normal and associated with scattered plasma cells, with occasional eosinophils in some areas (Fig 30.3). All atypical cells are strongly positive for FDC-associated antigens (CD21, CD23, CD35, CNA.42,

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clusterin, fascin). Immunostaining with the latter antibodies highlights atypical cells that display numerous cytoplasmic prolongations (Fig 30.4).

Castleman disease with atypical interfollicular spindle cells Occasionally, hyaline–vascular Castleman disease shows ‘dysplastic’ FDCs in the follicles and interfollicular atypical spindle cell proliferations of uncertain nature. Although the latter cells show morphological similarities to FDC, they are often negative for all FDC markers (CD21, CD23, CD35, CNA.42) and positive for only

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Follicular Dendritic Cell Proliferations and Related Entities

Fig 30.3 Morphology of follicular dendritic cell proliferations resembling Hodgkin lymphoma.

CD21

CD23

vimentin. Large numbers of T cells are present in these interfollicular areas.

FDC proliferations associated with EBV (so-called inflammatory pseudotumours) In the heterogeneous group of inflammatory pseudotumours a distinct category expressing FDC markers has been recognised in liver and spleen and more rarely in lymph nodes [4,5]. Patients present with fever, general malaise and weight loss. These tumours, particularly in the liver, are of large size (>10 cm in diameter), well circumscribed, tan, with hemorrhagic areas and yellow necrosis. They consist of a mixed population of inflammatory cells, rich in plasma cells, and a proliferation of spindle cells resembling fibroblasts. A significant number of fibroblast-like cells show two nuclei and some atypical cells with Reed–Sternberg-like features are commonly observed. The spindle cells exhibit FDC phenotypes. In a significant proportion of cases these fibroblastlike cells are weakly positive for LMP1, indicating latent infection with EBV. In addition, in situ hybridisation reveals a large number of EBER-positive spindle cells [4,5,8]. On the basis of the detection of clonal EBV these proliferations

Fascin

Fig 30.4 The immunophenotype of follicular dendritic cell proliferations associated resembling Hodgkin Lymphoma.

are likely to be low-grade FDC sarcomas [5]. Inflammatory pseudotumours of lymph nodes are usually negative for EBV and do not develop from FDCs [9] (Fig 30.5).

Unclassifiable lesions Occasional FDC proliferations are difficult to classify because of unusual morphological and phenotypic features. Thus, some tumours that are strongly positive for FDC markers (CD21, CD23, CD35) also may express CD68 (a macrophageassociated antigen) and even occasionally the CD45 antigen may be expressed (Table 30.1).

Immunophenotype FDC proliferations are positive for two or more FDC-associated antigens (CD21, CD23, CD35, CNA.42, clusterin and fascin) and negative for B- and T-cell and histiocytic antigens and CD45. Most cases are positive for vimentin and occasional cases are focally positive for epithelial membrane antigen (EMA). Non-neoplastic lymphocytes admixed with malignant cells are predominantly of T-cell phenotype (Fig 30.6).

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Liver

Low power H&E

High power H&E

Pleomorphic FDCs

RS-like FDCs

CD21

EBV LMP

EBER in situ

EBER plus CD21

Fig 30.5 A follicular dendritic cell proliferation associated with EBV. This patient presented with a massive liver tumour. A needle biopsy was diagnosed initially as Hodgkin Lymphoma because of the presence of Reed-Sternberg-like cells (top row middle and right). After liver resection (top left) this tumour proved to be a follicular dendritic cell tumour with a strong inflammatory component (so called ‘inflammatory pseudotumour’) positive for EBV (bottom row). Table 30.1 Different types of follicular dendritic cell (FDC) proliferations FDC sarcoma (EBV−): • FDC sarcoma plus Castleman tumour • FDC proliferation resembling Hodgkin lymphoma – nodular – diffuse • FDC proliferation associated with EBV (so-called inflammatory pseudotumours)a Unclassifiable lesions: • Castleman disease with atypical interfollicular spindle cells • FDC tumours with unusual morphological and phenotypic features a

In the heterogeneous group of inflammatory pseudotumours, only proliferations expressing FDC markers are taken into consideration. EBV, Epstein–Barr virus.

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CD21

Fascin

CNA 42 Fig 30.6 The immunophenotype of follicular dendritic cell sarcoma.

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References 1. Monda L, Warnke R, Rosai J. A primary lymph node malignancy with features suggestive of dendritic reticulum cell differentiation. A report of 4 cases. Am J Pathol 1986;122:562–72. 2. Chan J. Proliferative lesions of follicular dendritic cells: an overview, including a detailed account of follicular dendritic cell sarcoma, a neoplasm with many faces and uncommon etologic associations. Adv Anat Pathol 1997;6:387–411. 3. Chan J. Inflammatory pseudotumor: a family of lesions of diverse nature and etiologies. Adv Anat Pathol 1996;3:156–71. 4. Arber DA, Kamel OW, van de Rijn M, et al. Frequent presence of the Epstein-Barr virus in inflammatory pseudotumor. Hum Pathol 1995;26:1093–8. 5. Selves J, Meggetto F, Brousset P, et al. Inflammatory pseudotumor of the liver. Evidence for follicular dendritic reticulum cell proliferation associated with clonal Epstein-Barr virus. Am J Surg Pathol 1996;20:747–53.

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6. Chan JK, Fletcher CD, Nayler SJ, Cooper K. Follicular dendritic cell sarcoma. Clinicopathologic analysis of 17 cases suggesting a malignant potential higher than currently recognized. Cancer 1997;79:294–313. 7. Soriano AO, Thompson MA, Admirand JH, et al. Follicular dendritic cell sarcoma: a report of 14 cases and a review of the literature. Am J Hematol 2007;82:725–8. 8. Delsol G, Diebold J, Isaacson PG, et al. Pathology of the spleen: report on the workshop of the VIIIth meeting of the European Association for Haematopathology, Paris 1996. Histopathology 1998;32:172–9. 9. Facchetti F, De Wolf-Peeters C, De Wever I, Frizzera G. Inflammatory pseudotumor of lymph nodes. Immunohistochemical evidence for its fibrohistiocytic. Am J Pathol 1990; 137:281–9.

31

Langerhans Cell Histiocytosis

Langerhans cell histiocytosis is a relatively uncommon malignancy of Langerhans cells, with a range of clinical presentations and a considerable gradient of malignancy from a virtually benign disease to an aggressive sarcoma-like tumour. This malignancy has had numerous different names in the past including histiocytosis X, Langerhans cell granulomatosis, solitary eosinophilic granuloma, Hand–Schüller– Christian disease and Letterer–Siwe disease. Some authorities, including the 2008 World Health Organization (WHO) classification, recommend distinguishing Langerhans cell histiocytosis with typical morphological features from a pleomorphic variant known as Langerhans cell sarcoma [1,2].

Clinical presentation and follow-up Most cases occur in children and adolescents with adult cases being rare. In spite of the somewhat arcane eponyms referred to above, they do encapsulate rather economically the different clinical presentations of this disease that determine to a significant degree the prognosis. Solitary eosinophilic granuloma is a single focus of Langerhans cells usually in bone such as the skull, femur or ribs. This tends to occur in older children, and have the most mature cytology and the best prognosis. Hand–Schüller–Christian Disease is similar save that it requires several foci of tumour deposition in the same organ, usually bone. Letterer–Siwe disease is disseminated multisystem involvement by Langerhans cell histiocytosis. Typically this arises in young children who are systemically ill and have a poor prognosis. The prognosis of this condition is related predominantly to the degree of organ involvement more than any cytological or histological features [3]. The sarcomatous variant does worse of all but it is always disseminated at presentation.

Adult smokers do get small collections of Langerhans cell histiocytosis in their lungs which most authorities believe is more a reactive inflammatory phenomenon than a tumour [4].

Histology The histology can be quite variable but relies on the identification of the typically spindly Langerhans cells with their deeply grooved and elongated nuclei. These cells are often surrounded by a host of other reactive cell types such as eosinophils and macrophages which can obscure the diagnosis (Fig 31.1). In the more aggressive or sarcomatous forms of the disease, the typical morphology is lacking and the diagnosis may need to be made by immunocytochemistry (Fig 31.2). In general morphology is not a good indicator of clinical behaviour [5]. Langerhans cell histiocytosis may be seen as a separate focus in association with a number of lymphomas, both Hodgkin and non-Hodgkin types. It is unclear what relationship it has to the lymphoma. There are also scattered reports of isolated foci of Langerhans cell histiocytosis in a wide variety of different pathological specimens. Again the significance of this finding is unknown [6] (Fig 31.3). Recent studies have shown identical clonal rearrangements in T-cell lymphoblastic leukemias and subsequent Langerhans cell histiocytosis or in FLs lymphomas and associated histiocytic tumors, indicating a common clonal origin in tumors of different lineages [7, 8, 9].

Immunophenotype Immunostaining is generally the cornerstone of modern diagnosis. The tumour cells have the immunophenotype of

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Langerhans Cell Histiocytosis

CD1a

CD1a Fig 31.1 In a typical case of Langerhans cell histiocytosis in a lymph node, the paracortex is extensively replaced by neoplastic Langerhans cells. The pattern has similarities to dermatopathic lymphadenopathy but the infiltrate is too extensive and pleomorphic to be reactive. Neoplastic cells can frequently be detected in lymphatic sinuses (bottom right).

Langerhans cells, being S100+, langerin+ and CD1a+, and lacking virtually all other lymphoid markers (they may show weak positivity for CD4 and CD68) [1,10,11]. Surprisingly most cases are placental alkaline phosphatase positive which shows that they are not entirely identical to normal Langerhans cells. Langerhans cell histiocytosis is also defined ultrastructurally by the possession of Birbeck granules, a cytoplasmic structure seen only in Langerhans cells. However, for most

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diagnosticians electron microscopy rarely gets performed for a variety of reasons and the diagnosis rests largely on morphology and immunostaining.

Cytogenetics No consistent chromosomal abnormalities have been described.

CHAPTER 31

Langerhans Cell Histiocytosis

CD1a

CD1a

CD68

S100

Fig 31.2 This case was a terminal transformation into an aggressive sarcoma from an earlier typical case of Langerhans cell histiocytosis. The pleomorphic cytology and the extensive infiltration of adjacent tissues can be seen. Of interest in this case is the presence of numerous giant cells some of which are neoplastic Langerhans cells (CD1a), the remainder being histiocytic (CD68).

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Langerhans Cell Histiocytosis

CD1a

CD20

S100

CD3

Fig 31.3 Focal collection of Langerhans cells in an otherwise unremarkable reactive tonsil. It is unclear what relevance such a finding has for the clinical care of the patient.

References 1. Pileri S, Grogan T, Harris N, et al. Tumors of histiocytes and accessory dendritic cells. An immunohistochemical approach to classification from the International Lymphoma Study Group based on 61 cases. Histopathology 2002;41:1–29. 2. Swerdlow SH, Campo E, Harris NL, et al., eds. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 4th edn. Lyon: IARC Press, 2008. 3. Greenberger JS, Crocker AC, Vawter G, Jaffe N, Cassady JR. Results of treatment of 127 patients with systemic histiocytosis. Medicine (Baltimore) 1981;60:311–38. 4. Vassallo R, Ryu JH, Colby TV, Hartman T, Limper AH. Pulmonary Langerhans’-cell histiocytosis. N Engl J Med 2000;342:1969–78. 5. Risdall RJ, Dehner LP, Duray P, Kobrinsky N, Robison L, Nesbit ME Jr. Histiocytosis X (Langerhans’ cell histiocytosis). Prognostic role of histopathology. Arch Pathol Lab Med 1983;107: 59–63.

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6. Lam KY, Chan AC, Wat MS. Langerhans cell histiocytosis forming an asymptomatic solitary nodule in the spleen. J Clin Pathol 1996;49:262–4. 7. Chen W, Lau SK, Fong D, et al. High frequency ofclonal immunoglobulin receptor gene rearrangementsin sporadic histiocytic/ dendritic cell sarcomas.Am J Surg Pathol. 2009;33:863–73. 8. Feldman AL, Berthold F, Arceci RJ, et al. Clonalrelationship between precursor T-lymphoblasticleukaemia/lymphoma and Langerhans-cell histiocytosis.Lancet Oncol. 2005;6:435–7. 9. Feldman AL, Arber DA, Pittaluga S, et al. Clonallyrelated follicular lymphomas and histiocytic/dendritic cell sarcomas: evidence for transdifferentiationof the follicular lymphoma clone. Blood.2008;111:5433–9. 10. Chikwava K, Jaffe R. Langerin (CD207) staining in normal pediatric tissues, reactive lymph nodes, and childhood histiocytic disorders. Pediatr Dev Pathol 2004;7:607–14. 11. Lau SK, Chu PG, Weiss LM. Immunohistochemical expression of Langerin in Langerhans cell histiocytosis and non-Langerhans cell histiocytic disorders. Am J Surg Pathol 2008;32:615–9.

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Myeloid Leukaemias (Myeloid Sarcoma)

Tumorous deposits of acute (AML) or chronic myeloid leukaemias (CML) may occur at any site in the body, although leukaemias with monocytic differentiation tend to have a predilection for the oral cavity. Tumours with a high content of myeloperoxidase may have a slight greenish tinge, hence the old name for this tumour of ‘chloroma’.

Clinical presentation and follow-up Myeloid sarcomas may occur at any time in the course of a myeloid leukaemia and indeed may present as a solitary tumour months or even years before the onset of actual myeloid leukaemia. In this circumstance excision and local radiotherapy are believed to be all that are necessary in the way of treatment, although the rarity of this presentation means that there is little hard evidence to go on. Otherwise the prognosis is that of the underlying myeloid leukaemia. If the sarcoma is composed of blast cells and the marrow reveals myelodysplasia or myeloproliferation, the tumour is considered to be evidence of blast transformation and the patient is usually treated for AML.

Histology Usually these tumours are composed of pleomorphic medium- to large-sized blast cells. Unless the patient is known to have AML most pathologists initially think that they are dealing with an aggressive lymphoma and the true nature becomes apparent only on immunophenotyping (yet one more reason for immunophenotyping all ‘lymphoid lesions’!). Occasionally the infiltrate is composed of welldifferentiated haematopoietic cells usually with the appearance of CML rather than one of the other myeloproliferative conditions. Detailed accounts of the features of myeloid leu-

kaemias can be found in the excellent new 2008 WHO Atlas on Tumours of Haematopoietic and Lymphoid Tissues and in a number of bone marrow histology texts [1–3] (Fig 32.1).

Immunophenotype The immunophenotype is identical to that of myeloid leukaemia being negative for B- and T-cell markers but positive for myeloperoxidase and/or histiocytic markers such as lysozyme or CD68. Other markers that may be positive are CD31, CD34 and CD43, and these can be misleading because they are not lineage specific, e.g. CD43 positivity may suggest a T-cell lymphoma but the key is to be suspicious of a T-cell lymphoma lacking all other T-cell markers (Fig 32.2).

Cytogenetics The importance of cytogenetic abnormalities in myeloid leukaemia is now fully recognised in the new World Health Organization (WHO) classification of leukaemia [1]. Myeloid sarcomas are presumed to share the same profile as the underlying leukaemia, although the cytogenetic investigations are usually performed on the blood or marrow when that is available. In the case of solitary sarcomas the possibility of AML is not often considered so that appropriate material is not taken often for genetic analysis. A recent detailed study of 92 cases showed, by using both fluorescence in situ hybridisation and conventional karyotyping, chromosomal aberrations in just over half of the cases. The most common were monosomy 7 (10.8%), trisomy 8 (10.4%) and MLL rearrangements (8.5%) [4]. Nucleophosmin mutations have also been described in a small number of cases [5].

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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CHAPTER 32

Myeloid Leukaemias (Myeloid Sarcoma)

Cytokeratin

Myeloperoxidase

CD68

CD34

CD43

Fig 32.1 Acute myeloid leukaemia (AML) presenting as a tumour in the skin. The phenotype is that of an M1/M2 AML being strongly myeloperoxidase positive but weak to negative for CD68 (the larger positive cells are phagocytic macrophages). Blastic markers such as CD34 and CD43 are commonly positive in these tumours and should not interpreted as signs of a tumour of other lineages.

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CHAPTER 32

Myeloid Leukaemias (Myeloid Sarcoma)

Cytokeratin

CD3

Myeloperoxidase

CD31

CD68

Fig 32.2 An example of a predominantly monocytic myeloid leukaemia presenting in the parotid gland. In contrast to the myeloid sarcoma this tumour is largely negative for myeloperoxidase but strongly positive for CD68. CD31 is another blastic marker similar to CD34 or CD43 that is commonly positive on these tumours. Note the lack of T-cell staining (CD3) which along with other lymphoid markers distinguishes these tumours from lymphomas, with which they may be confused morphologically.

References 1. Swerdlow SH, Campo E, Harris NL, et al., eds. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 4th edn. Lyon: IARC Press, 2008. 2. Brown D, Gatter K, Natkunam Y, Warnke R. Bone Marrow Diagnosis: An illustrated guide. Oxford: Blackwell Scientific, 2006.

3. Bain B, Clark D, Wilkins B. Bone Marrow Pathology. Oxford: Wiley-Blackwell, 2009. 4. Pileri SA, Ascani S, Cox MC, Campidelli C, Bacci F, Piccioli M, et al. Myeloid sarcoma: clinico-pathologic, phenotypic and cytogenetic analysis of 92 adult patients. Leukemia 2007;21:340–50. 5. Falini B, Lenze D, Hasserjian R, et al. Cytoplasmic mutated nucleophosmin (NPM) defines the molecular status of a significant fraction of myeloid sarcomas. Leukemia 2007;21:1566–70.

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Index

acquired immunodeficiency syndromes 247–8 acute lymphoblastic leukaemia 63 acute myeloid leukaemia 252 acute necrotising tonsillitis 35 adult T-cell lymphoma/leukaemia 61, 169 clinical features 169 differential diagnosis 171 haematological features 169 histology 169 HTLV-1 169–71 immunohistology 169, 170 prognosis and treatment 171 aggressive B-cell lymphoma 138 aggressive NK-cell leukaemia 61, 164 clinical features 164–6 cytogenetics 167 histology 166, 167, 168 immunophenotype 166–7 prognosis and treatment 167 AILD 202 amyloid in the small intestine 98 in the spleen 98 anaplastic large B-cell lymphoma 134, 135, 137 anaplastic large cell lymphoma (ALCL) 200, 208, 240 ALK− 208, 214–19 ALK+ 208–14 clinical features 208, 214 common type 209, 210 cytogenetics 214 differential diagnosis 215–18 fiction ALK-1 214 giant cell rich 209, 211 histology 208–13, 214–15 Hodgkin-like 212, 213 immunophenotype 214, 215 lymphohistiocytic type 209, 210 prognosis and treatment 218, 219 sarcomatoid and other morphologic variants 212 small cell subtype 209–12 anaplastic tumours of non-lymphoid origin 136–7

angioendotheliomatosisproliferanssystemisata 145 angioimmunoblastic lymphadenopathy with dysproteinaemia 202 angioimmunoblastic T-cell lymphoma (T-AIL) 61, 202 clinical features 202 cytogenetics 205 differential diagnosis 205, 206 histology 202, 203–4 immunophenotype 202–5 prognosis and treatment 205–7 angiolymphoid hyperplasia 28, 30 angiotropic lymphoma 145 antibodies 2 important additional markers for haematopathology 2 monoclonal antibodies of diagnostic value 2, 4–11 pitfalls in immunohistochemistry 3–12 anti-CD30/Ber-H2 antibody 13 anti-EMA antibodies 12–13 antigen acquisition 15 asteroid bodies 51 ataxia telangiectasia 247 ATLL see adult T-cell lymphoma/leukaemia atypical hyperplasia 205 Bartonella henselae 51, 55 B-cell lymphoblastic lymphoma/leukaemia 60, 63, 72 blood involvement 63 clinical features 63 cytogenetics 63–4 differential diagnosis 64–7 histology 63, 64 immunophenotype 63, 64, 65 prognosis and treatment 67 B-cell lymphoma 251 unclassifiable 148–52 B-cell prolymphocytic lymphoma 77, 78 prognosis and treatment 77 benign accumulations of histiocytes 254 benign glandular inclusions 56 biopsy 1–2

Birbeck granules 251, 262 blasticplasmacytoid dendritic cell neoplasm 66, 252–3 blastic transformation 121, 124 blastic variant 129 body cavity lymphomas 147 Borrelia burgdorferi 100, 104 Brutonagammaglobulinaemia 247 Burkitt lymphoma 66, 155 clinical features 155 cytogenetics 156–9 differential diagnosis 159 Epstein–Barr virus 157 histology 155–6 immunohistology 156, 157, 158–9 prognosis and treatment 159 subtypes 157–9 Castleman disease 21, 34, 38 with atypical interfollicular spindle cells 256 follicular dendritic cell sarcoma associated 255, 258 hyaline–vascular type 21, 24, 25–6 large B-cell lymphoma arising in HHV8associated multicentricCastleman disease 147, 150 multicentric or systemic 21–5, 28, 147, 150 plasma cell variant 21, 27 Castlemantumour 112–15 cat-scratch disease 21, 37, 51, 55–6 CD30 molecule 208, 214, 215 centroblasticlymphoma 134, 136 centrocytic lymphoma 121 Chlamydia trachomatis 51 chloroma 265 chronic lymphocytic leukaemia(CLL) 60, 66, 75 blood involvement 75 clinical features 75 cytogenetics 76 differential diagnosis 78–80 histology 75, 76, 77 immunophenotype 75–6, 77, 78 lymphoplasmacytoid variant 75 prognosis and treatment 80

The Diagnosis of Lymphoproliferative Diseases, Second Edition. Kevin C. Gatter, Georges Delsol, Roger A. Warnke, Francesco Pezzella. © 2012 Kevin C. Gatter, Georges Delsol, Roger A. Warnke and Francesco Pezzella. Published 2012 by Blackwell Publishing Ltd.

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Index classic intestinal T-cell lymphoma – type I – EATL 178 clinical features 178 cytogenetics 178 histology 178 immunophenotype 178, 179, 180 prognosis and treatment 178 CMV-associated lymphadenopathy 35, 39 coeliac disease 178, 179 common variable immune deficiency 246, 247 congenital immune deficiency syndromes 244–7 Crohn disease 182 cutaneous involvement by monoblasticleukaemia 252 cyclin D1 expression 90, 91 dermatopathic lymphadenopathy 21, 41–3, 45 diffuse large B-cell lymphoma 12, 60, 66, 91, 110, 134, 135, 152, 208, 238 with anaplastic morphology 217 borderline cases 148–52 with chronic inflammation 141 clinical features 134 cytogenetics 136 differential diagnosis 136–8, 140 histology 134–5, 136, 137 immunophenotype 135, 137, 138, 139 morphologic variants 134–5 prognosis and treatment 138–9, 141 with a sinusoidal growth pattern 146, 149 subtypes 139–48, 149–50 diffuse large cell (cleaved or non-cleaved) 134 diffuse lymphocyte predominance Hodgkin lymphoma 221 drug-induced lymphadenopathy 21, 43, 46 Dutcher bodies 92, 93 enteropathy-associated T-cell lymphoma 178 classic (type I) 178–9, 180 clinical features 178, 179 cytogenetics 178, 179 histology 178, 179 immunophenotype 178, 179, 180, 181 monomorphic (type II) 179, 181 prognosis and treatment 178, 179 Epstein–Barr virus infection 21, 35, 38–9, 157, 16–17, 172, 255 Epstein–Barr virus-positive diffuse large B-cell lymphoma of elderly people 141, 145 extranodal marginal zone B-cell lymphoma 100 extranodal NK/T-cell lymphomas: nasal type 172, 173 clinical features 172, 174 cytogenetics 172 histology 172, 175 immunophenotype 172, 176 prognosis and treatment 172 false-negative staining 3–12 false-positive staining 12 fixatives 1–2 follicle centre cell lymphoma 108 follicle lysis 32–4

follicular dendritic cell proliferations 255 clinical presentation and follow-up 255 EBV-associated (‘inflammatory pseudotumours’) 256–8 histology 255–8 immunophenotype 257, 258 resembling Hodgkin lymphoma 255–6, 257 follicular dendritic cells – abnormal 21 follicular dendritic cell sarcoma 251, 255, 256, 258 associated with Castleman disease 255, 256 follicular hyperplasia 20–35 follicular lymphoma 80, 108, 224 bone marrow involvement 108 clinical features 108 cytogenetics 111–13, 114 differential diagnosis 112–16, 117, 118–19 extranodal 112 grading 108, 110, 111, 118 histology 108–11, 112, 113 immunophenotype 111, 113, 114 ‘in situ’ 112, 116–17 low-power histology 112 Mann and Berard counting method 108, 110, 118 morphology 109 paediatric 112–13, 115 primary intestinal 112, 115 prognosis and treatment 118 T-cell 194 formalin 1–2 fungal lymphadenitis 21, 53

histiocytic lymphoma 249 histiocytic medullary reticulosis 249 histiocytic reticulum cell sarcoma 249 histiocytic sarcoma 137, 217, 249 blood involvement 249 clinical features 249 cytogenetics 251 differential diagnosis 251–4 histology 249, 250 immunophenotype 249–51 prognosis and treatment 251 histiocytosis X 261 HIV-associated lymphomas 247–8 HIV-related lymphadenopathy 21, 32–5, 36–7 and Castleman disease 25, 34, 38 cerebral lymphomas 141 primary effusion lymphomas 147 Hodgkin lymphoma 200, 205, 217, 218, 220 granulomatous variant 229, 234 lymphocyte-depletion 237–40 lymphocyte-rich 233–7, 238 mixed cellularity 230–3, 235–7 monoclonal antibodies 2 nodular lymphocyte-predominant 220–4, 225–6 nodular sclerosis 225–30, 231–2, 233–4 HTLV-1 retrovirus 169–71, 193 human herpes virus 8 (HHV-8) in multicentricCastleman disease 25, 28 large B-cell lymphoma arising in 147, 150 hypergammaglobulinaemia 164 hyperplasia, atypical 205

Gaucher disease 53, 254 germinal centres– progressive transformation 21, 29–32 granulocytic sarcoma 252 granulomatous conditions 21, 47–56, 92, 229, 234

immunoblasticlymphoma 134, 136 immunocytochemistry 2 immunocytoma 92 blood involvement 92 clinical features 92 cytogenetics 93 differential diagnosis 93, 94 heavy chain diseases 93–5 histology 92, 93 immunophenotype 92, 93–4 prognosis and treatment 95 immunodeficiency-associated lymphoproliferative disorders 242 congenital 244–7 HIV-associated lymphomas 247–8 post-transplantation 242–4, 245, 246 immunohistochemistry, pitfalls in 3–12, 14, 17 immunoperoxidase staining 2 immunoproliferative small intestinal disease 95 immunostaining 2 inflammatory pseudotumours 255, 257–9 interdigitating dendritic cell sarcoma 249, 251–2 intermediate lymphocytic lymphoma 121 intestinal lipodystrophy 51 intestinal T-cell lymphoma classic (type I – EATL) 178–9, 180 clinical features 178, 179 cytogenetics 178, 179 histology 178, 179 immunophenotype 178, 179, 180, 181 monomorphic (type II – EATL) 179, 181 prognosis and treatment 178, 179

haematopoietic neoplasms 251 haematoxylin bodies 41 haemophagocytic syndrome 43, 47 hairy cell leukaemia 60, 86 blood involvement 86 in the bone marrow 86, 88 clinical features 86 cyclin D1 expression 90, 91 cytogenetics 86 differential diagnosis 86–91 histology 86, 87–9 immunophenotype 86, 90–1 in the liver 86 in lymph node 86, 89 prognosis and treatment 91 in the spleen 86, 87 variant 91 Hand–Schüller–Christian disease 261 Hans classifier 139, 141 heavy chain diseases 93–5 Helicobacter pylori 100, 102, 104 hepatosplenicT-cell lymphoma 182–3 herpes lymphadenitis 35–7, 40 high-grade B-cell lymphoma 2 histiocytes, benign accumulations of 254

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Index intrafollicularneoplasia 112, 116–19 intravascular large B-cell lymphoma 145–6, 148 intravascular lymphomatosis 145 kala-azar (leishmaniasis) 20, 24 Kaposi sarcoma 35, 36 primary effusion lymphomas 147, 148 keratin positivity in lymphomas 15 Ki-1 antibody 208, 218, 251 Kikuchi disease 21, 37–41, 42, 138 Kimura disease 21, 28–9 Langerhans cell granulomatosis 261 Langerhans cell histiocytosis 4, 7, 10, 11, 61, 249, 251, 261 clinical presentation and follow-up 261 cytogenetics 262 histology 261, 262–4 immunophenotype 261 Langerhans cell sarcoma 261 large B-cell lymphoma 224–5 arising in HHV8-associated multicentricCastleman disease 147, 150 expressing the ALK kinase 146, 149 large granular lymphocytic leukaemia 164 clinical features 164 cytogenetics 164 histology 164, 165–6 immunophenotype 164 prognosis and treatment 164 leishmaniasis (kala-azar) 20, 24 Lennert lymphoma 194, 196, 240 lepromatous leprosy 50, 53 leprosy 21, 50, 53 lethal midline granuloma 172 Letterer–Siwe disease 261 leukocyte common antigen in non-lymphoid tumours 16 lipidoses 21, 53 loss of B- or T-cell associated antigens 14–15 loss of leukocyte common antigen 14 low-grade B-cell lymphoma MALT type 2, 100 monoclonal antibodies 2 luetic lymphadenitis 25 lupus lymphadenitis 21, 37–41, 43 lymphangiography effect 21, 47, 49–50 lymph node biopsy 1 lymph node inclusions 53, 56 lymph node involvement by monoblasticleukaemia 252 lymphocyte-depletion Hodgkin lymphoma 61, 220, 237 clinical features 237 differential diagnosis 237–40 extranodal involvement 237 morphological features 237, 238 lymphocyte-predominant Hodgkin lymphoma see nodular lymphocyte-predominant Hodgkin lymphoma lymphocyte-rich Hodgkin lymphoma 220, 233–7, 238 lymphoepithelial lesions 100, 101–2 lymphoepithelioid cell lymphoma 194, 196, 240 lymphogranulomavenereum 21, 51

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lymphoma classification 60 lymphomatoidgranulomatosis 144, 146 lymphomatoidpapulosis and regressing atypical histiocytosis 216 lymphomatous polyposis 121, 125 lymphoplasmacytic lymphoma 92 blood involvement 92 clinical features 92 cytogenetics 93 differential diagnosis 93, 94 heavy chain disease 93–5 histology 92, 93 immunophenotype 92, 93–4 prognosis and treatment 95 lymphoproliferations in immune deficiency statessee immunodeficiency-associated lymphoproliferative disorders malignant angioendotheliomatosis 145 malignant histiocytosis/true histiocytic lymphoma 217, 249 malignant lymphoma of plasmacytoid T-cells 252 MALT lymphomas 100, 102, 104 Mann and Berard counting method 108, 110, 118 mantle cell lymphoma 2, 4, 5, 9, 13, 60, 62, 65, 72, 78–80, 91, 104, 118, 121 blastic transformation 121, 124 blastoid/pleomorphic 129, 130, 131, 132 blood involvement 122 clinical features 121, 122 cytogenetics 128, 129 differential diagnosis 128–31 histology 121–6 immunophenotype 122–8 in situ 122, 126 mantle zone pattern 121, 122, 127 morphology 122 prognosis and treatment 132 marginal zone B-cell lymphoma 60, 100 blood involvement 100 clinical features 100 cytogenetics 102 differential diagnosis 102–4 extranodal 100 follicular colonization 103 histology 100, 101–2, 103 immunophenotype 102, 103 lymphoepithelial lesions 100, 101–2 nodal 104–6 prognosis and treatment 104–6 measles 21, 29, 30 metastatic carcinoma 217 methotrexate 43, 46 miscellaneous unexpected reactivities 13–4 mixed cellularity Hodgkin lymphoma 220, 230 clinical features 230 immunophenotype 233, 236–7 morphological features 230–3, 235 molecular techniques 17–8 monoblasticleukaemia, cutaneous and/or lymph node involvement by 252 monocytoid B-cell lymphoma 104 monocytoid B lymphocytes 20

monomorphic intestinal T-cell lymphoma type II – EATL 178, 179 clinical features 179 cytogenetics 179 histology 179 immunophenotype 179, 181 prognosis and treatment 179 mucosa associated lymphoid tissue (MALT) 100 mycosis fungoides/Sézary syndrome 61, 189 clinical features 189, 190 cytogenetics 193 histology 189 immunophenotype 189, 191–2 prognosis and treatment 193 myeloid leukaemia 66–7, 252, 265 clinical presentation and follow-up 265 cytogenetics 265 histology 265, 266 immunophenotype 265, 267 myeloid sarcoma 265 necrotising lymphadenitis without neutrophil polymorphs 37 needle biopsy 1 nevus cell inclusion 53 Niemann–Pick disease 53, 254 NK-cell leukaemiasee aggressive NK-cell leukaemia NK-cell type 61 nodal marginal zone B-cell lymphoma 104–6 nodular lymphocyte-predominant Hodgkin lymphoma 3, 5, 6, 10, 12, 29, 32, 115, 220 clinical features 220 cytogenetics 222 differential diagnosis 223–5 histology 220–1 immunohistology 221–3, 224, 225 prognosis and treatment 224, 225–6 nodular paragranuloma 220 nodular sclerosis Hodgkin lymphoma 220, 225 clinical features 225 cytogenetics 227–9 differential diagnosis 229, 233–4 granulomatous variant 229, 234 histology 225–6, 227, 228 immunophenotype 226–7, 228–9, 230, 231–2, 233 prognosis and treatment 229–30 non-lymphoid tumours 251 non-specific follicular hyperplasia 20, 21 normal lymphoid structures 18 paracortical expansion 21, 35–43 peripheral T-cell lymphoma 194, 240 clinical features 194 cytogenetics 199 differential diagnosis 199–200 histology 194, 195–6, 197 immunophenotype 194–9, 200 prognosis and treatment 200 unspecified 194, 205 persistent generalised lymphadenopathy 32 phenytoin 43 pitfalls in immunohistochemistry 3–12, 14, 17 plasmablasticlymphoma 97, 147

Index plasmacytoid monocytes 21, 25–6, 252 plasmacytoma/myeloma 96, 97, 98, 99 blood involvement 96 in the bone marrow 96, 97 clinical features 96 cytogenetics 96–7 differential diagnosis 97–8, 99 histology 96, 97, 98 immunophenotype 96 multiple myeloma 98 nuclear cyclin D1 96–7 prognosis and treatment 98 smouldering myeloma 98 POEMS syndrome 21–5, 97 post-transplantation lymphoproliferative disorders (PTLDs) 242 classic Hodgkin lymphoma-type 244, 246 early lesions 243 monomorphic 244, 245–6 pathology 242–4, 245, 246 polymorphic 243–4 prognosis and treatment 244 primary cutaneous anaplastic large cell lymphoma 215–6 primary cutaneous diffuse large B-cell lymphoma, leg type 141, 144 primary cutaneous follicular lymphoma 110–11 primary cutaneous γ/δ T-cell lymphoma 185, 187 primary diffuse large B-cell lymphoma of the central nervous system 141, 143 primary effusion lymphomas 147–8 primary mediastinal large B-cell lymphoma 144–5 clinical features 144 cytogenetics 145 differential diagnosis 145 histology 144–5 immunophenotype 145, 147 prognosis and treatment 145 pseudolymphoma 43 PTLDs see post-transplantation lymphoproliferative disorders reactive and infective conditions 20 reactive follicular hyperplasia 20, 22, 112, 115–16, 223–4 reactive lesions 199–200

reactive lymphoproliferation 137–8 REAL classification 59, 60–1, 77, 104, 108, 134, 157, 172, 185, 189, 194, 208, 220 Reed–Sternberg (like) cells in reactive lesions 238, 239 regressing atypical histiocytosis 216, 249 rheumatoid arthritis 21, 25, 28, 164 Richter transformation 75, 76 rituximab 14, 118, 132 Rosai–Dorfman disease 21, 43–7, 48 round cell tumours 67 sarcoidosis 21, 50–1, 54 Schaumann bodies 51 severe combined immune deficiency 247 Sézary syndrome 61, 189 silicon deposition 21, 47, 50 sinus histiocytes– immature 20 sinus histiocytosis 21, 43, 46–7 sinus histiocytosis with massive lymphadenopathy (SHML) 43 sinus hyperplasia 21, 43–7 small lymphocytic lymphoma 60, 75, 164 blood involvement 75 clinical features 75 cytogenetics 76 differential diagnosis 78–80 histology 75, 76, 77 immunophenotype 75–6, 77, 78 lymphoplasmacytoid variant 75 prognosis and treatment 80 smouldering myeloma 98 splenic diffuse red pulp small B-cell lymphoma 85 splenic lymphoma 81, 91 blood involvement 81 with circulating villous lymphocytes 81 clinical features 81 cytogenetics 81 differential diagnosis 84, 85 histology 81, 82 immunophenotype 81, 83 prognosis and treatment 85 splenic marginal zone lymphoma 60, 81 diffuse variant 85 subcutaneous panniculitis-like T-cell lymphoma 185, 186–7 Sutton’s law 1

syphilis 21, 25–8 systemic lupus erythematosus (SLE) 37–41, 43 tattoos 47, 51 T-cell antigen heterogeneity 198 T-cell/histiocyte-rich B-cell lymphoma 139–41 T-cell lymphoblastic lymphoma/leukaemia 61, 65, 69 clinical features 69 cytogenetics 69–72 differential diagnosis 72–3, 74 histology 69, 70 immunophenotype 69, 71–3 prognosis and treatment 73 T-cell lymphomas 251 monoclonal antibodies 2 T-cell prolymphocyticleukaemia (PLL) 161 clinical features 161 cytogenetics 161 histology 161, 162 immunophenotype 161, 162 prognosis and treatment 161 toxoplasmosis 20, 21, 23 Tropheryma whippleii 51 true histiocytic lymphoma see histiocytic sarcoma tuberculoid leprosy 50 tuberculosis 21, 36, 47–50, 52, 229, 234 atypical 47, 50 tumours other than ALCL expressing ALK protein 218 typhoid 21 typhoid lymphadenitis 41, 44 T-zone lymphoma 194, 197 unexpected reactivity of monoclonal antibodies 12 viral lymphadenopathy 35, 38–9 Warthin–Finkeldey cells 29, 30, 221 Whipple disease 51, 56 WHO classification of lymphoid neoplasms 59, 60–1, 108, 110, 118, 134, 135, 141, 148, 152, 157, 185, 189, 194, 208, 215, 220, 242, 261, 265 Wiskott–Aldrich syndrome 247 X-linked lymphoproliferative disorder 247

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