Stephen Larsen

24th February, 2010

Lymphomas - classification and diagnosis

Two important references

http://apps.who.int/bookorders/anglais/detart1.jsp?sesslan=1&codlan=1&codcol=70&codcch=4002#$US122

http://www.amazon.com/Classification-Tumours-Haematopoietic-Lymphoid-Tissue/dp/9283224310$US104

Background

Thomas Hodgkin(1798-1866)

Thomas Hodgkin published in 1832 the first description of lymphoma, specifically of the form named after him, Hodgkin's lymphoma.

Name Hodgkin's Disease proposed in 1865 by Wiks.

History of Lymphoma Classification

Since Thomas Hodgkin’s first description of lymphoma in 1832, many other forms of lymphoma have been described, grouped under several proposed classifications.

1956, 1966 Rappaport’s Classification of NHL1966 Lukes-Butler (American) modern

classification of HL Kiel classification: in 1974, Karl Lennert

proposed a new system of classifying lymphomas based on cellular morphology and their relationship to cells of the normal peripheral lymphoid system.

The very popular 1982 Working formulation classification introduced the category Non-Hodgkin Lymphoma (NHL), itself divided into 16 different diseases.

REAL classification: In 1994 the Revised European-American Lymphoma (REAL) Classification attempted to apply immunophenotypic and genetic features in identifying distinct clinico-pathologic NHL entities.

The latest classification by the WHO (2001 updated in 2008) lists 43 different forms of lymphoma divided in four broad groups.

BLOOD, 1 DECEMBER 2008 VOLUME 112, NUMBER 12 p4384Classification of lymphoid neoplasms: the microscope as a tool for disease discovery

A practical way to think of lymphomaCategory Survival

of untreate

d patients

Curability

To treat or not to

treat

Non-Hodgkin lymphoma

Indolent Years Generally not curable

Generally defer Rx if asymptomatic

Aggressive

Months Curable in some

Treat

Very aggressive

Weeks Curable in some

Treat

Hodgkin lymphoma

All types Variable – months to years

Curable in most

Treat

Need for classification of Lymphomas

Classification is a language of medicine: diseases must be described, defined and named before they can be diagnosed, treated and studied.

A consensus on definitions and terminology is essential for both clinical practice and investigation.

A classification should contain diseases that are clearly defined, clinically distinctive, non-overlapping and that together comprise all known entities.

WHO classification of tumours of the haematopoietic and lymphoid tissues 4th edition, 2008 – true worldwide consensus classification of haematological malignancies:

WHO classification is based on the principles initially defined in REAL classification by the ILSG.

Guiding principle of the REAL and WHO classification is the attempt to define “real diseases” that can be recognised by available techniques and that appear to be distinct clinical entities.

Three important components to the process of developing classification of Hematological Malignancies:

First, recognising that the underlying causes of the neoplasm are often unknown and may vary. So, we use morphology, immunophenotype, genetic features, and clinical features to define diseases.

Second principle is that classification relies on building a consensus among as many experts as possible on the definition and nomenclature of the disease.

Third, while pathologists must take primary responsibility for developing a primary classification, involvement of clinicians is essential to ensure its usefulness and acceptance in daily practice.

There is no one “gold standard” by which all diseases are defined in the WHO classification.

So: 1. Morphology is always important. 2. Immuno-phenotype and 3. Genetic features are an important part of the definition of

haematologic tumors. Some diseases have a characteristic immunophenotype. Similarly in some lymphoid a specific genetic abnormality is the

key defining criteria, while others lack specific known genetic abnormality.

Some genetic abnormalities serve as prognostic factors.Most of the diseases in WHO classification are considered to be

distinct entities. However, some are not clearly defined and these are listed as provisional entities.

Conceptualizing lymphoma and its Classification

neoplasms of lymphoid origin, typically causing lymphadenopathy

leukemia vs lymphoma (extent of BM involvement)lymphomas as clonal expansions of cells at certain

developmental stages

Clinically useful classification

Diseases that have distinct• clinical features• natural history• prognosis• treatment

Biologically rational

classificationDiseases that have distinct• morphology• immunophenotype• genetic features• clinical features

stemcell

lymphoidprogenitor

progenitor-B

pre-B

immatureB-cell

memoryB-cell

plasma cellplasma cell

DLBCL,FL, HL

ALL

CLL

MM

germinalgerminalcentercenterB-cellB-cell

maturenaiveB-cell

Diagrammatic representation of B-cell differentiation and relationship to major B-cell neoplasms.

Diagrammatic representation of T-cell differentiation and function.

Main Groups in WHO Classification of Lymphoid Malignancies

B Cell NeoplasmsPrecursor B Neoplasms Mature B Cell Neoplasms

T Cell and NK Cell NeoplasmsPrecursor T Cell NeoplasmsMature T Cell and NK Neoplasms

Hodgkins Lymphoma

DiagnosisRadiographic features

• Ultrasound• Chest-x-ray film: the mediastinal

lymphonodes• Computerized tomography(CT)

• Chest• Abdomen, • Pelvis

• Gallium-67 scintigraphy• Whole-body positron emission

tomography(PET)

DiagnosisBiopsy----Pathological DiagnosisHistopathological classificationImmunomarkers

eg: NHL, diffused large cell, B cellCytogenetic studies

E.g; Mantle Cell LymphomaMolecular Studies

Diagnosis depends on biopsy of lymph nodes or other involved organs

Need enough tissue to assess cells and architectureopen bx vs core needle bx vs FNA A fine needle biopsy is rarely sufficient!

Peripheral blood: Blood involvement. Usually no changes in WBC and Platelet count

BM: non-specific changesHD: R-S cell in smear and biopsyNHL: increased lymphocyte

Laboratory FindingsFlow cytometry. Immunophenotyping of

biopsy material is important in NHL.Establish clonalityPattern of surface protein expression can be

diagnosticImmunological tests:

NHL: M-protein(+) Coombs’ test(+) hypoglobulinemiaOther findings:

ESR ↑LDH ↑

Disorder Common Phenotype Comments/Variations Potentially Associated Genetic Abnormalities

Chronic lymphocytic leukemia/small cell lymphocytic lymphoma

DR, CD19, CD20, CD5, CD22(-), CD23, CD10(-), CD11c+/-, CD25+/-, CD43, clonal SIgM and SIgD weak CD20 dim

Abnormalities of 13q, 14q, 11q

BCL-2 overexpressed Bright SIg, CD20, FMC7

Mantle cell lymphoma

DR, CD19, CD20, CD5, CD22, CD23(-), CD10(-), CD43, moderate clonal SIg (IgM > IgD) Cyclin D1 overexpressed t(11; 14)

Follicular lymphoma

DR, CD19, CD20, CD5(-), CD22, CD23+/-, CD10, CD11c(-), CD43(-), very bright clonal SIg CD10 negative <20% t(14; 18)

Overexpression of BCL-2

Marginal zone and associated lymphomas

DR, CD19, CD20, CD5(-), CD22, CD23(-), CD10(-), CD11c, CD25(-), CD103(-), moderate clonal SIg SIgD rare Trisomy 3

Hairy cell leukemia

DR, CD19, CD20, CD5(-), CD22, CD23(-), CD10(-), CD11c, CD25, CD103, moderate clonal SIg

SIgD common, very bright CD22 and CD11c No consistent alteration

Plasma cell dyscrasias

DR(-), CD19(-), CD20(-), CD22(-), CD38, CD45, clonal cIg, clonal SIg-/+

Two color bright CD38 and dim CD45 sensitive marker No consistent alteration

Laboratory FindingsChromosome changes in NHL:

t(14;18): Follicular lymphoma t(8;14): Burkitt’s lymphoma t(11;14): Mantle-cell lymphoma t(2;5): Ki-1+(CD30 +) Anaplastic

large-cell lymphoma 3q27: Diffuse large B-cell

lymphoma

Laboratory Findings

Molecular Biology changes in NHL• bcl-2• TCR• IgH

Differential Diagnosis Lymph nodes enlargement Specific: TB Infection

Non-specific: bacteria, virus,

Maligancies: haematological (leukaemia,etc); solid tumor metastasis

Connective tissue diseases Kikuchi’s lymphadenitis in women with SLE

Sarcoidosis

Reactive!

Differential DiagnosisFever

Infection ( bacteria , virus, TB, etc )

Connective tissue disease

Malignant tumors

Malignancies in related organs

Gastrointestinal tumors, liver cancer, etc

30%

22%8%7%

6%

6%

6%2%

14% Large B-cell

Follicular

Marginal zone

PTCL

Mantle cell

SLL/CLL

Mediastinal

Anaplastic L cell

Hodgkin’s

2002 SEER database. O’Connor

Three most common lymphomas

Follicular lymphomaDiffuse large B-cell lymphoma

Hodgkin lymphoma

Follicular lymphomamost common type of “indolent”

lymphomausually widespread at presentationoften asymptomaticnot curable (some exceptions)associated with BCL-2 gene

rearrangement [t(14;18)]cell of origin: germinal center B-cell

Follicular Lymphoma

defer treatment if asymptomatic (“watch-and-wait”)

several chemotherapy options if symptomatic

median survival: yearsdespite “indolent” label, morbidity and

mortality can be considerabletransformation to aggressive lymphoma can

occur

Diffuse large B-cell lymphoma

most common type of “aggressive” lymphoma

usually symptomaticextranodal involvement is commoncell of origin: germinal center B-cell or

activated B-like lymphomatreatment should be offeredcurable in ~ 40%

Diffuse Large B Cell Lymphoma

Hodgkin lymphoma

Classical Hodgkin lymphomas: Nodular sclerosisMixed cellularityLymphocyte-richLymphocyte depleted or not depleted

Nodular lymphocyte-predominant Hodgkin lymphoma

Hodgkin lymphomacell of origin: germinal centre B-cell Reed-Sternberg cells (or RS variants) in

the affected tissuesmost cells in affected lymph node are

polyclonal reactive lymphoid cells, not neoplastic cells

Reed-Sternberg cell

popcorn celllacunar cellclassic RS cell

(mixed cellularity) (nodular sclerosis) (lymphocytepredominance)

germinalcentreB cell

transformingevent(s)

loss of apoptosis

RS cellinflammatory

response

EBV?

cytokines

ConclusionThere are a large number of types of lymphoma.Therefore classification is important: a consensus on

definitions and terminology is essential for both clinical practice and clinical studies.

Classification has evolved as well learn more about the biology of distinct disorders.

Diagnosis requires an adequate biopsy. There are differing roles of flow cytometry, cytogenetics and moelcular studies for different disorders.