Lymphomas-B cell and Plasma Cell Neoplasms

Normal lymphoid cells undergo rearrangements within their antigen receptor genes, causing specificity for the immunoglobulin or T cell receptor that they produce

Monoclonal proliferations are presumed to be neoplastic; polyclonal populations are not

Lymphoid stem cell: TdT+, CD34+, HLA-DR+, then develops along B or T cell pathway

B cells

Develop from stem cells of yolk sac, fetal liver, spleen and bone marrow

B cells express surface immunoglobulin (Ig), composed of 2 heavy (H) and 2 light (L) chains (either kappa or gamma)

B cell antigen receptor loci may have 4 types of modification - recombination of variable, diversity and joining regions (VDJ); somatic hypermutation of V segments; immunoglobulin heavy chain gene class switching; and receptor editing

Defects may cause chromosomal translocations

1-diagram of IgH gene rearrangement

References: Archives 2003;127:1148

Early B cell precursor is TdT+, CD34+, HLA-DR+, then undergoes heavy (H) chain rearrangement and adds CD19, then adds CD10, then adds IgM heavy chain; then adds light (L) chain rearrangement and adds cytoplasmic IgM with heavy and light chains, then B cells express IgM and IgD with the same binding site, then adds CD20 (now called preB cell); then adds surface Ig, then adds CD21 and CD22 and drops TdT (now called B cell)

If B cell encounters an antigen that interacts with its variable region, it becomes a plasma cell

Precursor B cells contain immunoglobulin related components but not immunoglobulin; express CD179a and CD179b (precursor to light chains) as part of their pre-B cell receptor, which disappears when replaced with conventional light chains

B cells express surface immunoglobulin, consisting of heavy chain and kappa or gamma light chains; immunoglobulin is associated with CD79a/CD79b complex to form a B cell antigen receptor complex

IgH (heavy chain of immunoglobulin): 14q32; variable portion coded by VDJ regions

IgL (light chain of immunoglobulin): kappa on 2p11, lambda on 22q11; no diversity region is present

Heavy chain isotype switch: determines if immunoglobulin is IgM, IgD, IgG1-4, IgA1-2 or IgE (9 constant regions); mediated by switch genes

B cell lymphomas: clonal light chain rearrangement is usually specific for the presence of a B cell neoplasm

T cells

Develop from bone marrow, become prothymocytes, then migrate to thymus gland, where self-recognizing T cells are eliminated

T cell receptors (TCR) are either alpha/beta (95%) or gamma/delta (5%) heterodimers

Precursor cell is TdT+, CD34+, HLA-DR+, then drops HLA-DR, then adds CD2, CD5, CD7 (early thymocyte) while undergoing gamma/beta chain rearrangement, then adds CD1 and drops CD34, now a common thymocyte, then undergoes beta/alpha chain rearrangement and adds CD4 and CD8, then splits into helper or cytotoxic T cell, without TdT, CD1, CD5 and CD7; has CD2, CD3, CD4 (helper) or CD8 (cytotoxic)

T alpha and delta are on 14q11; T beta is on 7q34; T gamma is on 7p15 (note: there are only 10 V regions, so a polyclonal population of cells can appear oligoclonal)

90% of peripheral T-cell lymphomas have rearrangements of T-alpha, beta and gamma, including all cases of mycosis fungoides and Sezary syndrome

T cell lymphomas: no distinct marker of clonality, but cells may express an abnormal immunophenotype

Note: T cell clonality is seen in AIDS and congenital immunodeficiency syndromes, but does NOT indicate malignancy

Note: rarely a clonal band may comigrate with the germline band; solution - use 2-3 restriction enzymes (HindIII, EcoRI, BamHI)

Note: T cells and NK cells arise from common progenitor that expresses CD3 epsilon and cannot develop into B cells

NK cells

Distinct group of non-T, non-B lymphocytes; large granular lymphocyte morphology on Wright-Giemsa stains; capable of lysing certain target cells without prior activation or major histocompatibility complex restriction; believed important in defense against viral and bacterial infections and cancers as well as immunomodulation and regulation of hematopoiesis; comprise 5-20% of peripheral blood lymphocytes

Positive stains: CD56 (adhesion molecule), CD57 (unknown function), CD16 (low affinity IgG Fc receptor / FCRIII that is responsible for antibody dependent cellular cytotoxicity in NK cells and also expressed on neutrophils and monocyte subset); also cytoplasmic (not surface) CD3, CD2, CD7, CD8, perforin, granzyme B, TIA-1

>90% are CD16+/CD56+

Normal histology

Centroblasts: large non-cleaved follicular center cells with moderate amounts of basophilic cytoplasm, round nuclei, open chromatin, multiple peripheral nucleoli

Centrocytes: small cleaved follicular center cells with scant cytoplasm

Leukemia: lymphoid neoplasms that present with widespread bone marrow involvement and large numbers of tumor cells in the peripheral blood

Mantle zone: Small unchallenged B cells surrounding pale staining germinal centers

Marginal zone: light zone surrounding follicles; contain post-follicular memory B cells derived after stimulation of recirculating cells from T cell dependent antigen

Germinal center: strong dense bcl6 expression and CD10 expression

TdT: terminal deoxynucleotidyl transferase; marker for premature B and T cells

Note: antigen stimulated B cells with the capacity to differentiate toward plasma cells express MUM1/IRF4 and CD138

Molecular analysis

Fluorescent in-situ hybridization (FISH)

To identify and count chromosomes / parts of chromosomes,

Northern blot

To detect mRNA

Polymerase chain reaction (PCR)

10,000 times more sensitive than Southern blot

Clones appear as 1-2 bands (if 1 or 2 alleles were rearranged); polyclonal cells appear as a smear since no amplification usually occurs due to wide separation of V and J regions

Faster than Southern blot and minimal tissue required

Helpful for determining clonality of lymphoid aggregates in bone marrow biopsies (Archives 2000;124:511)

Procedure: add sample DNA, 4 nucleotides, buffer with magnesium, primers and Taq DNA polymerase to test tube; use PCR cycler with 3 reactions (#1 - denature double stranded DNA, #2 - allow annealing of primers, #3 - allow DNA polymerase activity to extend primer); multiple cycles allow exponential expansion of amount of DNA; analyze products by gel electrophoresis, then stain gel with ethidium bromide OR transfer gel to nylon membrane by Southern blotting and hybridize membrane with labeled probe

False negatives due to imperfect consensus primers, inability to detect partial DJ rearrangements; mutations of Ig genes that prevent annealing of primers; lymphomas that arise from B cell precursors prior to rearrangement

PCR + temperature gradient gel electrophoresis

To analyze T cell receptor gene rearrangement (Archives 2001;125:202)

Reverse transcriptase PCR (RT-PCR)

To detect chimeric fusion mRNA transcripts translocations

Southern blot

Detects DNA via restriction endonucleases, electrophoresis and probes

For lymphoma, detects alterations of DNA restriction fragment length from rearrangement of immunoglobulin and T cell receptor genes

Rearrangement forms a distinct band if only 1% of total cells are affected, so very sensitive; only a single germline band is present if polyclonal or not clonal

Difficult and slow to perform

Procedure: extract DNA, cut into small fragments with restriction enzymes (EcoRI, HindIII, BamHI); run on electrophoretic gel (agarose); apply nylon membrane (blot) over gel to transfer DNA fragments onto membrane; denature the probe DNA and DNA fixed to the blot to allow hybridization and add probe DNA; detect the probe (xray if probe radioactive); usually analyze IgH and TCR-beta for clonality

Theory of molecular analysis

B cells express surface immunoglobulin (Ig), composed of 2 heavy (H) and 2 light (L) chains (either kappa or gamma)

T cell receptors (TCR) are either alpha/beta (95%) or gamma/delta (5%) heterodimers

Ig and TCR germline configuration contains Variable, Diversity, Joining and Constant region segments

Early in normal lymphocyte differentiation within the bone marrow, the antigen receptor genes undergo recombination to create a variable region, containing an antigen combining site and a constant region. Diversity occurs through recombination of segments plus imprecise V-D-J joining

Terminal deoxytransferase (TdT) adds or removes nucleotides, causing even more diversity

Point mutations in V and J regions occurs commonly within Ig genes, adding to diversity

An estimated 100 million different Ig and TCRs exist

Rearrangement forms a distinct band if multiple cells have the same rearrangement pattern, indicating clonality

80% of B or T cell lymphomas with characteristic immunologic and clinical features have clonal IgH or TCR-gamma rearrangement by PCR (Mod Path 2000;13:1269); 10% of B cell and T cell lymphomas have both clonal IgH and TCR-gamma rearrangement

DD of “clonality”: non-neoplastic tissue may be clonal, perhaps due to autoimmune diseases for B cell disorders or granulomatous diseases for T cell disorders; tissue with a small number of polyclonal B cells (skin, GI) may cause a pseudoclonal PCR profile; best to do multiple PCR and look for same rearranged band in every experiment

References: Archives 1999;123:1189

Grossing lymph nodes

Best to obtain fresh and intact

Handle under sterile conditions for microbiology (depending on clinical history)

Use scrapes / cell suspension for flow cytometry, cytogenetics, molecular gene rearrangement studies, FISH

Obtain imprints for Wright stain or immunocytochemistry

Snap-freezing is best for research, some immunohistochemistry, future molecular studies

B5 (mercury containing fixative) provides best morphologic details

Formalin fixation is best for PCR

Use thin (2 mm) slices for proper fixation; cut perpendicular to long axis if possible

Include extranodal fat (infiltration implies malignant)

Features to report

Clinical history (prior diagnoses of lymphoma, presence of lymphadenopathy or organomegaly, hematologic findings, constitutional symptoms, HIV status, prior immune abnormality, autoimmune disorders, other relevant serology, other related conditions such as H. pylori infection)

Anatomic site

Tumor type(s) (WHO classification), grade (if relevant)

Focal or complete involvement of lymph node or other structures

Specimen inadequacy

Results of ancillary studies

References: Hum Path 2002;33:1064; Mod Path 2004;17:131

Non-Hodgkin Lymphoma

Non-Hodgkin lymphoma - general

Clonal lymphoproliferative disorder

Increasing incidence over past 40 years for unknown reasons

50,000 new cases in US per year, many HIV related

Heterogenous types of neoplasms; diagnosis of “NHL” gives far less information than type of NHL

Putative cell of origin known for most B cell NHLs but not most T cell NHLs

Often associated with a cytogenetic translocation that puts a proto-oncogene or apoptotic gene next to a gene that is constitutively active in lymphocytes

80% are B cell, NK are rare

All are monoclonal, as determined by antigen receptor gene rearrangement (immunoglobulin or T cell receptor)

Characteristic patterns of tissue involvement occur, such as follicular lymphomas in B cell areas, T cell lymphomas in paracortical zones

Most tumors are widely disseminated at diagnosis, requiring systemic therapy for cure; thus, staging is not as important as in Hodgkin lymphoma

In adults, most common subtypes are follicular lymphoma, diffuse large B cell lymphoma, CLL/SLL, multiple myeloma

Usually HER2 negative (Archives 2002;126:574)

Prognostic factors: see particular tumors; cyclin D3 overexpression identifies patients with indolent B cell lymphomas but adverse clinical features and poorer survival (AJCP 2001;115:404)

Risk factors: immunodeficiency (primary or secondary), autoimmune disorders (Sjogren’s, rheumatoid arthritis, Hashimoto’s thyroiditis), viruses (HIV, ATLV, KSHV/HHV8, HTLV-1), Helicobacter pylori infection, radiation, chemotherapy

Compared to Hodgkin lymphoma: more often extranodal, more often involve peripheral blood, bone marrow, GI, skin or CNS, more often disseminated, present with B symptoms less often (20% vs. 40%), less often mediastinal involvement (except for lymphoblastic and mediastinal large B cell lymphoma)

International Prognostic Index (IPI): poorer prognosis - age at diagnosis >60 years, presence of B symptoms, performance status 2-4 vs. 0-1, elevated serum LDH, more than 1 nodal or extranodal sites of disease, advanced vs. localized disease

DD: florid immunoblastic proliferations seen in infectious mononucleosis or other viral infections, particularly in children; autoimmune lymphoproliferative syndromes in patients in Fas or FasL deficiency may develop giant lymphadenopathy resembling EBV+ post-transplant lymphoproliferative disease (AJSP 1999;23:829)

Childhood NHL

Most common subtypes are Burkitt or Burkitt like, lymphoblastic leukemia/lymphoma, large cell lymphoma

Follicular and marginal zone lymphoma are uncommon

Usually extranodal, aggressive, often leukemic; better survival than adults

Fine needle aspiration

Sensitivity and specificity increase with flow cytometry; good in most lymphomas except marginal zone lymphoma and Hodgkin lymphoma

References: Archives 2000;124:1792

Classification Systems

Rappaport classification: 1956, revised 1966

Lukes and Collins classification, 1974

Working Formulation: 1982; tumors classified as low, intermediate or high grade; nodular vs. diffuse; small, large or mixed tumor cell size

Kiel classification: European system used in 1980-1990’s

REAL (Revised European American Lymphoma) / World Health Organization (WHO): integrates clinical, morphologic, immunohistochemical and molecular characteristics

Includes NHL, lymphocytic leukemias, plasma cell neoplasms; excludes histiocytic neoplasms

Tumors are not classified as low grade / high grade since one entity could have both types

High concordance under REAL between diagnoses in community hospital and academia; discordances seen for diffuse large cell lymphoma vs. Burkitt-like lymphoma, marginal zone lymphoma vs. another subtype, follicle center lymphoma grade II vs. grade III, Hodgkin lymphoma-nodular sclerosis vs. mixed cellularity (AJCP 2001;115:650)

Cytogenetics

Relatively common translocations (more complete lists are listed with each tumor)

t(1;14)(p22;q32): bcl-10 and IgH; MALT lymphoma (% unknown)

t(1;14)(p32;q11): SCL (tal-1) and T cell receptor delta/alpha; precursor T acute lymphoblastic leukemia (15-30%)

t(1;14)(q21;q32); bcl-9 and IgH; preB ALL, mantle cell lymphoma

t(1;19)(q23;p13): PBX1 and E2A; precursor B acute lymphoblastic leukemia (30%)

t(2;5)(p23;q35): ALK and NPM; anaplastic large cell lymphoma, T/NK subtypes (40-70%)

t(2;8)(p12;q24): Ig Kappa and c-myc; Burkitt lymphoma (15%)

t(2;18)(p12;q21): Ig Kappa and bcl2; follicular lymphoma (<5%)

Trisomy 3: MALT lymphoma (% unknown)

t(3;14)(q27;q32): bcl6 and IgH; diffuse large B cell lymphoma (30%), follicular lymphoma (10%)

t(4;11)(q21;q23): AF4 and MLL; precursor B acute lymphoblastic leukemia (10%)

t(4;14)(p16.3;q32): FGFR3/mmset and IgH; multiple myeloma (25-30%)

t(5;14): preB ALL and peripheral eosinophilia; IL3 gene and IgH

t(6;14)(p25;q32) - mum/irf4 and IgH; multiple myeloma

7q isochromosome: protein unknown, hepatosplenic gamma/delta lymphoma (% unknown)

Trisomy 8: protein unknown, hepatosplenic gamma/delta lymphoma (% unknown)

t(8;13)(p11;q11-12): FGFR1 and ZNF 198; T cell lymphoblastic with eosinophilia (% unknown)

t(8;14)(q24;q32): c-myc and IgH; Burkitt lymphoma (75%), acute lymphocytic leukemia-type L3 (6%)

t(8;21): ETO gene and AML1 gene; AML-M2

t(8;22)(q24;q11): c-myc and Ig Lambda; Burkitt lymphoma (10%)

9p amplification: REL; primary mediastinal large B cell lymphoma (% unknown)

t(9;14)(p13;q32): PAX5 and IgH; lymphoplasmacytic lymphoma (% unknown)

t(9;22)(q34;q11): c-abl and bcr (Philadelphia chromosome); precursor B acute lymphoblastic leukemia

(5% of children, 25% of adults), chronic myelogenous leukemia (100%)

t(10;14)(q24;q11): HOX11 and T cell receptor delta/alpha; precursor T acute lymphoblastic leukemia (7%)

deletion of 11q23: CLL (10-20%)

t(11;14)(q13;q32): bcl-1/PRAD1 and IgH; mantle cell lymphoma (90%), B cell prolymphocytic leukemia (20%), myeloma (3%)

t(11;14): T-ALL; rhombotin 1/2 genes and IgH

t(11;18)(q21;q21): API2 and MLT; MALT lymphoma (50%)

Trisomy 12: protein unknown, B chronic lymphocytic leukemia (30%)

t(12;21)(p13;q22): ETV6-CBFA2 (TEL and AML1); Precursor B acute lymphoblastic leukemia (20%)

deletion 13q14: protein unknown; B cell CLL (25-50%)

inversion 14(q11;q32) or other #14 translocations: T cell prolymphocytic leukemia (75%)

t(14;15)(q32;q11-13); IgH and bcl-8; diffuse large B cell lymphoma (3%)

t(14;16)(q32;q23); IgH and c-maf; multiple myeloma

t(14;18)(q32;q21): IgH and bcl2; follicular lymphoma (90%), diffuse large B cell lymphoma (30%)

t(14;19)(q32;q13): IgH and bcl-3; B cell CLL

t(15;17): retinoic acid receptor and PML gene; acute prolymphocytic leukemia, M3 (most)

t(16;22);(q23;q11): cmaf and Ig lambda; multiple myeloma

Trisomy 18: common in marginal zone lymphoma, MALT type

Staging of Non-Hodgkin lymphomas

I: one anatomic region or two contiguous regions on same side of diaphragm

II: two or more anatomic regions or noncontiguous regions on same side of diaphragm

III: both sides of diaphragm, but lymph nodes or spleen only

IV: any lymph node region plus liver, lung or bone marrow

National Cancer Institute Modified Staging for Intermediate and High Grade Lymphomas

I: Localized disease (nodal or extranodal)

II: Two or more nodal sites or a localized extranodal site plus draining sites plus either performance status <=70, B symptoms, any mass > 10 cm, serum LDH > 500, 3 or more extranodal sites of disease

III: Stage II and any poor prognostic factor

Morphologic clues to diagnosis

Small cells, round: CLL/SLL

Small / intermediate cells with atypia: Mantle cell lymphoma (irregular), MALT lymphoma (monocytoid)

Intermediate cells: follicular lymphoma (cleaved), Burkitt lymphoma (non-cleaved, prominent nucleoli), lymphoblastic lymphoma (fine chromatin)

Large cells: diffuse large B cell lymphoma, mycosis fungoides or Sezary syndrome (cerebriform), anaplastic large cell lymphoma (pleomorphic)

Hemophagocytic syndrome

May be associated with non-Hodgkin lymphoma (most common: diffuse large B cell, T cell, NK)

Systemic presentation (fever, splenomegaly, jaundice), survival < 2 years, mild interstitial lymphoid infiltrate of bone marrow at presentation (AJSP 2001;25:865)

Treatment: cytotoxic chemotherapy if EBV related vs. treatment of infection in non-EBV infection

Gross: often no pronounced tumor mass

Micro: hemophagocytosis (phagocytosis by macrophages of white blood cells, red blood cells, platelets and precursors); in bone marrow, mild interstitial lymphoid infiltrate at presentation

Positive stains: depends on tumor type

Molecular: occasional HHV6 positive by PCR

Chemotherapeutic atypia

Chemotherapeutic agents, particularly alkylating agents, can induce bizarre epithelial atypia

Observed in lower respiratory tract and sinonasal tract

Includes patients treated for leukemia, myeloma

Micro: striking nuclear enlargement, hyperchromasia and pleomorphism

DD: dysplasia, particularly in frozen sections (AJSP 2001;25:652)

B cell disorders

B cell disorders – general

Almost always surface Ig light chain positive

After rituximab therapy (anti-CD20 monoclonal antibody), bone marrow specimens contain aggregates of T cells that suggest relapse; thus, ordering immunostains is important (AJCP 1999;112:844)

Low grade tumors may have extensive sarcoid-like granulomas (Archives 2000;124:152)

B cell non-Hodgkin lymphomas rarely are CD2+, but behavior is similar to CD2- tumors; must differentiate from composite B, T cell lymphomas (AJCP 2001;115:396)

WHO classification of B cell lymphoid neoplasms

Precursor B cell neoplasms:

Precursor B lymphoblastic leukemia/lymphoma

Mature (peripheral) B cell neoplasms:

Chronic lymphocytic leukemia/small lymphocytic lymphoma

B cell prolymphocytic leukemia

Lymphoplasmacytic lymphoma / Waldenstrom macroglobulinemia

Splenic marginal zone B-cell lymphoma

Hairy cell leukemia

Extranodal marginal zone B-cell lymphoma of MALT type

Nodal marginal zone B-cell lymphoma

Follicular lymphoma

Mantle cell lymphoma

Diffuse large B cell lymphoma

Mediastinal (thymic) large B cell lymphoma

Intravascular large B cell lymphoma

Primary effusion lymphoma

Burkitt lymphoma/leukemia

Lymphomatoid granulomatosis

Histologic Types

Burkitt lymphoma

30% of childhood lymphomas, may present as B cell acute lymphoblastic leukemia FAB L3 (also called Burkitt leukemia)

Either endemic, sporadic or immunodeficiency-associated

In adults, often associated with immunodeficiency, including HIV; involves distal ileum, cecum, mesentery

In Africa, involves jaw or abdomen (endemic), 95% are EBV positive; malaria may facilitate EBV infection

Curable with aggressive therapy in 60%

Due to c-myc translocation that causes increased constitutive levels of c-myc

Micro: diffuse infiltration of monomorphic, medium-sized (10-25 micron) cells with abundant basophilic cytoplasm, non-cleaved round nuclei with coarse chromatin and 2-5 distinct nucleoli; mitotically active with starry sky pattern (stars are tingible body macrophages)

Imprints demonstrate cytoplasmic lipid vacuoles; rarely granulomas (AJSP 2004;28:379)

Positive stains: CD10, CD19, CD20, Ki-67 (almost 100%), surface immunoglobulin; also CD22, CD79a, bcl2, bcl6, surface IgM; EBV positive in endemic African cases and AIDS cases

Negative stains: CD5, CD23, TdT

Molecular: c-myc translocations:

t(8;14)(q24;q32): c-myc and IgH (75%); also reported in some diffuse large B cell lymphomas

t(2;8)(p12;q24): Ig Kappa and c-myc (15%)

t(8;22)(q24;q11): c-myc and Ig Lambda (10%)

DD: diffuse large B cell lymphoma with c-myc translocation (Ki-67+ in 67% vs. 100% in Burkitt’s, Mod Path 2002;15:771)

References: Archives 2004;128:549 (EBV in endemic Burkitt)

CD5+ Burkitt leukemia

Elderly patients with leukemic tumor cells resembling Burkitt lymphoma by morphology and immunostains

DD: blastoid variant of mantle cell lymphoma (c-myc neg, cyclin D1+, AJCP 1999;112:828)

Burkitt-like lymphoma (atypical Burkitt)

Usually adults

Micro: cellular pleomorphism and heterogeneity intermediate between Burkitt and diffuse large cell lymphoma

Positive stains: >95% Ki-67+

Negative stains: CD10, c-myc (usually)

Chronic lymphocytic leukemia/small lymphocytic lymphoma [B cell type]

Also called CLL/SLL

Most common adult leukemia in Western countries, less common in Japan/Asia

Usually older patients (median age 60), 2/3 male, with disease in bone marrow, lymph nodes, spleen, liver

Often presents with leukemia although patients may be asymptomatic

Median survival 4-6 years; indolent but incurable

Associated with hypogammaglobulinemia, monoclonal immunoglobulin spikes in some, infections, autoantibodies to red blood cells and platelets with resulting hemolytic anemia and thrombocytopenia

Often converts to high grade neoplasm via prolymphocytic transformation (20%) or Richter’s syndrome (10%)

Prolymphocytic transformation causes death within median 2 years

Richter syndrome with transformation to diffuse large cell lymphoma retains CLL phenotype (AJCP 2001;115:385) but causes death within median 5 months; Richter syndrome cases with EBV+ Hodgkin’s lymphoma features may have distinct clonal origin (AJSP 2004;28:679)

Primary digestive tract Richter’s syndrome is associated with longer survival (median 22 months) after chemotherapy (Mod Path 2001;14:452)

Rarely transforms to aggressive T cell or NK cell lymphoma with cytotoxic immunophenotype (AJSP 2004;28:849)

Diagnosis: absolute lymphocyte count of 4000 or more in peripheral blood is suggestive

Poor prognostic factors: 17p deletions, 11q22-23 deletion, non-mutated immunoglobulin genes

Case reports: CLL with composite prolymphocytoid and Hodgkin’s transformation (Archives 2000;124:907), CLL with composite thymoma (Archives 2003;127:E76), filamentous cytoplasm inclusions in peripheral blood due to dilated cisternae of rough endoplasmic reticulum containing IgG (Archives 2003;127:618), cases with t(14;18) (Archives 2002;126:1543)

Gross: nodes identified at prostatectomy are enlarged (mean 3.2 cm)

Micro: effacement of nodal architecture by pale staining pseudofollicles or proliferation centers with ill-defined borders, containing small round mature lymphocytes, prolymphocytes (larger than small lymphocytes, abundant basophilic cytoplasm, prominent nucleoli), paraimmunoblasts (larger cells with distinct nucleoli) and many smudge cells

Pseudofollicular centers are highlighted by decreasing light through the condenser at low power; cells have pale cytoplasm but resemble soccer balls or smudge cells on peripheral smear vs. bubbly cytoplasm in mantle cell lymphoma; may have plasmacytoid features

CLL/prolymphocytic leukemia: 10-55% prolymphocytes

Prolymphocytic leukemia: >55% prolymphocytes

Bone marrow involvement is interstitial, not paratrabecular

Other patterns are marginal zone, nodular, perifollicular and interfollicular (see below)

Positive stains: CD5, CD19, CD20 (dim), CD23, surface IgM (dim); also CD43, CD79a, CD79b (dim, in 20%), bcl2; variable CD11c

Negative stains: CD10, cyclin D1; also CD79b, FMC-7 (80% are negative)

Molecular: Trisomy 12 (30%, associated with atypical CLL and CD79b), deletion 13q14 (25-50%), deletion of 11q23 (worse prognosis, 10-20%)

DD: other low grade lymphomas with leukemic phase (mantle cell lymphoma, follicular lymphoma, rarely lymphoblastic lymphoma), Hodgkin’s lymphoma, peripheral T cell lymphoma, reactive hyperplasia, persistent polyclonal B cell lymphocytosis (Mod Path 2004 May 14)

References: AJSP 2004;28:801 (new cyclin D1 antibody), Archives 2003;127:561 (CD79b), Archives 2003;127:567 (incidental findings at prostatectomy), Mod Path 2002;15:1111 (resembles leukemic phase of mantle cell or follicular lymphoma)

Variants:

CD5 negative B-cell CLL

Probably is NOT CLL

Have adhesion molecular profiles resembling leukemic non-Hodgkin lymphoma but different from CD5+ B-cell CLL (Hum Path 2001;32:66)

Patients older with more advanced disease and lower absolute lymphocyte counts than CD5+ B-cell CLL (AJCP 1999;111:477)

Interfollicular pattern

Large, reactive germinal centers by definition

Resembles follicular lymphoma but germinal centers are bcl2 negative and tumor cells resemble CLL/SLL by histology (small round lymphoid cells with proliferation centers) and immunostains (CD5+, CD23+), AJCP 2000;114:41

Paraimmunoblastic variant

Rare, <30 reported cases

Usually multiple lymphadenopathies and rapid disease progression

Case report in 69 year old man (Hum Path 2002;33:1145)

Micro: diffuse proliferation of paraimmunoblasts (normally just in pseudoproliferation centers)

Molecular: consider as mantle cell lymphoma if t(11;14)(q13;q32) is present

DD: large cell variant of mantle cell lymphoma, CD5+ diffuse large B cell lymphoma

Diffuse large B cell lymphoma

Common in Western countries

Variants described separately are: intravascular, lymphomatoid granulosis, mediastinal, primary cutaneous, primary effusion

All ages, 30%-40% are extranodal (skin, bone, gastrointestinal, genitourinary, CNS); 50% are stage III/IV at diagnosis

Often single, rapidly growing mass; may be in liver, spleen; bone marrow involvement typically late

Fatal if untreated; remission in 70% after chemotherapy, 50% cure rate

Often difficult to diagnose on flow cytometry

Either germinal center B-like (bcl6+, CD10+, CD38+), activated B-like (IRF4+, FLIP+, bcl2+), or neither

1/3 arise from transformation of follicular lymphoma (germinal center like), detectable by bcl2 rearrangement or bcl6/CD10 coexpression with strong and uniform bcl6 expression

Prognosis: Better if limited disease, favorable international prognostic index; better if germinal center gene expression profiles [documented as bcl6+ or (CD10+ or bcl6+ AND negative for MUM1/IRF4 and CD138) vs. activated B cell-like; poorer if p53 mutations present; poorer if CD10+ and bcl2+ by flow cytometry (AJCP 2001;116:183)

Case reports: associated with Hepatitis C (Archives 2000;124:1532), ALK+ but CD30- tumors (AJSP 2003;27:1473; Mod Path 2003;16:828); exhibiting Homer-Wright type rosettes (Archives 2003;127:e411); ovarian tumor with spindle cell morphology (Archives 2003;127:e169); see also AIDS associated

Micro: diffuse growth pattern with large cells (5 x normal lymphocytes) resembling immunoblasts (amphophilic cytoplasm, eccentric nuclei with one central nucleoli) or centroblasts (pale or basophilic cytoplasm, vesicular chromatin due to chromatin margination, 2-3 nucleoli, often near membrane), associated with neutrophils (Archives 2000;124:735); may have plasmacytic differentiation or epithelioid granulomas (Mod Path 2002;15:750)

ALK+: immunoblastic cells with intravascular growth pattern, ALK+, CD30-, often extensive necrosis

Anaplastic: resembles anaplastic large cell lymphoma or metastatic carcinoma

Microvillous: sinus growth pattern with surface villi by EM

T cell/histiocyte rich: see below

Positive stains: CD19, CD20, CD22, CD79a; also CD10 (if follicular origin); variable CD45, variable surface Ig, variable bcl2; in Korea 1/3 are bcl6+/CD10+ (Hum Path 2001;32:954)

Negative stains: TdT, variable CD5, cytokeratin (rarely are positive, Archives 2001;125:1104)

Molecular: IgH and IgL are clonally rearranged, but may be difficult to document in T cell rich cases

t(14;18)(q32;q21): IgH and bcl2 in 30%, also in follicular lymphoma

t(3;14)(p27;q32): bcl6 and IgH in 30%, also in follicular lymphoma

Numerous other translocations involving bcl6 (3q27)

DD: carcinoma (including nasopharyngeal), melanoma, seminoma/dysgerminoma, granulocytic sarcoma, thymoma, infectious mononucleosis or other childhood viral infections

References: AJSP 2004;28:464 (stains as prognostic factors); Mod Path 2002;15:413 (CD10: flow vs. immunostains); Mod Path 2003;16:471 (bcl6 and CD10 and apoptosis/proliferation)

CD5+ diffuse large B cell lymphoma

5% of diffuse large B cell lymphomas, with diffuse splenic red pulp involvement, mantle cell like pattern (CD23-, FMC7+), or other

Overall, most do NOT appear related to CLL/SLL or mantle cell lymphoma (AJCP 2000;114:523)

T cell/histiocyte rich diffuse large B cell lymphoma

Usually older adults, often with advanced stage and involvement of lymph nodes, spleen, bone marrow

Morphologic variants include L&H like, centroblast/immunoblasts and Reed-Sternberg like

L&H like cases may be related to nodular lymphocyte predominant Hodgkin lymphoma

Case report of CD5+ tumor (Mod Path 2002;15:1051)

Micro: diffuse growth of neoplastic large B cells (<10% of cells) scattered within small reactive T cells and histiocytes, in fine fibrillary fibrous background

L&H like: pale and indistinct cytoplasm, lobated and vesicular nuclei resembling popcorn cells with small central nucleoli, background of small lymphocytes and often histiocytes, no granulomas