Lymph Nodes

Abstract

Fine needle aspiration and small tissue biopsies have become a popular modality for an initial workup or to achieve a definitive diagnosis of a patient with lymphadenopathy. This chapter delineated cytologic and histologic features of common and rare neoplastic and nonneoplastic lesions of the lymph node. The utilities and pitfalls of commonly used diagnostic immunohistochemical (IHC) stains such as PAX5, LEF1, LMO2, and SOX11, and small diagnostic IHC panels, and flow cytometry were described. Multiple challenging and yet practical cases at the end of the chapter were used to re-emphasize important points illustrated throughout the chapter.

FormalPara Summary of Pearls and Pitfalls

• Always attempt to get sufficient sample for flow cytometric study, molecular analysis, and cellblock preparation if a lymphoma is suspected.

• A final diagnosis of lymphoma should not be based on cytomorphology alone. Ancillary tests such as flow cytometric study, immunohistochemistry (IHC), and cytogenetic analysis/fluorescence in situ hybridization (FISH) should be performed.

• Cell block preparation for immunostains is highly recommended if large B-cell lymphoma (LBCL) is suspected, since a significant number of cases have an inconclusive diagnosis from flow cytometric analysis due to the breakdown of the cytoplasm of lymphoid cells.

• Incisional or excisional biopsy is recommended for all cases suspicious for Hodgkin lymphoma , T-cell lymphoma , T-cell-rich B-cell lymphoma, transformation from a low-grade lymphoma into a high-grade non-Hodgkin lymphoma and unusual types of lymphoma.

• Culture should be considered when acute inflammation and necrosis are present.

• Mycobacterial infection should be considered when a granulomatous process and necrosis are present.

• Cohesive sheets and groups of lymphoid cells are frequently seen in an LBCL that might be mistaken for metastatic carcinoma .

• Noncaseating granulomas are frequently seen in Hodgkin lymphoma and T-cell lymphoma, in addition to benign conditions and metastatic tumors, such as seminoma.

• In addition to Burkitt lymphoma (BL), cytoplasmic vacuoles can be seen in other high-grade lymphomas, rhabdomyosarcoma, seminoma, and carcinomas.

• Lymphoglandular bodies are less frequently present in plasmacytoma or myeloid sarcoma .

• HIV-associated follicular hyperplasia and mononucleosis are more likely to mimic a high-grade lymphoma.

• Collision tumors, such as metastatic small cell carcinoma or melanoma in the background of small lymphocytic lymphoma (SLL), are infrequent, but can be seen.

• Most low-grade lymphomas have a mindbomb homolog 1 (MIB-1, Ki-67) proliferative index less than 26%; in contrast, high-grade lymphoma usually has a MIB-1 proliferative index greater than 26%.

2017 WHO Classification of Mature Lymphoid , Histiocytic, and Dendritic Neoplasms

Used with permission from Arber et al. (Arber et al. 2016); and from Swerdlow et al. (Swerdlow et al. 2016a).

Mature B-Cell Neoplasms

• Chronic lymphocytic leukemia /small lymphocytic lymphoma (CLL/SLL)

• Monoclonal B-cell lymphocytosis¹

• B-cell prolymphocytic leukemia

• Splenic marginal zone lymphoma (MZL )

• Hairy cell leukemia

• Splenic B-cell lymphoma/leukemia, unclassifiable

  • Splenic diffuse red pulp small B-cell lymphoma

  • Hairy cell leukemia variant

• Lymphoplasmacytic lymphoma (LPL)

  • Waldenström macroglobulinemia

• Monoclonal gammopathy of undetermined significance (MGUS), IgM²

• Mu heavy chain disease

• Gamma heavy chain disease

• Alpha heavy chain disease

• MGUS, IgG/A²

• Plasma cell myeloma

• Solitary plasmacytoma of the bone

• Extraosseous plasmacytoma

• Monoclonal immunoglobulin deposition diseases³

• Extranodal MZL of mucosa-associated lymphoid tissue (MALT lymphoma)

• Nodal MZL

  • Pediatric nodal MZL

• Follicular lymphoma

  • In situ follicular neoplasia³

  • Duodenal-type follicular lymphoma³

• Pediatric-type follicular lymphoma³

• LBCL with interferon regulatory factor 4 (IRF4) rearrangement ³

• Primary cutaneous follicle center lymphoma

• Mantle cell lymphoma (MCL )

  • In situ mantle cell neoplasia³

• Diffuse large B-cell lymphoma (DLBCL ), not otherwise specified (NOS)

  • Germinal center B-cell type³

  • Activated B-cell (ABC) type³

• T-cell/histiocyte-rich LBCL

• Primary DLBCL of the central nervous system (CNS)

• Primary cutaneous DLBCL , leg type

• Epstein-Barr virus (EBV )-positive DLBCL , NOS³

• EBV + mucocutaneous ulcer ⁴

• DLBCL associated with chronic inflammation

• Lymphomatoid granulomatosis

• Primary mediastinal (thymic) LBCL

• Intravascular LBCL

• ALK-positive LBCL

• Plasmablastic lymphoma

• Primary effusion lymphoma

• Human herpes virus 8 (HHV8)-positive DLBCL , NOS ⁴

• Burkitt lymphoma

• Burkitt-like lymphoma with 11q aberration ⁴

• High-grade B-cell lymphoma (HGBCL), with MYC and BCL2 and/or BCL6 rearrangements⁴

• HGBCL, NOS⁴

• B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and CHL

Mature T- and Natural Killer (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 + T-cell lymphoma of childhood⁴

• Hydroa vacciniforme-like lymphoproliferative disorder⁵

• Adult T-cell leukemia/lymphoma

• Extranodal NK/T-cell lymphoma , nasal type

• Enteropathy-associated T-cell lymphoma

• Monomorphic epitheliotropic intestinal T-cell lymphoma⁵

• Indolent T-cell lymphoproliferative disorder of the gastrointestinal (GI) tract ⁵

• Hepatosplenic T-cell lymphoma

• Subcutaneous panniculitis-like T-cell lymphoma

• Mycosis fungoides

• Sézary syndrome

• Primary cutaneous CD30 -positive T-cell lymphoproliferative disorders

  • Lymphomatoid papulosis

  • Primary cutaneous anaplastic large cell lymphoma

• Primary cutaneous gamma-delta T-cell lymphoma

• Primary cutaneous CD8 -positive aggressive epidermotropic cytotoxic T-cell lymphoma

• Primary cutaneous acral CD8 -positive T-cell lymphoma ⁵

• Primary cutaneous CD4 -positive small/medium T-cell lymphoproliferative disorder ⁵

• Peripheral T-cell lymphoma, NOS

• Angioimmunoblastic T-cell lymphoma

• Follicular T-cell lymphoma ⁵

• Nodal peripheral T-cell lymphoma with T follicular helper (TFH) phenotype ⁶

• Anaplastic large cell lymphoma, ALK positive

• Anaplastic large cell lymphoma, ALK negative⁶

• Breast implant-associated ALCL ⁶

Hodgkin Lymphoma

• Nodular lymphocyte-predominant Hodgkin lymphoma

• Classical Hodgkin lymphoma (CHL)

  • Nodular sclerosis CHL

  • Lymphocyte-rich CHL

  • Mixed cellularity CHL

  • Lymphocyte-depleted CHL

Posttransplant Lymphoproliferative Disorders (PTLD )

• Plasmacytic hyperplasia PTLD

• Infectious mononucleosis PTLD

• Florid follicular hyperplasia PTLD⁶

• Polymorphic PTLD

• Monomorphic PTLD (B- and T-/NK-cell types)

• CHL PTLD

Histiocytic and Dendritic Cell Neoplasms

• Histiocytic sarcoma

• Langerhans cell histiocytosis (LCH )

• Langerhans cell sarcoma

• Indeterminate dendritic cell tumor

• Interdigitating dendritic cell sarcoma

• Follicular dendritic cell sarcoma

• Fibroblastic reticular cell tumor

• Disseminated juvenile xanthogranuloma

• Erdheim-Chester disease⁶

B Lymphoblastic Leukemia /Lymphoma

• B lymphoblastic leukemia/lymphoma, NOS

• B lymphoblastic leukemia/lymphoma with recurrent genetic abnormalities

• B lymphoblastic leukemia/lymphoma with t(9;22)(q34.1;q11.2); BCR-ABL1B lymphoblastic leukemia/lymphoma with t(v;11q23.3); KMT2A rearranged

• B lymphoblastic leukemia/lymphoma with t(12;21)(p13.2;q22.1); ETV6-RUNX1

• B lymphoblastic leukemia/lymphoma with hyperdiploidy

• B lymphoblastic leukemia/lymphoma with hypodiploidy

• B lymphoblastic leukemia/lymphoma with t(5;14)(q31.1;q32.3) IL3-IGH

• B lymphoblastic leukemia/lymphoma with t(1;19)(q23;p13.3); TCF3-PBX1

• Provisional entity: B lymphoblastic leukemia/lymphoma, BCR-ABL1-like

• Provisional entity: B lymphoblastic leukemia/lymphoma with iAMP21

T Lymphoblastic Leukemia/Lymphoma

Provisional entity: early T-cell precursor lymphoblastic leukemia

Provisional entity: NK-cell lymphoblastic leukemia/lymphoma

Nonneoplastic Lymph Nod es

Cytological Features (Fig. 4.1a, b)

• High cellularity

• Mixed population of lymphoid cells with small lymphocytes predominant

• Plasma cells, plasmacytoid cells, and immunoblasts

• Histiocytes and tingible-body macrophages

Fig. 4.1

(a, b) Reactive lymph node with a mixed population of lymphoid cells with small lymphocytes predominant on Diff-Quik (a) and Pap stain (b)

Suppurative Lymphadenitis

Cytological Features (Fig. 4.2a, b)

• Mixed population of lymphoid cells with a variable number of neutrophils.

• Degenerated lymphoid cells, histiocytes, neutrophils, and necrotic debris.

• Bacteria or fungus may be seen.

• Etiologies could include cat-scratch disease, bacterial infection, lupus, and less commonly Hodgkin lymphoma and metastatic carcinomas.

Fig. 4.2

(a, b) Suppurative lymphadenitis with degenerated lymphoid cells, histiocytes, neutrophils, and necrotic debris on Diff-Quik (a) and Pap stain (b)

Histologic Features

• Preserved nodal architecture with lymphoid follicular hyperplasia (Fig. 4.3).

  Fig. 4.3

  

  Suppurative lymphadenitis showing preserved nodal architecture with reactive lymphoid follicles and focal abscess formation

• Hyperplastic lymphoid follicles show polarity with tingible-body macrophages (Fig. 4.4).

  Fig. 4.4

  

  Reactive lymphoid follicles with polarity and tingible-body macrophages

• Increased neutrophilic infiltrate, abscess formation, and perilymphadenitis (Fig. 4.5).

  Fig. 4.5

  

  Suppurative lymphadenitis with focal abscess formation and necrosis

Infectious Mononucleosis

Cytological Features

• Highly cellular specimen

• Mixed population of lymphoid cells with many immunoblasts and plasmacytoid cells.

• Large atypical lymphoid cells are frequently present; some may mimic Hodgkin cells.

• Flow cytometry reveals an abundance of CD8 -positive T cells and only a small population of B cells.

Histologic Features

• Preserved nodal architecture with paracortical expansion composed of mixed mature lymphocytes, plasma cells, immunoblasts, and histiocytes in a mottled pattern (Figs. 4.6 and 4.7)

  Fig. 4.6

  

  Infectious mononucleosis with reactive lymphoid follicles and perifollicular expansion

  Fig. 4.7

  

  Infectious mononucleosis with lymphoblasts and immunoblasts showing prominent nucleoli

• Lymphoid follicular hyperplasia

• EBV -positive by in situ hybridization stain (Fig. 4.8)

  Fig. 4.8

  

  Infectious mononucleosis with positive EBV by in situ hybridization stain

Differential Diagnosis

• HGBCL

• Hodgkin lymphoma

Rosai-Dorfman Diseas e

Cytological Features

• Mixed population of lymphoid cells.

• A large number of histiocytes with pale cytoplasm.

• Many histiocytes contain lymphoid cells or red blood cells.

• These histiocytes are positive for S100, but negative for CD1a .

• Tissue biopsy should be recommended for a final diagnosis.

Histologic Features

• Marked sinus dilatation with sheets of foamy histiocytes (Figs. 4.9 and 4.10).

  Fig. 4.9

  

  Lymph node with Rosai-Dorfman disease shows marked sinus dilation

  Fig. 4.10

  

  Lymph node with Rosai-Dorfman disease shows sheets of histiocytes

• Some histiocytes may contain lymphocytes, plasma cells, or red blood cells.

Granulomatous Lymphadenitis

Cytological Features (Fig. 4.11a–c)

• Mixed population of lymphoid cells.

• Epithelioid histiocytes in aggregates with or without multinucleated giant cells.

• Necrotic debris and acute inflammatory cells may or may not be present.

• Etiologies could include foreign body reaction, sarcoidosis, fungus, mycobacteria, and toxoplasmic lymphadenitis.

• Culture should be submitted.

Fig. 4.11

(a–c) Granulomatous lymphadenitis with epithelioid histiocytes in aggregates with or without multinucleated giant cells and a mixed population of lymphoid cells on Diff-Quik (a), Pap stain (b), and cellblock preparation (c)

Histologic Features

• Granulomas with necrosis in infection of mycobacteria (Figs. 4.12, 4.13, and 4.14)

  Fig. 4.12

  

  Lymph node with caseating granulomas in tuberculosis

  Fig. 4.13

  

  Lymph node with caseating granulomas showing necrosis and giant cells

  Fig. 4.14

  

  Special stain (acid-fast bacilli [AFB], acid-fast Fite) reveals mycobacteria in caseating granulomas

• Granulomas surrounded by few or no lymphocytes (naked granuloma) in sarcoidosis (Figs. 4.15, 4.16, 4.17, and 4.18)

  Fig. 4.15

  

  Sarcoidosis in lymph node with noncaseating granulomas

  Fig. 4.16

  

  Sarcoidosis in lymph node with “naked” noncaseating granulomas

  Fig. 4.17

  

  Sarcoidosis in the spleen with noncaseating granulomas

  Fig. 4.18

  

  Sarcoidosis in the spleen with “naked” noncaseating granulomas

• Epithelioid granuloma and sheets of monocytoid lymphocytes in infection of Toxoplasma (Figs. 4.19 and 4.20)

  Fig. 4.19

  

  Lymph node with toxoplasma shows reactive lymphoid follicles and expanded perifollicular area in a “mottled” appearance

  Fig. 4.20

  

  Lymph node with toxoplasma shows cluster of epithelioid histiocytes and monocytoid lymphocytes

• Multinucleated cells with foreign body in foreign body granuloma (Fig. 4.21)

  Fig. 4.21

  

  Foreign body granuloma with giant cells containing foreign body (arrow)

Non-Hodgkin Lymphoma s

Cytological Features

• Hypercellular specimen

• A relatively uniform population of lymphoid cells

• Can be divided into three groups

• Group 1 – small lymphoid cells (smaller than histiocytes), such as small lymphocytic lymphoma (SLL), grade I follicular lymphoma, MZL , LPL

• Group 2 –intermediate lymphoid cells (same size as histiocytes), such as MCL , grade II follicular lymphoma, BL, lymphoblastic lymphoma

• Group 3 – large lymphoid cells (larger than histiocytes), such as LBCL, grade III follicular lymphoma, ALCL , some T-cell lymphomas

• Immunophenotypes of B-cell lymphoma (Table 4.1) and frequent chromosomal translocations and gene mutations (Tables 4.2 and 4.3)

  Table 4.1 Immunophenotype of B-cell lymphomas

  Table 4.2 Summary of chromosomal translocation-associated lymphomas and the affected genes

  Table 4.3 Most common gene mutations in non-Hodgkin lymphomas

Small Lymphocytic Lymphoma (SLL)

Clinical Features

• Rare before 40 years of age

• General lymphadenopathy

• Bone marrow involvement

Cytological Features (Fig. 4.22a, b)

• Highly cellular

• Monotonous population of small lymphocytes

• Smooth nuclear membrane, “clock face” nuclear chromatin, small to invisible nucleoli, and scant cytoplasm

Fig. 4.22

(a, b) Small lymphocytic lymphoma with monotonous population of small lymphocytes on Diff-Quik (a) and Pap stain (b)

Histologic Features

• Effaced nodal architecture in a vaguely nodular (pseudofollicular) pattern (Fig. 4.23).

  Fig. 4.23

  

  Small lymphocytic lymphoma with effaced nodal architecture in a vaguely nodular (pseudofollicular) pattern

• Sheets of neoplastic lymphocytes with hypercondensed chromatin and round to slightly irregular nuclear contour (Fig. 4.24).

  Fig. 4.24

  

  Small lymphocytic lymphoma cells with hypercondensed chromatin and round nuclear contour; admixed prolymphocytes (arrow) with nucleolus and larger in size

• Admixed with prolymphocytes.

• Adenopathy <1.5 cm by computed tomography (CT) scan is called tissue-based monoclonal B-cell lymphocytosis.

Immunohistochemistry and Ancillary Studies

• Flow cytometry studies: CD19+, CD20 + (low intensity), CD5 +, CD23 +, CD43 +, FMC7- (Fig. 4.25a–d); CD38 and zeta-chain-associated protein kinase 70 (ZAP-70 ) to evaluate the prognosis: both negative, most favorable; one positive and one negative, intermediate; and both positive, least favorable prognosis

  Fig. 4.25

  

  (a–d) Flow cytometry studies in small lymphocytic lymphoma shows CD19+ lymphoma cells with coexpression of CD5 and CD23 , positive for CD43 and negative for FMC7

• IHC: CD20 +, PAX5 + (especially important after Rituxan treatment that cause CD20 negativity on IHC), CD5 +, CD23 +, lymphoid enhancer-binding factor 1 (LEF1 )+ (Fig. 4.26)

  Fig. 4.26

  

  Small lymphocytic lymphoma positive for LEF1

• FISH: deletion of 13q14 in 50% of cases, trisomy 12 in 20% of cases (Figs. 4.27 and 4.28)

  Fig. 4.27

  

  FISH in small lymphocytic lymphoma with deletion of 13q14 (IR2G2A) in 50% of cases

  Fig. 4.28

  

  FISH in small lymphocytic lymphoma with trisomy 12 (2R3G2A) in 20% of cases

Differential Diagnosis

• Reactive lymph node

• Other low-grade lymphoma

Follicular Lymphoma

Clinical Features

• Accounts for 35% of adult non-Hodgkin lymphomas in the USA and 22% worldwide.

• Accounts for 70% of “low-grade” lymphomas in the USA.

• Affecting mainly adults, median age of 59 years, rarely occurs before age 20 years.

• 40% of patients have bone marrow involvement at the initial diagnosis.

Cytological Features (Fig. 4.29a–d)

• Usually cellular.

• Small lymphocytes with cleaved nuclei.

• Papanicolaou (Pap) stain better shows nuclear membrane irregularities.

• Small to inconspicuous nucleoli and scant cytoplasm.

• Increased numbers of large atypical lymphoid cells (centroblasts) in grade 2 and grade 3 follicular lymphoma.

• Grading of follicular lymphoma in a fine needle aspiration (FNA) specimen is similar to that of a histological specimen by counting the number of centroblasts at 40x high-power field (HPF); i.e., grade 1, 0–5 centroblasts/HPF; grade 2, 6–15 centroblasts/HPF; and grade 3, >15 centroblasts/HPF.

• MIB-1 (Ki-67) is a useful marker to differentiate most grade 1 and grade 2 from grade 3.

• In situ follicular neoplasia with a low rate of progression can be detected by flow cytometry studies in half of the cases. Careful interpretation of FNA specimens is recommended.

Fig. 4.29

(a–d) Follicular lymphoma with increased numbers of large atypical lymphoid cells (centroblasts) in grade 1 (a, b), grade 2 (c), and grade 3 (d) follicular lymphoma

Histologic Features

• Effaced nodal architecture in follicular pattern, follicles >75% (Fig. 4.30); in follicular and diffuse pattern, follicles 25–75%; in focally follicular pattern, follicles <25%; and in diffuse pattern, follicles 0%.

  Fig. 4.30

  

  Follicular lymphoma with effaced nodal architecture in a follicular pattern as “balls in a bag”

• Neoplastic follicles are usually round, surrounded by decreased mantle zone and composed of centrocytes and centroblasts without tingible-body macrophages.

• Centrocytes have mature chromatin and folded nuclear membrane; centroblasts show prominent nucleolus and round nuclear contour (Fig. 4.31).

  Fig. 4.31

  

  Neoplastic cells (centrocytes) with folded nuclear contour and mature chromatin; admixed centroblasts (arrow) with smooth nuclear membrane and vesicular chromatin

• Grades 1–2 (low grade) with similar clinical prognosis

  • Grade 1: <5 centroblasts/HPF

  • Grade 2: 6–15 centroblasts/HPF

• Grade 3 (high grade): >15 centroblasts/HPF

  • Grade 3A: centroblasts separated by centrocytes

  • Grade 3B: sheets of centroblasts

Immunohistochemistry and Ancillary Studies

• Flow cytometry: CD19+, CD20 +, CD10 + (Fig. 4.32a–d)

  Fig. 4.32

  

  (a–d) Flow cytometry studies of follicular lymphoma with coexpression of CD10 , high intensity of CD20 , and immunoglobulin light chain restriction

• IHC: CD20 +, CD10 +, BCL2 +, BCL6 + and LIM-only transcription factor-2 (LMO2 )+ (Fig. 4.33)

  Fig. 4.33

  

  Follicular lymphoma with LMO2 positivity

• FISH: positive for t(14;18)(q32;q21) (IGH;BCL2) (Fig. 4.34)

  Fig. 4.34

  

  FISH in follicular lymphoma with t(14;18) ( IGH; BCL2 ) (1R1G2A, arrow)

Differential Diagnosis

• Reactive lymph node

• Other low-grade lymphoma

Marginal Zone Lymphoma (MZL )

Clinical Features

• Involving nodal and extranodal sites

• Commonly in women

• Usually in the elderly

Cytological Features (Fig. 4.35a–f)

• Cellular smear

• A heterogeneous population of cells, including plasmacytoid cells, plasma cells, scattered immunoblasts, centrocyte-like cells

• Monocytoid B cells

Fig. 4.35

(a–f) Marginal zone lymphoma with a heterogeneous population of cells, including plasmacytoid cells, plasma cells, scattered immunoblasts, centrocyte-like cells on Diff-Quik (S), and Pap stain (b). Note that immunostain performed on the direct FNA smears showed CD20 positivity (c), Kappa light chain restriction (d), lack of Lambda light chain (e), and low Ki-67 proliferative index (f)

Histologic Features

• Expanded marginal zone (Fig. 4.36)

  Fig. 4.36

  

  Marginal zone lymphoma with effaced nodal architecture and marked marginal zone expansion

• Neoplastic cells may appear as monocytoid, plasmacytoid, or centrocyte-like cells (Fig. 4.37).

  Fig. 4.37

  

  Neoplastic marginal zone cells show round nuclear contour and mature chromatin with monocytoid or plasmacytoid appearance

Immunohistochemistry and Ancillary Studies

• Flow cytometry: CD19+, CD20 +, CD5 -, CD10 -, CD23 -

• IHC: CD20 +, CD43 + (50% of cases), immunoglobulin superfamily receptor translocation associated 1(IRTA1)+ (Fig. 4.38)

  Fig. 4.38

  

  Neoplastic marginal zone cells positive for IRTA1

Differential Diagnosis

• Reactive lymph node

• Other low-grade lymphoma

Mantle Cell Lymphoma (MCL )

Clinical Features

• 3–10% of non-Hodgkin lymphomas.

• Median age of 60 and male predominance.

• Involvement of the lymph nodes, spleen, and bone marrow.

• Up to 30% with GI involvement.

• Up to 25% with peripheral blood involvement.

• Two types: sex-determining region Y box (SOX)11-positive/immunoglobulin heavy chain variable (IGHV)-unmutated MCL typically involves lymph nodes and other extranodal sites with an aggressive clinical behavior; SOX11 -negative/IGHV-mutated MCL usually involves the peripheral blood, bone marrow, and spleen with an indolent clinical course.

Cytological Features (Fig. 4.39a, b)

• Cellular smear.

• Homogeneous population of small- to intermediate-size lymphocytes

• Slightly cleft nuclear membrane.

• Condensed chromatin.

• Inconspicuous nucleoli.

• Many large cells are seen in a blastoid variant (resembling lymphoblasts) with a high mitotic index (>10/10 HPF).

• Positive for CD20 , CD5 , and negative for CD23 and CD10 .

• FISH showing nearly 100% of cases with the t(11;14) translocation.

• Cyclin D1 overexpression by immunostain.

Fig. 4.39

(a, b) Mantle cell lymphoma with a homogeneous population of small to intermediate-size lymphocytes with slightly cleft nuclear membranes on Diff-Quik (a) and Pap stain (b)

Histologic Features

• Nodular pattern with expanded mantle zone and may show a diffuse pattern (Fig. 4.40).

  Fig. 4.40

  

  Mantle cell lymphoma with effaced nodal architecture and mantle zone expansion in a vaguely nodular pattern

• Neoplastic cells with mature chromatin and irregular nuclear contour (Fig. 4.41).

  Fig. 4.41

  

  Neoplastic mantle cells with irregular nuclear contour and mature chromatin

• Capillary proliferation (Fig. 4.42).

  Fig. 4.42

  

  Mantle cell lymphoma with capillary proliferation

• Aggressive variants:

  • Blastoid variant with lymphoblasts

  • Pleomorphic variant with oval to irregular nuclear contour and prominent nucleolus

• Other variants:

  • Small cell variant mimicking SLL

  • Marginal zone-like variant with monocytoid cells

• In situ mantle cell neoplasia with a low rate of progression and indolent clinical course. Careful interpretation of FNA specimen is recommended.

Immunohistochemistry and Ancillary Studies

• Flow cytometry: CD19+, CD20 +, CD5 +, FMC7+, CD43 - (Fig. 4.43a–d)

  Fig. 4.43

  

  (a–d) Flow cytometry studies of mantle cell lymphoma with coexpression of CD5 , positivity of FMC7, and immunoglobulin light chain restriction

• IHC: CD20 +, CD5 +, BCL1+, SOX11 + (Figs. 4.44 and 4.45)

  Fig. 4.44

  

  Immunohistochemical study of SOX11 in mantle cell lymphoma shows mantle zone expansion

  Fig. 4.45

  

  Immunohistochemical study in mantle cell lymphoma shows mantle cells positive for SOX11

• FISH: t(11;14) (CCND1;IGH) (Fig. 4.46)

  Fig. 4.46

  

  FISH in mantle cell lymphoma with t(14;18) (CCND1;IGH) (1R1G2F)

Differential Diagnosis

• Reactive lymph node

• Other low-grade lymphoma

Plasmacytoma/Multiple Myeloma

Cytological Features (Fig. 4.47a, b)

• Mature or immature plasma cells.

• Binucleation or multinucleation.

• Intranuclear bodies (Dutcher body) or intracytoplasmic bodies (Russell body).

• Positive for CD38 and CD138 and negative for CD20 .

• May be positive for epithelial membrane antigen (EMA ), but negative for cytokeratin.

• IgM MGUS is more closely related to LPL.

Fig. 4.47

(a, b) Plasmacytoma on Diff-Quik (a) and Pap stain (b)

Histologic Features

• Sheets of plasma cells in tissue or lymph node (Figs. 4.48 and 4.49).

  Fig. 4.48

  

  Plasmacytoma with sheets of plasma cells

  Fig. 4.49

  

  Neoplastic plasma cells with less mature chromatin, nucleolus, and scattered binucleation

• Multiple myeloma in bone marrow biopsy: monotypic plasma cells represent >30% of marrow cellularity.

Immunohistochemistry and Ancillary Studies

• IHC: CD138 + (Fig. 4.50) used to evaluate volume of plasma cells and kappa and lambda for clonality; some neoplastic plasma cells show aberrant expression of CD56, BCL1, and CD117 .

  Fig. 4.50

  

  Plasmacytoma with sheets of CD138 positive plasma cells

Large B-Cell Lymphom a (LBCL)

Clinical Features

• Accounts for 30%–40% of adult non-Hodgkin lymphomas in western countries.

• Nodal or extranodal disease.

• Forty percent with initial extranodal presentation, GI tract most common.

• HIV or other immunodeficiency is a risk factor.

• Many morphologic variants, including centroblastic, immunoblastic, and anaplastic, and subtypes, such as T-cell/histiocytes-rich, primary DLBCL of the CNS, primary cutaneous DLBCL leg type and EBV -positive DLBCL, NOS, et al.

• t(14;18) chromosomal translocation in 30% of cases.

• Two major patterns of gene expression in DLBCL : germinal center (GC)-B cell type DLBCL and activated B-cell (ABC)-type DLBCL. GC-type DLBCL has a much better prognosis than ABC-type DLBCL.

Cytological Features (Fig. 4.51a–g)

• Highly cellular specimen.

• Dispersed large uniform to variable-size lymphoid cells.

• Numerous lymphoglandular bodies in the background.

• Large pleomorphic nuclei, irregular nuclear contour, and prominent nucleoli.

• Multinucleated giant cells can be seen.

• Variable nuclear-to-cytoplasmic ratio.

• Cohesive groups of large atypical lymphoid cells may mimic other malignant tumors, such as carcinoma , melanoma, and sarcoma .

• Tumor necrosis and mitosis are usually present.

Fig. 4.51

(a–g) Large B-cell lymphoma with large uniform to variable-size lymphoid cells on Diff-Quik (a, b) and Pap stain (c). Note that LBCL may mimic other malignant tumors, such as carcinoma , as shown in (d), on cellblock preparation (e), positive for CD20 (f) and increased Ki-67 proliferative index (g)

Histologic Features

• Effaced nodal architecture in a diffuse pattern by medium to large neoplastic lymphocytes

• Neoplastic cells in sheets or a scattered pattern, depending on the subtype (Figs. 4.52 and 4.55)

  Fig. 4.52

  

  Diffuse large B-cell lymphoma with effaced nodal architecture in a diffuse pattern by sheets of large cells showing vesicular chromatin and prominent nucleolus

Immunohistochemistry and Ancillary Studies

• IHC: positive for the B-cell markers CD20 (Figs. 4.53 and 4.56), paired box gene (PAX)5 (Fig. 4.54), B-cell Oct binding protein 1 (BOB1), octamer-binding transcription factor 2 (Oct2); MIB evaluates the proliferation rate.

  Fig. 4.53

  

  Diffuse large B-cell lymphoma with sheets of CD20 -positive neoplastic cells

  Fig. 4.54

  

  Diffuse large B-cell lymphoma with sheets of PAX5 -positive neoplastic cells

  Fig. 4.55

  

  Diffuse large B-cell lymphoma with effaced nodal architecture in a diffuse pattern by scattered large cells showing pleomorphism

  Fig. 4.56

  

  The large pleomorphic cells in diffuse large B-cell lymphoma with CD20 positivity

• Subclassification:

  • GCB-type DLBCL : CD10 +, BCL6 +, multiple myeloma 1 (MUM1 )-

  • ABC-type DLBCL : CD10 -, BCL6 -, MUM1 +

• Other types include double-hit or triple-hit HGBCL with rearrangements of MYC and BCL2 and/or BCL6 , and double-expresser HGBCL with immunostain of MYC (>40%) and BCL2 (>50%) but lack MYC and BCL2 chromosomal alteration.

Differential Diagnosis

• Reactive lymph node

• High-grade lymphoma and Hodgkin lymphoma

• Melanoma

• Carcinoma

• Sarcoma

Burkitt Lymphoma (BL)

Clinical Features

• Endemic BL, sporadic BL, and immunodeficiency-related BL.

• Extranodal involvement frequent in the jaw, facial bone, abdominal organs, and breast.

• EBV plays an important role in endemic BL.

• Transcription factor 3 (TCF3) mutation in 40% of endemic BLs and 70% of sporadic BLs and immunodeficiency-related BLs.

Cytological Features (Fig. 4.57)

• Cellular smear.

• Monotonous population of medium-size lymphoid cells.

• Usually smooth nuclear membrane, small notched or indented, may be seen.

• Finely stippled nuclear chromatin.

• Multiple conspicuous nucleoli.

• Moderate amount, deeply basophilic cytoplasm with tiny vacuoles.

• CD20 , CD10 , BCL6 positive.

• All cases positive for the t(8;14) translocation, involving MYC .

Fig. 4.57

Burkitt lymphoma with a monotonous population of medium-size lymphoid cells. Note the deeply basophilic cytoplasm with tiny vacuoles

Histologic Features

• Effaced nodal architecture with a “starry sky” pattern and composed of sheets of neoplastic lymphocytes and scattered tingible-body histiocytes (Fig. 4.58)

  Fig. 4.58

  

  Burkitt lymphoma with sheets of lymphoma cells admixed with histiocytes as a “starry sky” pattern

• Neoplastic lymphocytes are medium in size with a round to slightly irregular nuclear contour and small nucleoli with a “snake head” appearance (Fig. 4.59).

  Fig. 4.59

  

  Burkitt lymphoma cells with round nuclear contour and small nucleoli as a “snake head” appearance

Immunohistochemistry and Ancillary Studies

• IHC: strongly positive for CD20 , CD10 , BCL6 , c-MYC and negative for BCL2 with proliferation rate of 100% by MIB-1 stain (Fig. 4.60)

  Fig. 4.60

  

  Burkitt lymphoma cells with 100% of proliferation rate by Ki67 (MIB) immunohistochemical stain

• FISH: MYC translocation (Fig. 4.61)

  Fig. 4.61

  

  FISH in Burkitt lymphoma with MYC rearrangement (break-apart, 1R1G1F)

• A subset lacking MYC rearrangement called “Burkitt-like lymphoma with 11q aberration” shows the same morphology and similar clinical course.

Differential Diagnosis

• LBCL

• Viral infection with reactive change

• Lymphoblastic lymphoma

T-Cell Lymphoma

Clinical Features

• Relatively uncommon lymphoid neoplasm, accounting for less than 12% of non-Hodgkin lymphomas , including peripheral T-cell lymphoma (PTCL), unspecified T-cell lymphoma, NK-cell lymphoma, ALCL , and nodal T-cell lymphoma with TFH phenotype

• More common in Asia

Cytological Features (Fig. 4.62a, b)

• Polymorphous population of a spectrum of small, medium, and large lymphocytes.

• Convoluted nuclear membranes, vesicular or coarse chromatin, and prominent nucleoli.

• Binucleation and multinucleation can be seen.

• Cytoplasm ranging from scant to abundant, pale to basophilic.

• Histiocytes, eosinophils, plasma cells and neutrophils can be seen.

• Granulomas can be seen.

Fig. 4.62

(a, b) T-cell lymphoma with a polymorphous population of a spectrum of small, medium, and large lymphocytes on Diff-Quik (a) and Pap stain (b)

Histologic Features

• Effaced nodal architecture with perifollicular (T-cell zone) expansion (Fig. 4.63).

  Fig. 4.63

  

  Peripheral T-cell lymphoma with effaced nodal architecture and perifollicular expansion

• Neoplastic lymphocytes are medium in size with irregular nuclear contour, vesicular chromatin, and prominent nucleoli; they form sheets or a scattered pattern (Fig. 4.64).

  Fig. 4.64

  

  Neoplastic T cells are medium in size with vesicular chromatin and nucleolus; there is a background of mature lymphocyte and scattered eosinophils

Immunohistochemistry and Ancillary Studies

• Positive for, but often loss of one or more of, the T-cell markers CD2 , CD3 , CD5 and CD7 with either CD4 or CD8 .

• Angioimmunoblastic T-cell lymphoma (Fig. 4.65) and two new subtypes – follicular center T-cell lymphoma and nodal PTCL with TFH type – show the follicular center markers CD279/programmed death 1 (PD1), CD10 , BCL6 , chemokine (C-X-C motif) ligand 13 (CXCL13), inducible T-cell co-stimulator (ICOS), serum amyloid P (SAP), and chemokine receptor type 5 (CCR5).

  Fig. 4.65

  

  Angioimmunoblastic T-cell lymphoma with effaced nodal architecture and perifollicular expansion by monocytoid lymphocytes and capillary proliferation

Anaplastic Large Cell Lymphoma (ALCL )

Clinical Features

• Three percent of adult non-Hodgkin lymphomas.

• ALK+ ALCL represents 10–20% of childhood lymphomas; ALK- ALCL peaks in adults (40–65 years).

• CD30 -positve T-cell lymphoma.

• 70–80% with t(2;5) translocation and ALK expression.

• ALK-positive cases frequently involve both nodal and extranodal sites and have a better prognosis.

Cytological Features (Fig. 4.66a–d)

• Cellular smear.

• Pleomorphic cells with variable sizes.

• Binucleation or multinucleation or bizarre cells can be seen.

• Large nuclei with indentation and lobulation.

• Variable amount of cytoplasm.

• Heterogeneous population in the background, including small lymphoid cells, histiocytes, and plasma cells.

• CD2 and CD4 are the more sensitive markers.

• More than 75% of cases are negative for CD3 .

• CD30 positive in all cases, usually in large lymphoid cells; most cases are positive for EMA .

• Seventy percent of cases show ALK expression (either nuclear or cytoplasmic staining).

• EBV is negative.

Fig. 4.66

(a–d) Anaplastic large cell lymphoma with pleomorphic cells with variable sizes on Diff-Quik (a, b), cellblock (c), positive for CD30 (d)

Histologic Features

• Effaced nodal architecture with expanded perifollicular areas (Fig. 4.67).

  Fig. 4.67

  

  Anaplastic large cell lymphoma with effaced nodal architecture and perifollicular expansion

• Neoplastic cells are pleomorphic and hallmark cells with horseshoe-like nucleus (Fig. 4.68).

  Fig. 4.68

  

  Neoplastic T cells are pleomorphic and some with horseshoe-like nucleus – hallmark cells

Immunohistochemistry and Ancillary Studies

• Positive for T-cell markers, CD30 (Fig. 4.69), and ALK1 (Fig. 4.70) and negative for CD15

  Fig. 4.69

  

  Neoplastic T cells positive for CD30

  Fig. 4.70

  

  Neoplastic T cells positive for ALK1

• ALK1+ and ALK1- types share a similar molecular Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3 ) pathway.

• New type: ALK-negative ALCL arising in association with breast implants shows similar morphological features, but neoplastic cells are confined to the seroma fluid without invasion of the capsule. Treatment is removal of the implant and capsule.

Differential Diagnosis

• Hodgkin lymphoma

• Other high-grade lymphoma

• Carcinoma

• Melanoma

• Sarcoma

Hodgkin Lymphoma

Clinical Features

• Cervical, mediastinal, or axillary mass

• Bimodal age curve with a peak in young adults (15–35 years) and a second in the elderly

Cytological Features (Fig. 4.71a–h)

• Low to moderate cellularity.

• Polymorphous population of small lymphoid cells, plasma cells, histiocytes, and eosinophils.

• Classic multinucleated Reed-Sternberg cells and mononuclear Hodgkin cells.

• Fibrosis and crushed cellular components are frequently seen.

• Excisional biopsy should be suggested for further classification.

Fig. 4.71

(a–h) Hodgkin lymphoma with classic Reed-Sternberg cells and mononuclear or multinucleated Hodgkin cells in the background of a polymorphous population of small lymphoid cells, plasma cells, histiocytes, and eosinophils (a–e), and small tissue section (f), Hodgkin cells positive for CD15 (g), and CD30 (h)

Histologic Features

• Effaced nodal architecture in a nodular or diffuse pattern with two types: CHL (nodular sclerosis, mixed cellularity, lymphocyte rich, and lymphocyte depleted) (Figs. 4.72a–d and 4.73a–c) and nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) (Figs. 4.74 and 4.75a–d)

  Fig. 4.72

  

  (a–d) Classical Hodgkin lymphoma with nodular sclerosis (a), mixed cellularity (b), lymphocyte rich (c), and lymphocyte depleted (d)

  Fig. 4.73

  

  (a–c) High-power view of classical Hodgkin lymphoma with Reed-Stenberg cells in a background of mixed lymphocytes, plasma cells, and eosinophils in nodular sclerosis and mixed cellularity (a), neoplastic cells with background of lymphocytes in lymphocyte-rich (b) and neoplastic cells with background of hypocellularity in lymphocyte depleted (c)

  Fig. 4.74

  

  Nodular lymphocytic-predominant Hodgkin lymphoma with large nodular pattern

  Fig. 4.75

  

  (a–d) Nodular lymphocytic-predominant Hodgkin lymphoma with scattered lymphocyte-predominant cells in a background of mature lymphocytes

• Large neoplastic cells including Reed-Sternberg cells, Hodgkin cells, lacunar cells, and popcorn cells (Fig. 4.76a–d)

  Fig. 4.76

  

  (a–d) Hodgkin lymphoma with Reed-Sternberg cells (a), Hodgkin cells (b), lacunar cells (c), and popcorn cells (d)

Immunohistochemistry and Ancillary Studies

• Reed-Sternberg cells in CHL are positive for CD15 , CD30 , and K homology domain-containing protein overexpressed in cancer 1 (KOC1) (Fig. 4.77a–c) and negative for CD3 and CD20 .

  Fig. 4.77

  

  (a–c ) Reed-Sternberg cells in classical Hodgkin lymphoma with positive CD15 (a), positive CD30 (b), and positive KOC1 (c)

• NLPHL is a monoclonal B-cell neoplasm that is CD45 positive, CD20 positive, PAX5 positive, CD15 negative, and CD30 negative (Fig. 4.78a–e).

  Fig. 4.78

  

  (a–e) Lymphocyte-predominant cells in nodular lymphocytic-predominant Hodgkin lymphoma with positive CD45 (a), positive CD20 (b), negative CD3 (c), negative CD15 (d), and negative CD30 (e)

• Lymphocyte-rich CHL has features intermediate between CHL and NLPHL .

Differential Diagnosis

• Poorly differentiated carcinoma

• Melanoma

• Sarcoma

• Reactive lymph node with many immunoblasts

Others

Langerhans Cell Histiocytosis (LCH )

Cytological Features (Fig. 4.79a–e)

• Langerhans histiocytes and eosinophils.

• Nuclear grooves or linear folds are seen in Langerhans cells.

• Immunostain shows positivity for both S100 and CD1a .

• Multinucleated giant cells may be present.

• Some of these neoplasms may have transdifferentiation to follicular lymphoma, CLL, B- or T-lymphoblastic neoplasms carrying the same IGHV, or T-cell receptor (TCR) gene rearrangement.

Fig. 4.79

(a–e) Langerhans cell histiocytosis with Langerhans histiocytes and eosinophils in (a) and (b), prominent nuclear grooves or linear folds seen in Langerhans histiocytes (c), on cellblock (d) and positive for CD1a (e)

Histologic Features

• Effaced nodal architecture with expanded sinus and pericortex by large neoplastic Langerhans cells

• In early stage, Langerhans cells prominent admixed with eosinophils and neutrophils; in late stage, the number of Langerhans cells is decreased with fibrosis and increased foamy macrophages.

Myeloid Sarcoma

Cytological Features (Fig. 4.80a–e)

• Myeloid cells in various stages of differentiation

• Can be mainly blasts or a mixed population of myeloid cells in different stages

• Eosinophilic myelocytes may be seen.

Fig. 4.80

(a–e) Myeloid sarcoma on Diff-Quik (a, b), Pap stain (c), positive for CD34 (d) and CD43 (e) on cellblock sections

Histologic Features

• Effaced nodal or tissue architecture with sheets of myeloblasts (Figs. 4.81 and 4.82), rarely, of erythroid precursors or megakaryoblasts

  Fig. 4.81

  

  Myeloid sarcoma with sheets of blasts

  Fig. 4.82

  

  Myeloblasts with fine chromatin, round nuclear contour, and frequent mitotic figures

• May present de novo, with peripheral and bone marrow involvement, relapse of acute myeloid leukemia (AML) or progression of a prior myelodysplastic syndrome (MDS), myeloproliferative neoplasm (MPN), or MDS/MPN. Recommend clinical correlation.

Immunohistochemistry and Ancillary Studies

• Myeloblasts positive for myeloperoxidase (MPO , Fig. 4.83), CD117 , lysozyme (Fig. 4.84), CD68 , CD99, and CD34

  Fig. 4.83

  

  Myeloblasts with positive myeloperoxidase

  Fig. 4.84

  

  Myeloblasts with positive lysozyme

Lymphoblastic Lymphoma

Clinical Features

• A childhood disease

• 90% precursor T-lymphoblastic cells and 10% precursor B lymphoblastic cells.

• A designation of lymphoma is given when a patient presents as a mass lesion and less than 25% blasts in bone marrow.

• T-lymphoblastic lymphoma frequently present with a mediastinal mass.

• Indolent T-lymphoblastic proliferation may mimic T-lymphoblastic lymphoma. It typically involves lymphoid tissue of the upper aerodigestive tract without systemic dissemination and also no clonality detected.

Cytological Features (Fig. 4.85a–c)

• Cellular smear

• Relatively uniform population of medium-size lymphoid cells

• Fine, delicate, and powdery nuclear chromatin

• Small to conspicuous nucleoli

• Nuclear membrane variable from smooth to convoluted

• Scant to small amount of cytoplasm

• Cytoplasmic vacuoles can be seen

Fig. 4.85

(a–c) Lymphoblastic lymphoma with relatively uniform population of medium-size lymphoid cells, with fine, delicate, and powdery nuclear chromatin on Diff-Quik (a, b) and Pap stain (c)

Histologic Features

• Effaced nodal architecture with sheets of blasts (Fig. 4.86) and may have a “starry sky” pattern.

  Fig. 4.86

  

  Lymphoblastic lymphoma with effaced nodal architecture in a diffuse pattern by sheets of neoplastic cells

• Neoplastic cells are medium in size with vesicular chromatin and small nucleolus (Fig. 4.87).

  Fig. 4.87

  

  Neoplastic cells with round nuclear contour, vesicular chromatin, and small nucleoli; in a background of mature lymphocytes and eosinophils

• New type: Early T-precursor (ETP) lymphoblastic leukemia shows blasts positive for CD2 , CD7 , cytoplasmic CD3 , and CD4 and negative for CD1a , CD5 (or weak expression) and CD8 with one or more of the myeloid/stem cell markers CD34 , CD117 , CD13, CD33, CD11b, or CD65 (Figs. 4.88 and 4.89a, b). It has a very poor outcome.

  Fig. 4.88

  

  Flow cytometry studies of lymphoblast positive for cCD3 and CD34 , and low intensity of CD5 and negative for sCD3, CD8 , and MPO (a few blasts expressing MPO in low intensity) with aberrant expression of CD33

  Fig. 4.89

  

  Neoplastic cells positive for cCD3 (a) and negative for CD1a (b)

• New provisional entity: Indolent T-lymphoblastic proliferation belongs to nonneoplastic entity and may mimic T-lymphoblastic lymphoma. IHC: TdT +, no aberrant phenotype, and not clonal. It mostly occurs in lymphoid tissue of upper aerodigestive tract with good prognosis.

Immunohistochemistry and Ancillary Studies

• Terminal deoxynucleotidyl transferase (TdT )-positive in both T and B lymphoblasts.

• T lymphoblasts are positive for CD7 and cytoplasmic CD3 with coexpression of CD4 and CD8 and also positive for other T-cell markers, such as CD1a and CD2 .

• B lymphoblasts are positive for CD19, CD79a , CD10 , and CD34 .

Tumors Mimicking Lymphomas

Melanoma

Cytological Features

• Loosely cohesive groups and single cells

• Binucleation and multinucleation

• Intranuclear inclusions

• Plasmacytoid cells with abundant cytoplasm

• Prominent nucleoli

• Dusty pigments

Small Cell Undifferentiated Carcinoma

Cytological Features

• Cohesive and single neoplastic cells.

• Very high nuclear-to-cytoplasmic ratio.

• Neuroendocrine chromatin.

• Inconspicuous nucleoli.

• Single cell necrosis and many mitosis.

• Blue bodies in the background may resemble lymphoglandular bodies.

Undifferentiated Carcinoma

• Nasopharyngeal carcinoma

• Poorly differentiated squamous cell carcinoma

• Basaloid squamous cell carcinoma

• Merkel cell carcinoma

Small Round Cell Tumors

• Rhabdomyosarcoma

• Ewing’s sarcoma /primitive neuroectodermal tumor (PNET)

• Neuroblastoma

• Desmoplastic small round cell tumor

Seminoma

Cytological Features

• Two populations of cells: large neoplastic tumor cells and small benign lymphoid cells.

• The neoplastic cells are large and relatively uniform in size.

• Single prominent nucleoli.

• Cytoplasmic vacuoles can be seen.

Thymoma

Cytological Features

• Two populations of cells: epithelial cells and lymphoid cells.

• Can be predominately lymphoid cells.

• Lymphoid cells are CD3 -positve and TdT -positive cortical thymocytes.

• Epithelial cells are positive for p63.

Case Presentations

There are three scenarios encountered in practice when evaluating an enlarged lymph node. Case Scenario 1 is how to make a diagnosis and classification of low-grade B-cell lymphoma based on morphology, flow cytometry, and molecular studies; Case Scenario 2 is how to work on a blast-looking lymphoma in a young patient and what immunophenotypic and molecular tests should be ordered; and Case Scenario 3 is how to deal with a T-cell lymphoma in an elderly patient and what immunophenotypic features need to be paid attention to.

Case Scenario 1

Learning Objective

• 1. To reiterate the diagnostic criteria for low-grade B-cell lymphomas on morphological, immunophenotypic, and molecular features (Table 4.4)

  Table 4.4 Summary of most common low-grade B-cell lymphomas

Case

A 67-year-old female presented with a 2 x 1 cm left neck mass located in zone 5. She first noticed it 6 months ago and was not treated. She was otherwise healthy with no significant past medical history, no symptoms, and no weight loss. CT scan revealed a few tiny lymph nodes other than the enlarged lymph node mentioned above. Excisional biopsy was performed. The morphological features are shown in Figs. 4.90 and 4.91. Flow cytometry studies revealed a population of monotypic B cells positive for CD19 and CD20 and negative for CD5 , CD10 , and CD23 (Fig. 4.92a–d).

Fig. 4.90

Lymphoplasmacytic lymphoma with effaced nodal architecture and perifollicular expansion

Fig. 4.91

Neoplastic cells in lymphoplasmacytic lymphoma show round nuclear contour and mature chromatin with plasmacytoid appearance

Fig. 4.92

(a–d) Flow cytometry studies of lymphoplasmacytic lymphoma show lymphoma cells negative for CD5 (a) and CD10 (b) with immunoglobulin light chain restriction (c, d)

At this point, it is a low-grade B-cell lymphoma. Based on immunophenotypes, the differential diagnosis includes MZL , LPL, and other atypical B-cell lymphomas. Typically B-cell SLL coexpresses CD5 and CD23 ; MCL is positive for CD5 and FMC7; and follicular lymphoma is positive for CD10 , but all the B-cell lymphomas can show an atypical immunophenotype with loss of one or more immunophenotypic marker(s). The morphological pattern showed perifollicular expansion by monotonous monocytoid/plasmacytoid cells, favoring LPL. Now the molecular test will be helpful to make the right classification of this low-grade B-cell lymphoma. Molecular testing showed MYD88 mutation (Fig. 4.93).

Fig. 4.93

Molecular study of lymphoplasmacytic lymphoma with MYD88 L265P mutation: a mutation in chromosome 3p22 in a single nucleotide change, T to C (inside frame), in MYD88, resulting a switch of leucine to proline at amino acid position 265 (L265P)

Final Diagnosis

Lymphoplasmacytic lymphoma (LPL).

What Are the Learning Points from This Case?

The learning points from this case include:

• 1. It is important to evaluate the pattern of effaced nodal architecture and cytological features of neoplastic cells, although there is overlapping in different low-grade B-cell lymphomas.

• 2. Every low-grade B-cell lymphoma has its typical immunophenotypic features, but it should be noted that any lymphomas could have atypical immunophenotypic features.

• 3. FISH and molecular tests, including specific translocation or mutation, would be helpful to make an accurate classification when immunophenotypic features are equivocal.

Case Scenario 2

Learning Objectives

• 1. To identify high-grade lymphomas, especially in young patients

• 2. To review the clinical, morphological, immunophenotypic, and molecular features of high-grade hematopoietic tumors (Table 4.5)

  Table 4.5 Summary of most common high-grade hematolymphoid tumors

Case

A previously heathy 14-year-old boy presented with new-onset dysphagia and snoring, followed by a change in his voice. Symptom started around the time when he and his family had upper respiratory infections. He visited his family doctor, who found him with right tonsillar hypertrophy and positive for Streptococcus. The boy was treated with multiple courses of antibiotics with minimal improvement in symptoms. A tonsillectomy was performed. The right tonsil was 4.0 x 3.5 x 1.5 cm and left tonsil 3.2 x 2.0 x 1.2 cm. Morphologically, the left tonsil showed lymphoid follicular hyperplasia; the right tonsil revealed focal effacement by sheets of blasts in a “starry sky” pattern (Fig. 4.58). High-power view showed neoplastic cells with round nuclear contour, small nucleoli, and frequent mitotic figures (Fig. 4.59).

At this point, a diagnosis of high-grade hematolymphoid tumor can be made. Differential diagnosis includes lymphoblastic lymphoma, DLBCL , BL, or myeloid sarcoma . A definite diagnosis cannot be rendered without immunophenotypic study.

Flow cytometry studies showed a population of monotypic B cells with coexpression of CD10 and negative for the blast markers of CD34 and TdT and T-cell or myelomonocytic markers. Immunohistochemical stains revealed the neoplastic cells to be positive for CD20 , BCL6 , and MYC and negative for BCL2 with a proliferation rate of 100% by Ki67 stain (Fig. 4.37). EBV was negative by in situ hybridization. FISH study was positive for MYC (8q24.1) rearrangement (Fig. 4.61).

Final Diagnosis

Burkitt lymphoma (BL)

What Are the Learning Points from This Case?

The learning points from the case include:

• 1. High-grade hematolymphoid tumor can partially involve lymphoid tissue in the early stage.

• 2. Immunophenotypic features by flow cytometry and immunohistochemical studies are useful to classify the tumor.

• 3. FISH or molecular studies are the gold standard to further confirm the diagnosis.

Case Scenario 3

Learning Objectives

• 1. To review the T-cell leukemia/lymphomas

• 2. To pay attention to immunophenotypic features for classification and guided treatment

Case

A 60-year-old male presented with a rapidly progressive left axillary mass. He had night sweats and a 15-pound weight loss over the previous one to two months. His laboratory tests showed WBC of 7.3, hemoglobin of 11.9, and platelets of 248,000. CT scan revealed lymphadenopathy, including a left axillary lymph node of 3.0 x 3.4 cm with necrosis; periportal, retroperitoneal, bilateral iliac chain, and extensive mesenteric adenopathy, up to 2.4 cm; the enlarged spleen was 15 cm. There was no mediastinal or hilar mass. An excisional biopsy from left axillary lymph node was performed and showed an effaced nodal architecture in a diffuse pattern (Fig. 4.86). Neoplastic cells were medium in size with round nuclear contour, vesicular chromatin, and small nucleolus; there was a background of mature lymphocytes and eosinophils (Fig. 4.87).

At this point, a diagnosis of high-grade hematolymphoid tumor can be made. Differential diagnosis includes lymphoblastic lymphoma, myeloid sarcoma , or acute hematolymphoid tumor with bi-phenotypic features. A definite diagnosis cannot be rendered without immunophenotypic study.

Flow cytometry studies showed a population of blasts positive for cytoplasmic CD3 (cCD3 ) and CD34 and low intensity of CD5 and negative for surface CD3, CD8 , and MPO (a few of blasts expressing MPO in low intensity) with aberrant expression of CD33 (Fig. 4.88). Immunohistochemical studies revealed neoplastic cells positive for cCD3 and negative for CD1a (Fig. 4.89a, b). Molecular test showed clonal TCR gene rearrangement.

Final Diagnosis

Early T-cell precursor lymphoma

What Are the Learning Points from This Case?

The learning points from the case include:

• 1. Lymphoblastic leukemia/lymphoma shares the same morphological features in B-cell acute lymphoblastic leukemia (B-ALL) and T-cell acute lymphoblastic leukemia (T-ALL).

• 2. Immunophenotype by flow cytometry and immunohistochemical studies are helpful to make a right diagnosis.

• 3. The aberrant immunophenotypes that would indicate the prognosis and guide the treatment should be carefully evaluated and mentioned.

Abbreviations List

Abbreviation	Full text
ABC	Activated B-cell
ABL	Abelson murine leukemia viral oncogene homolog 1
ALCL	Anaplastic large cell lymphoma
ALK	Anaplastic lymphoma kinase
ALL	Acute lymphoblastic leukemia
AML	Acute myeloid leukemia
B-ALL	B-cell acute lymphoblastic leukemia
BCL	B-cell lymphoma (BCL1, BCL2, BCL6)
BCR	Breakpoint cluster region
BL	Burkitt lymphoma
BM	Bone marrow
BOB1	B-cell Oct binding protein 1
BRAF	v-raf murine sarcoma viral oncogene homolog B1
CARD11	Caspase recruitment domain-containing protein 11
cCD3	Cytoplasmic CD3
CCND1	Cyclin D1
CCR5	Chemokine receptor type 5
CD	Cluster of differentiation
CHL	Classical Hodgkin lymphoma
CLL	Chronic lymphocytic leukemia
CNS	Central nervous system
CT	Computed tomography
CXCL13	Chemokine (C-X-C motif) ligand 13
DLBCL	Diffuse large B-cell lymphoma
EBV	Epstein-Barr virus
EMA	Epithelial membrane antigen
ETP	Early T precursor
ETV6	ETS variant 6
EZH2	Enhancer of zeste homolog 2
FISH	Fluorescence in situ hybridization
FL	Follicular lymphoma
FMC7	A monoclonal antibody and an epitope of CD20
FNA	Fine needle aspiration
GC	Germinal center
GI	Gastrointestinal
GNA13	Guanine nucleotide-binding protein subunit alpha-13
HGBCL	High-grade B-cell lymphoma
HHV8	Human herpes virus 8
HPF	High-power field
iAMP2	Intrachromosomal amplification of chromosome 21
ICOS	Inducible T-Cell co-stimulator
IgG/A	Immunoglobulin G/A
IGH	Immunoglobulin heavy chain
IGHV	Immunoglobulin heavy-chain variable
IgM	Immunoglobulin M
IHC	Immunohistochemistry
IL3	Interleukin 3
IRF4	Interferon regulatory factor 4
IRTA1	Immunoglobulin superfamily receptor translocation associated 1
JAK/STAT3	Janus kinase/signal transducer and activator of transcription
KMT2A	Lysine methyltransferase 2A
KOC1	K homology domain-containing protein overexpressed in cancer
L256P	Leucine to proline mutation at amino acid position 256
LBCL	Large B-cell lymphoma
LCH	Langerhans cell histiocytosis
LEF1	Lymphoid enhancer-binding factor 1
LMO2	LIM-only transcription factor-2
LN	Lymph node
LPL	Lymphoplasmacytic lymphoma
MALT	Mucosa-associated lymphoid tissue
MCL	Mantle cell lymphoma
MDS	Myelodysplastic syndrome
MGUS	Monoclonal gammopathy of undetermined significance
MIB-1	Mindbomb homolog 1
MLL	Mixed-lineage leukemia
MPN	Myeloproliferative neoplasm
MPO	Myeloperoxidase
MUM1	Multiple myeloma 1
MYC/c-MYC	A regulator gene that codes for a transcription factor
MYD88	Myeloid differentiation primary response gene 88
MZL	Marginal zone lymphoma
N/C	Nuclear to cytoplasmic
NK	Natural killer
NOS	Not otherwise specified
NPM	Nucleophosmin
Oct2	Octamer-binding transcription factors
Pap	Papanicolaou
PAX	Paired box gene
PB	Peripheral blood
PBX1	Pre-B-cell leukemia homeobox 1
PD1	Programmed death 1
PNET	Primitive neuroectodermal tumor
PTCL	Peripheral T-cell lymphoma
PTLD	Posttransplant lymphoproliferative disorders
RUNX1	Rnt-related transcription factor 1
SAP	Serum amyloid P
sCD3	Surface CD3
SLL	Small lymphocytic lymphoma
SOX	Sex-determining region Y box
STAT3	Signal transducer and activator of transcription 3
T-ALL	T-cell acute lymphoblastic leukemia
TCF3	Transcription factor 3
TCR	T-cell receptor
TdT	Terminal deoxynucleotidyl transferase
TFH	T follicular helper
TIA	T-cell intracellular antibody
TNFAIP3	Tumor necrosis factor, alpha-induced protein 3
US, USA	United States (not spelled out in chapter)
WHO	World Health Organization
ZAP-70	Zeta-chain-associated protein kinase 70