Lymphomas

Table Of Contents
  1. Overview
  2. Hodgkin Lymphoma (HL)
  3. Non-Hodgkin Lymphoma (NHL)
  4. WHO Classification of Lymphoma

Overview

Lymphomas are tumors arising from lymphoid cells. They have a much less dramatic presentation than leukemias. They are classified into 2 major groups – Hodgkin’s and Non-Hodgkin’s – based on morphology and immunophenotype. 2/3 of lymphoma present with Lymphadenopathy. The rest can present with extranodal involvement. The best initial diagnostic step for lymphomas is an excisional biopsy. There is no role for Fine needle aspirate cytology since the cancerous cells appear normal. The mainstay of treatment of lymphoma is chemotherapy or immunotherapy.

Hodgkin lymphoma: characterized by Reed Stenberg cells on biopsy. Has mediastinal involvement.

Non-Hodgkin lymphoma: Every other lymphoma that does not fit the characteristics of Hodgkin lymphoma

Aggressive Non-Hodgkin lymphomas: Diffuse Large B-cell Lymphoma, Burkitt’s Lymphoma, and Plasmablastic lymphoma. Have a high incidence in HIV/AIDS patients and are AIDS-defining malignancies.

Ann-Arbor Staging of Lymphoma

***Modifiers: Nodal (N), Extranodal (E), B-symptoms absent/Asymptomatic(A), B symptoms present (B), Bulky disease (X)

StageSites involved
IOne Lymph node site
IITwo or more lymph node sites on one side of the diaphragm
IIITwo or more lymph node sites on both sides of the diaphragm
IVExtranodal sites (lungs, liver, bone marrow etc.) with or without lymph node involvement
Ann-arbor staging
Ann-arbor staging
  • General features of lymphomas
    • Present with Lymphadenopathy
    • Arise within lymph nodes or organized lymphatic tissue (Peyer’s patches, conjunctiva, parapharynx, waldeyer ring, Thymus)
    • Multicentric at presentation and diagnosis IE. they originate in several sites, hence the mainstay for treatment is chemo/immunotherapy
    • Hodgkin lymphoma starts at a localized region (a “pure lymphoma”)
    • Cells can invade the Bone marrow and Peripheral blood establishing a leukemic phase – this is why lymphomas are referred to as a “disease spectrum”. An example is SLL/CLL.
  • Sites of origin of lymphomas
    • Lymph nodes
    • Spleen
    • Thymus
    • Liver
    • Bone Marrow
    • Mucosa Associated Lymphatic Tissue
    • Skin
  • Extranodal sites that may be affected by lymphoma
    • Brain
    • Skin
    • Gastrointestinal and Respiratory Tract
    • Salivary gland
    • Eye
    • Testes
    • Ovary
    • Cervix
  • Causes of Lymphoma
    • EBV virus is associated with Burkitt’s lymphoma First described in Uganda by Sir-Burkitt, a surgeon at Mulago hospital. Sir Epstein later described the virus, which is associated with jaw tumors and 30-40% of the viral genome is found in tumors, and EBV LMP-2 is detected in 90% of Burkitt’s lymphomas
    • Diffuse Large B-cell Lymphoma (DLBL) is associated with immunodeficiency states such as in HIV, tat protein plays a role
    • EBV is also associated with Hodgkin’s lymphoma, DLBL, NK cell lymphomas With demonstratable LMP1
    • Malaria and EBV boost endemic Burkitt’s lymphoma incidence by 100-150 times
    • Plant phorbol esters (Euphobia terucalis) induces t(8;14) in 1% of lymphoblastoid cell lines (BL)
  • Differential diagnoses of lymphoid masses
    • Lymphoma
    • Metastasis
    • Reactive node (Tuberculosis, Acute HIV syndrome): painful lymphadenopathy
    • Sarcoidosis

Hodgkin Lymphoma (HL)

The malignant cells in Hodgkin lymphoma are Reed-Stenberg (RS) cells. They are of B-cell origin. HL presents as painless lymphadenopathy and has a contiguous pattern of spread. The prognosis of HL decreases as reed stenberg cells increase and lymphocytes are depleted. Hodgkin lymphoma classicaly presents with painless lymphadenopathy and B-symptoms (fever, night-sweats, and unintended weight loss). HL has good 5-year survival rates, especially when it presents at a younger age.

Hodgkin lymphoma has a bimodal peak at 30 years and 70 years. Nodular sclerosing type commonly affects young adults while mixed-cellularity affects elderly adults.

Classical Hodgkin Lymphoma

Lymphocyte richComposed of reactive lymphocytes mostly, Mononuclear type RS cells predominate
Mixed cellularityComposed of many different cell types, Classical Owl’s eye RS cells predominate
Nodular sclerosisBands of fibrosis, Lacunar RS cells present
Lymphocyte depletedComposed of many RS cells and its variants

Non-classical Hodgkin Lymphoma

Nodular lymphocyte-predominantComposed mostly of B-cells with few RS cells and variants, predominantly popcorn cells or Lymphohistiocytic variant (behaves like low grade B-cell NHL with CD20+, can advance to DLBCL – Richter’s syndrome)
Hodgkin Lymphoma unclassifiable with DLBCL featuresCharacterized by a syncytium of Reed-Sternberg cells (mononuclear variant) that are CD20+
StageSites involved5-year survival
IOne Lymph node site90%
IITwo or more lymph node sites on one side of the diaphragm90%
IIITwo or more lymph node sites on both sides of the diaphragm80%
IVExtranodal sites (lungs, liver, bone marrow etc.) with or without lymph node involvement70%
  • Risk factors for Hodgkin Lymphoma
    • History of EBV infection (strong association – 3x relative risk with relatives, 100x relative risk with monozygotic twins!)
    • Immunodeficiency (Transplant, HIV, Immunosuppressants and Chemotherapy)
    • Autoimmune disease (Rheumatoid Arthritis, Sarcoidosis)
  • Signs and symptoms
    • Lymphadenopathy
    • Chest pain, dry cough and breathlessness for mediastinal lymphadenopathy
    • Hepatosplenomegaly
    • B-symptoms: night sweats, unintentional weight loss >10%, and Fever > 38 C
    • Pel-Ebstein fevers: specific for HL. These are cyclical fevers that rise and fall every 1 or 2 weeks
    • Alcohol-induced pain/lymphadenitis (highly specific for HL)
    • Generalized or localized pruritus
  • Investigations
    • Complete Blood Count: Elevated or decreased WBC count, Anemia, Eosinophilia
    • Serum chemistry: Increased LDH, Hypercalcemia (paraneoplastic production of Calcitriol),
    • ESR: may be raised
    • Excisional Biopsy and Histology
      • Reed-stenberg cells
      • Polynuclear fused Hodgkin cells
      • Hodgkin cells (mononuclear malignant B-cell)
      • Inflammatory background (lymphocytes, neutrophils, eosinophils, macrophages)
      • Granuloma formation
    • Immunohistochemistry
      • Reed-stenber cells cells**:** CD15+, CD30+ (CD20+, CD45+ and CD79a+ in Nodular lymphocyte predominant HL)
    • HIV antigen-antibody test
    • Chest X-ray for mediastinal mass
    • Whole body PET scan and Bone Marrow biopsy for staging
  • Treatment
    • Consult Haematology/oncology, general surgery, radiation oncology etc.
    • Radiation therapy +/- Low-dose chemotherapy (ABVD) for Stage I and II
    • Chemotherapy (ABVD) for stage III and IV or B-symptoms present
      • Adriamycin → causes dilated cardiomyopathy
      • Bleomycin → causes pulmonary fibrosi
      • Vincristine → causes peripheral neuropathy
      • Dacarbazine → causes myelosupression
    • Counselling and reassurance
  • Factors for poor prognosis
    • Advanced age
    • High stage lymphoma
    • Elevated ESR
    • B-symptoms present
  • What factors should be considered when describing the morphology and type of HL?
    • Pattern of cells present (Mature small lymphocytes, a few plasma cells occasional eosinophils)
    • Predominant Reed-stenberg cell variant present (Classical RE cell, Lacunar cell, Mononuclear variant, Lymphohistiocytic or popcorn cell)
    • Degree of fibrosis

Reed Stenberg Cell Variants

  • Classical Reed-stenberg cell: Predominant in mixed cellularity HL, lymphocyte rich) – classical Owl’s eye appearance of bilobed nuclei and mirrored nucleoli
Classic Reed Stenberg Cell
Classic Reed Stenberg Cell
  • Mononuclear variant: Predominant in mixed and lymphocyte rich HL)
Mononuclear variant
Mononuclear variant
  • Lacunar cell: Predominant in nodular sclerosis subtype HL), folded multilobed nucleus within an open-space (lacuna) which is an artefact of processing
Lacunar cell
Lacunar cell
  • Lymphohistiocytic variants or Popcorn cells: Predominant in nodular lymphocyte-predominant HL,CD20+, CD79a+ and CD45+, BCL-6), infolded nuclear membrane, small nucleoli, fine chromatin and abundant pale cytoplasm
Lymphohistiocytic variant
Lymphohistiocytic variant
  • Anaplastic (pleomorphic) – lymphocyte depleted
  • Mummified – indicates HL but non-specific

Non-Hodgkin Lymphoma (NHL)

Non-Hodgkin lymphomas are other lymphomas that do not fit the criteria for Hodgkin lymphoma. Patients present with painless lymphadenopathy and an abdominal or testicular mass. B-symptoms may not be present. Compared to Hodgkin lymphoma, they tend to present at an advanced stage. Excisional biopsy is the best diagnostic step. The treatment for NHL is chemotherapy at all stages

Median age of diagnosis is 67 years.

Notable Non-Hodgkin lymphomas

Burkitt lymphomat(8;12)c-MYC activation
Mantle Cell lymphomat(11;14)Cyclin-D1 overexpressionCD5+, C20+
Follicular lymphomat(14;18)bcl-2 overexpressionCD10+, CD19+, CD20+
Marginal zone lymphomat(11;18)
  • Non-Hodgkin lymphomas
    • Small Lymphocytic Lymphoma (SLL/CLL)
    • Follicular lymphoma (predominantly small cell)
    • Diffuse Large B-cell lymphoma (DLBCL)
    • Burkitt Lymphoma (BL)
    • High-grade B-cell Lymphoma (Small non-cleaved) Burkitt-like lymphoma
    • Precursor T or B-cell lymphoblastic Lymphoma or Leukemia (Lymphoblastic lymphoma)
    • Mantle cell lymphoma
    • Marginal zone lymphoma
  • Risk factors for Non-Hodgkin lymphoma
    • Older age (67 years)
    • Male sex (1.5:1 M:F)
    • Autoimmune disease (SLE, Sjorgen, celiac disease)
    • Ebstein Barr virus
    • HIV/AIDs (especially CNS lymphomas)
    • Exposure to pesticides, herbicides, Benzene and hair-dye
    • History of chemotherapy and radiation
    • Genetic disorders e.g. Down syndrome, Klinefelter syndrome, Hereditary immunodeficiency
  • Investigations
    • Excisional biopsy
    • Whole body PET scan and Bone marrow biopsy for staging
    • Hepatitis serology before chemotherpay induction
  • Treatment
    • Consult Hematology/oncology, radiation oncology
    • Chemotherapy with R-CHOP
      • Rituximab → sudden death, tumor lysis syndrome (test for HepB before starting, for CD20+ malignant cells)
      • Cyclophosphamide → hemorrhagic cystitis
      • Daunorubicin → Dilated cardiomyopathy
      • Oncovin → peripheral neuropathy
      • Prednisone → cushing syndrome
    • Methotrexate if there is CNS involvement
    • Allopurinol and vigorous hydration ofr tumor lysisi syndrome
    • Counselling and reassurance

Precursor Lymphoma

Precursor neoplasms account for 15% of ALL cases and 90% of Lymphoma cases in children. Pre-T cell and Pre-B cell lymphoma are indistinguishable. They are very aggressive and can progress to ALL. The prognosis is poor due to the presence of genetic translocations and late presentation in adolescents.

Pre-T cell Lymphoma: common in adolescent boys. Has thymic involvement. Highly associated with NOTCH1 mutations

Pre-B cell Lymphoma: manifests as Lymphoma

  • Signs and symptoms
    • Generalized lymphadenopathy
    • Hepatosplenomegaly
    • Bone pain
    • CNS involvement (mimics meningitis)
  • Investigations
    • Immunohistochemistry
      • B-cells: CD19+, CD20+, CD10+ (CALLA)
      • T-cells: CD3+, CD8+
      • B and T-cell: TdT+
    • Molecular studies
      • Translocations: MLL (Mixed Lineage Leukemia) gene, Philadelphia chromosome t(9;22)
  • Morphology of precursor lymphoma
    • Gross: Diffuse lymphoid involvement
    • Microscopy: Effaced (diffuse) follicular pattern, Intermediate sized lymphocytes (lymphoblasts) in a diffuse pattern, with scanty cytoplasm, convoluted nuclear membrane, high-mitotic rate and starry sky appearance (as in Burkitt’s)

Small Lymphocytic Lymphoma (SLL)

SLL is the best example of a peripheral B-cell neoplasm. It has good prognosis nad is mostly an adult disease. It accounts for 5% of Non-Hodgkin Lymphoma. SLL may present with lymphocytosis (leukemia – hence CLL/SLL). 10% of CLL/SLL undergo Richter’s transformation into Diffuse large B-cell Lymphoma.

SLL affects ages > 50 years. It is an indolent disease with a median survival of 5-6 years.

  • Signs and symptoms
    • Generalized lymphadenopathy
    • Hepatosplenomegaly
    • Pallor, Fatigue, Breathlessness (due to cold-agglutinin autoimmune hemolysis)
    • Recurrent and/or severe infections (due to hypogammaglobulinemia)
    • Easy bruising and bleeding (due to autoimmune thrombocytopenia)
  • Investigations
    • Immunohistochemistry
      • B-cell: CD19+, CD20+, CD5+ (show T-cell marker), SIgM or SIgD
      • Genetics: Trisomy 12, del (13q), del (11q) = poor prognostic marker
      • Expresses: Bcl-2 and Bcl-6
  • Morphology of SLL
    • Gross Morphology: Effaced follicular pattern, diffuse infiltrate, Lymphocytes are small (mature appearing, 6-12um), form smudge cells in smears, loose aggregates showing several mitoses (proliferation centers)
Small Lymphocytic Lymphoma
Small Lymphocytic Lymphoma

Follicular Lymphoma

Follicular lymphoma is the most common peripheral Non-hodgkin lymphoma. It affects middle aged men and women equally. It has an indolent course with prolonged survival (7-9 years). 30-50% undergo Richter’s transformation into Diffuse Large B-cell Lymphoma.

  • Signs and symptoms
    • Lymphadenopaty
  • Investigations
    • Immunohistochemistry
      • B-cell: CD19+, CD20+, CD10+ (CALLA), CD5- negative,
      • Translocation: t(14;18) – Bcl-2 to IgH chain
      • Express: Bcl-2 (distinguishes from reactive nodes)
  • Morphology of follicular lymphoma
    • Gross morphology: Effaced follicular pattern with monotonous crowded follicles, lymphocytes are monomorphous small cells with cleaved nuclei (hence small-cleaved cell type), Large cells present with open chromatin, several nucleoli and moderate amount of cytoplasm
Follicular lymphoma
Follicular lymphoma

Diffuse Large B-cell Lymphoma (DLBCL)

DLBCL is an aggressive lymphoma. Although localized, it presents as aggressive extranodal masses. It accounts for 20-30% of non-hodgkin lymphoma in adults, and 5% in children. DLBCL is associated with HIV infection.

The median age of onset is 60 years.

  • Sites commonly involved
    • Peritoneum
    • Pleura
    • Skin
    • Bone
    • Brain
  • Types of DLBCL
    • Immunodeficiency-associated DLBCL (EBV-associated)
    • Body-cavity large cell lymphoma/Primary Effusion Lymphoma (HHV-8 associated in HIV/AIDS)
  • Investigations
    • Immunohistochemistry
      • B-cell: CD19+, CD20+, CD79a+, TdT- negative
      • Translocation: t(14;18) – Bcl-2 to IgH chain
      • Express: Bcl-2, Bcl-6 (point mutation, linked to EBV infection)
  • Morphology
    • Gross morphology: Effaced follicular pattern, Diffuse infiltrate of Lymphocytes that have large lobulated nuclear membranes, multiple nucleoli (may be confused for RE cells), abundant cytoplasms, many mitoses (Most being B-cells, though 20% have T-cell phenotype)
Diffuse Large B-cell lymphoma
Diffuse Large B-cell lymphoma
Diffuse Large B-cell Lymphoma 2
Diffuse Large B-cell Lymphoma 2

Burkitt Lymphoma (BL)

Burkitt Lymphoma was first described in 1958 at Mulago hospital in Uganda. Burkitt cells have a very high turnover rate (more than 90% Ki67 proliferative index! With a 24-hour cell turnover rate).

  • Classes of Burkitt Lymphoma
    • African or endemic type (Mandible, Kidneys, Ovaries, Adrenal medulla)
    • Sporadic or non-endemic type (Abdomen, Caecum, Peritoneum)
    • Immunodeficiency BL (HIV-related, Post-transplant)
  • What is the relationship between MYC and BL?
    • C-myc is located on 8q24 and is part of the Myc family of genes that serve as transcriptional regulators.
    • Myc binds to MAX (heterodimeric partner) forming the MYC-MAX complex that is a potent activator of transcription.
    • Genes targeted by MYC include mediators of metabolism, biosynthesis, and cell-cycle progression.
    • Translocation of Myc genes near immunoglobulin enhancers increases c-myc expression leading to increased cellular proliferation (thus the high doubling rate seen in BL)
  • What is the relationship between EBV, Malaria and BL?
    • EBV causes DNA damage, dysfunctional telomeres and genetic instability through the EBNA1 proteins, LMP1 e.t.c.
    • Malaria causes genomic instability in Endemic BL and can lead to the reactivation of latent EBV and MYC translocations (through activation of TLR-9).
    • Malaria also promotes B-cell proliferation by altering regular immune responses.
  • Investigations
    • Immunohistochemistry
      • B-cell: CD10+, CD19+, CD10+ (CALLA), CD79a+ positive, TdT- negative, SIgM positive, Kappa and Lambda positive
      • Translocation: t(8;14) c-myc on IgH, t(2;8) c-myc of IgL Kappa, t(8;22) c-myc on IgL Lambda
  • Morphology of Burkitt Lymphoma
    • Gross morphology: Effaced follicular pattern, Starry sky appearance (Tingible body macrophages – phagocytosed apoptotic lymphocyte), lymphocytes are intermediate sized (10-25um), have round nuclei, coarse chromatin, prominent nucleoli and royal-blue cytoplasm with vacuoles (demonstratable using Romanowsky-type stains on air-dried samples, vacuoles are thought to be fat globules)
Burkitt Lymphoma - cytoplasmic vacuoles
Burkitt Lymphoma – cytoplasmic vacuoles
Starry sky appearance
Starry sky appearance

Plasma cell lymphoma

Plasma cell lymphomas can be morphologically classified into solitary, multiple myeloma, or plasmablastic lymphomas. They commonly present as lytic bone lesions of the skull, ribs, pelvis and spine

  • Classification of plasma cell lymphomas
    • HIV-related plasmablastic lymphoma of the head
    • Multiple Myeloma
    • Solitary Myeloma
    • Waldenstrom macroglobulinemia (hyperviscosity associated with CLL/SSL)
    • Heavy chain disease (SLL mass in small bowel)
    • Primary immunocyte-associated amyloid (AL amyloidosis)
    • Monoclonal Gammopathy of Undetermined Significance (MGUS)
  • Signs and Symptoms
    • Bone
  • Investigations
    • Immunohistochemistry
      • Plasma cells: CD38+, CD138+, CD20-, MUM1 positive, CD79a_,
    • Serum Protein Electrophoresis
      • Monoclonal Ig peak (M-spike)
    • Urine Protein Electrophoresis
      • Bence jones proteinuria – monoclonal IgL kappa or lambda chains found in urine due to kidney failure
  • What are the causes of kidney failure in plasma cell lymphoma?
    • Hypercalcemia
    • Dehydration
    • Amyloid deposition
  • Morphology of plasma cell lymphoma
    • Abnormal Plasma cells (more than 30% at one site), Mott cells (Morulae cells, grape-like cytoplasmic inclusions of crystallized Ig), Russel bodies (Hyaline intracytoplasmic intranuclear inclusions), Fibrils and Rods, Dutcher bodies (pale staining intranuclear inclusions, single and unusually large, more common in IgA myeloma), Flame cells (Vermillion staining, glycogen rich IgA cytoplasmic projection), Gaucher-like cells (Thesaurocytes, overstuffed fibrils), Cytoplasmic crystals (Occasional in myeloma, common in adult Fanconi syndrome)
Plasma cell lymphoma
Plasma cell lymphoma

WHO Classification of Lymphoma

Evolution of the classification of Lymphoma

  • Timeline: Keil classification → Rappaport classification → Working formulation – Expert hematopathologist (1982, High-grade, Low-grade etc.) → Luke and Collins → WHO → Revised European American classification of Lymphoid neoplasm (1994 REAL) → REAL/WHO 2004
  • Working formulation (1982): divided the neoplasms into Low grade, Intermediate grade and High grade. This was based on cell size and infiltrative nature shown – either diffuse or nodular. Simple but not reproducible. In addition, the system does not classify based on cell line (T or B-cell) and the prognosis and chemotherapy wasn’t based on the specific cell line
  • REAL/WHO(2008): classifies into distinct clinical pathological entities based on morphology, immunophenotype and genetics
    • B-cell lymphomas (85%): Precursor B neoplasms (immature), Peripheral B-cell neoplasm
    • T-cell lymphomas : Precursor T-cell neoplasm, Mature T-cell neoplasm
    • Plasmablastic lymphomas
    • NK-Cell lymphomas: Non B/T-cell lymphoma

WHO-REAL (2008) classification of lymphomas

  • Mature B-cell neoplasms
    • B-cell CLL/SLL
    • B-cell prolymphocytic leukemia
    • Lymphoplasmacytic lymphoma (including Waldenstrom macroglobulinemia)
    • Splenic marginal zone lymphoma
    • Hairy cell leukemia
    • Plasma cell neoplasms
      • Multiple myeloma
      • Plasmacytoma
      • Monoclonal immunoglobulin deposition disease
      • Heavy chain disease
    • Extranodal marginal zone B-cell lymphoma (MALT lymphoma)
    • Nodal marginal zone B-cell Lymphoma
    • Follicular lymphoma
    • Primary cutaneous follicle center lymphoma
    • Mantle cell lymphoma
    • Diffuse Large B-cell lymphoma (NOS)
    • Diffuse Large B-cell lymphoma associated with chronic inflammation
    • EBV positive diffuse large B-cell lymphoma (NOS)
    • Lymphomatoid granulomatosis
    • Primary mediastinal (thymic) large B-cell lymphoma
    • Intravascular large B-cell lymphoma
    • ALK+ large B-cell lymphoma
    • Plasmablastic lymphoma
    • Primary effusion lymphoma
    • Large B-cell lymphoma arising in HHV8-associated multicentric Castleman’s disease
    • Burkitt lymphoma or Leukemia
  • Mature T-cell and NK-cell neoplasm
    • T-cell prolymphocytic leukemia
    • T-cell large granular lymphocyte leukemia
    • Aggressive NK cell leukemia
    • Adult T-cel leukemia or lymphoma
    • Extranodal NK/ T-cell lymphoma (nasal type)
    • Enteropathy associated T-cel lymphoma
    • Hepatosplenic T-cell lymphoma
    • Blastic NK cell lymphoma
    • Mycosis fungoides (Sezary syndrome)
    • Primary cutaneous CD30 positive T-cell lymphoproliferative disorders
    • Peripheral T-cell lymphoma (NO)
    • Angioimmunoblastic T-cell lymphoma
    • Anaplastic large cell lymphoma (ALK-positive and ALK-negative types)
    • Breast plant-associated anaplastic large cell lymphoma
  • Precursor lymphoid neoplasms
    • B-lymphoblastic leukemia or lymphoma (NOS)
    • B-lymphoblastic leukemia or lymphoma with recurrent genetic abnormalities
    • T-lymphoblastic leukemia or lymphoma
  • Hodgkin lymphoma
    • Classical Hodgkin lymphoma
      • Lymphocyte-rich
      • Mixed cellularity Hodkin lymphoma
      • Nodular sclerosis form of Hodkin lymphoma
      • Lymphocyte depleted or not depleted
    • Nodular lymphocyte-predominant Hodkin lymphoma
  • Immunodeficiency-associated lymphoproliferative disorders
    • Associated with a primary immune disorder
    • Associated with HIV
    • Post-transplant
    • Associated with MTX therapy
    • Primary CNS lymphoma