Classification of Hematologic Malignancies Patricia Aoun MD MPH
Objectives Know the basic principles of the current classification system for hematopoietic and lymphoid malignancies Understand the differences and similarities between leukemias and lymphomas Understand the use of specially ancillary techniques in the diagnosis and classification of malignancies
Some definitions: Leukemia Leukos (Gr.), white + haima (Gr.), blood Progressive proliferation of abnormal leukocytes in the blood and bone marrow Classified by- The dominant cell type Myeloid Lymphoid Duration from onset to death if untreated: Acute: few months Chronic: usually greater than 1 year
Some definitions: Lymphoma Lympha (La.), clear spring water + oma (Gr.), tumor Lymphoid proliferations presenting as discrete tumor masses
The distinction between leukemia and lymphoma is artificial Lymphomas can have leukemic phases Chronic lymphocytic leukemia/ Small lymphocytic lymphoma Acute lymphoblastic leukemia/ Lymphoblastic lymphoma Burkitt lymphoma/ Burkitt leukemia Myeloid leukemias can form tumor masses in tissues other than blood or bone marrow Granulocytic sarcoma, chloroma, extramedullary myeloid tumors
Important basic concept OLD CONCEPT: The terms leukemia and lymphoma are descriptive terms that refer to distinct disease entities CURRENT CONCEPT: The terms leukemia and lymphoma are descriptive terms that refer primarily to the tissue distribution of the disease at the time of clinical presentation
Small lymphocytic lymphoma Chronic lymphocytic leukemia Same disease, different presentations
Etiology and pathogenesis Chromosomal translocations Inherited genetic factors Infectious organisms: viruses and bacteria Environmental agents Radiation and chemotherapy
World Health Organization (WHO) Classification of Tumours of Hematopoietic and Lymphoid Tissues Emphasis is on defining disease entities Define disease entity using: Morphology Immunophenotype Genetic abnormalities Clinical features
WHO classification of hematological malignancies: Basic principles FIRST Divide neoplasms according to cell lineage Myeloid Lymphoid Histiocytic/dendritic Mast cell THEN Within each lineage define disease entity using: Stage of cell differentiation Morphology Immunophenotype Cytogenetics Clinical syndrome
WHO Classification: Myeloid neoplasms CHRONIC Chronic myeloproliferative disorders Myelodysplastic syndromes Myelodysplastic/ myeloproliferative diseases ACUTE Acute myeloid leukemia
Chronic myeloproliferative disorders Chronic myelogenous leukemia Polycythemia vera Chronic idiopathic myelofibrosis Essential thrombocythemia Chronic eosinophilic leukemia/hypereosinophilic syndrome Unclassifiable
Myelodysplastic syndromes Refractory anemia (RA) Refractory anemia with ringed sideroblasts (RARS) Refractory cytopenia with multi-lineage dysplasia (RCMLD) Refractory anemia with excess blasts (RAEB) MDS associated with isolated deletion 5q syndrome (5q- syndrome) Unclassifiable
Myelodysplastic/ myeloproliferative diseases Chronic myelomonocytic leukemia Atypical chronic myelogenous leukemia Juvenile myelomonocytic leukemia Unclassifiable
Acute myelogenous leukemia With recurrent cytogenetic abnormalities t(8;21)(q22;q22) inv (16)(p13q22) or t(16;16)((p13;q22) t(15;17)(q22;q12) 11q23 (MLL) abnormalities With multi-lineage dysplasia Therapy-related Alkylating agents, radiation Not otherwise categorized
Acute myelogenous leukemia, not otherwise specified Minimally differentiated (M0) Without maturation (M1) With maturation (M2) Myelomonocytic (M4) Monoblastic/monocytic (M5a, M5b) Erythroid (M6) Megakaryoblastic (M7) Basophilic
WHO classification: Basic principles FIRST Divide neoplasms according to lineage Myeloid Lymphoid Histiocytic/dendritic Mast cell THEN Within each lineage define disease entity using: Stage of cell differentiation Morphology Immunophenotype Cytogenetics Clinical syndromes
WHO classification: Lymphoid neoplasms B-cell T-cell NK-cell Hodgkin cell
WHO classification: Then the stage of differentiation for B-cell and T-cell B-cell Precursor Precursor B-cell acute lymphoblastic leukemia/lymphoma Mature Mature B-cell lymphomas/leukemia Plasma cell disorders T-cell Precursor Precursor T-cell acute lymphoblastic leukemia/lymphoma Mature NK-cell Mature T-cell lymphoma/ leukemia Mature
WHO: Stage of differentiation
WHO classification: Then add morphologic, molecular, cytogenetic and clinical features to further subclassify B-cell CLL/SLL Follicular Diffuse large cell Extranodal marginal zone Burkitt Plasma cell myeloma Many more Hodgkin lymphoma (disease) Classical Hodgkin lymphoma (disease) Lymphocyte predominant Hodgkin lymphoma (disease) T-cell Mycosis fungoides Peripheral T-cell Anaplastic large cell Many more NK-cell Aggressive NK-cell leukemia Extranodal NK-cell lymphoma Complete list is in Robbins, p. 668
Molecular features of diseases Determined using specialized ancillary techniques Immunophenotyping Molecular studies by PCR or Southern blot analysis Cytogenetics Require special tissue handling
Immunophenotyping techniques Immunoperoxidase stains Indirect antibody reaction Avidin-biotin conjugate detection method Frozen or fixed, paraffin-embedded tissue Flow cytometry Direct antibody reaction Fluorescently-labeled antibodies Fresh, viable tissues
Cellular antigen and antibody reactions CD25 CD19 CD79 CD49 CD20 Anti-CD20 antigen receptor molecules adhesion molecules Structural proteins CD20 cytokines enzymes cytokine receptors
Cluster Designation (CD) nomenclature The system used for naming leukocyte surface molecules, as identified by monoclonal antibodies. Cluster Designation (CD) number CD45 Leukocyte Common Antigen (LCA) CD34 CD2, CD3, CD4, CD5, CD7, CD8 CD19, CD20 CD10 CD30 CD11c, CD13, CD14, CD15, CD33, CD117 CD61 Cell type All white blood cells Stem cells T-cells B-cells Early lymphoid cells, especially B-cells Activated lymphocyte Myeloid cells Megakaryocytes
Anaplastic large cell lymphoma, ALK positive Immunoperoxidase stain for ALK protein (CD246) showing cytoplasmic staining
Flow cytometry Fluidics Cells in suspension flow in a single -file through an illuminated volume... Optics where they scatter light and emit fluorescence that is collected and filtered... Electronics then converted to digital values that are stored on a computer.
Molecular studies for clonal gene rearrangements Hematolymphoid malignancies are clonal Neoplastic cells are derived from a single genetically altered cell The genetic alteration in the first transformed cell is carried in each of the cells derived from the first one The genetic alteration serves as a clonal tumor marker
Molecular studies for clonal gene rearrangements Lymphoid cells have lineage-specific surface proteins B-cells: Immunoglobulin heavy and light chains T-cells: T-cell receptor chains Figure: Pan et al, Neoplastic Hematopathology
Studies for clonal gene rearrangements PCR-based assays Immunoglobulin heavy chain, TCR- γ chain Can be performed on fresh, frozen or fixed tissues Assays are limited by number of primers 2-5 days to complete Southern blot analysis Immunoglobulin heavy or light chain, TCR-β chain Require fresh or frozen tissue 7-10 days to complete Flow cytometry analysis Immunoglobulin light expression, TCR-β chain expression Requires fresh viable cells Several hours to complete
Clonal genetic abnormalities detected by cytogenetic analysis Karyotyping Numeric abnormalities Translocations Fluorescence in situ hybridization using probes directed at specific genes Numeric abnormalities Translocations NPM-ALK rearrangement t(2;5)(p23;q32)
Cytogenetic abnormalities detected by molecular studies Molecular analysis by PCR to detect RNA or DNA encoding the protein product of a translocation Bcr-abl (Chronic myelogenous leukemia) PML-RαRα (Acute promyelocytic leukemia) Bcl2-IgH (Follicular lymphoma)
Case Study
Clinical presentation 26 year old female with a 2-week history of an illness characterized by high fever. Treated with levofloxacin and rapidly developed a diffuse exfoliative rash. Physical Exam: Very sick young female Diffuse exfoliative rash Edema Hepatomegaly, splenomegaly Diffuse lymphadenopathy
Laboratory findings Laboratory evaluation: Significant peripheral blood eosinophilia and lymphocytosis with atypical lymphocytes on the peripheral blood smear High LDH Abnormal liver function tests Presumptive clinical diagnosis: Lymphoma An excisional lymph node biopsy was performed Clinical history provided with the biopsy was Adenopathy, rule out lymphoma.
Lymph node biopsy Effacement of normal nodal architecture by cytologically abnormal T-cells CD3+, CD5+, admixture of both CD4+ and CD8+, numerous CD30+ large lymphocytes Focal necrosis with a mixed inflammatory cell background plasma cells, small lymphocytes, histiocytes, some granulomas Preliminary diagnosis: Atypical lymphoid proliferation suspicious for, but not diagnostic of, T-cell lymphoma. Await results of ancillary studies
Ancillary studies Cytogenetic studies: 46XX T-cell gene rearrangement studies: PCR for TCR- γ chain gene- Negative Southern blot for TCR-β chain gene- Negative Immunophenotyping of peripheral blood by flow cytometry: No phenotypically abnormal lymphoid population
Case Study: Final biopsy diagnosis Final pathologic diagnosis: Atypical lymphoid proliferation Insufficient evidence for a diagnosis of lymphoma Consider other diagnostic possibilities such as an atypical drug reaction
Case Study: More history! By then, she had been referred to an oncologist Provided additional history Patient started on carbamazepine (Tegretol) for neuralgia about 2 months prior to illness
Case Study: Carbamazepine hypersensitivity syndrome Rare Can also be seen with other anti-epileptics Fever, skin rash, hepatomegaly, splenomegaly, lymphadenopathy, other organ involvement Histologic changes and immunophenotype can mimic T-cell lymphoma Resolves in several weeks after discontinuing drug Drug was discontinued and the patient recovered!
Case Study: Take home lessons The evaluation of a patient for cancer requires Taking a careful history Underlying diseases, smoking and alcohol use, occupational exposures, familial cancer predisposition Drug history Performing a careful physical exam Obtaining an adequate tissue biopsy with sufficient tissue for all necessary ancillary studies Effective communication between the clinician, the surgeon, and the pathologist
Case Study: Take home lessons Primum non nocere