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The WHO Classification of Hematological Malignancies Pathology Grand Rounds April 11 2001.

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Presentation on theme: "The WHO Classification of Hematological Malignancies Pathology Grand Rounds April 11 2001."— Presentation transcript:

1 The WHO Classification of Hematological Malignancies Pathology Grand Rounds April

2 No, its not that kind of Who

3 So what is it? Classification that includes myeloid, lymphoid, histiocytic and mast cell neoplasms applies the principles of the REAL classification to hematological neoplasms –morphology –immunophenotype –genetic features –clinical features

4 WHO classification of myeloid neoplasms Myeloproliferative disease (MPD) Myelodysplastic/Myeloproliferative disease Myelodysplastic disease (MDS) Acute myeloid leukemia (AML) –AML w/recurrent cytogenetic translocations –AML w/ myelodysplasia-related features –Therapy-related AML and MDS –AML not otherwise categorized

5 Myeloproliferative Disease clonal stem cell disorder with effective hematopoiesis resulting in elevated peripheral blood cells and hepatosplenomegaly –Ph1 + CML –polycythemia vera –idiopathic myelofibrosis –essential thrombocytopenia

6 Juvenile myelomonocytic leukemia (JMML) distinct from adult CML or CMML classified as a MDS/MPD lack Ph1 or BCR/ABL translocation usually <3 years old at diagnosis dysplasia present but not prominent

7 Chronic myelomonocytic leukemia (CMML) some patients with MDS features - normal PMN counts, multilineage dysplasia, no organomegaly, and BM morphology of RAEB with monocytosis some patients with MPD features - neutrophilia, monocytosis, and splenomegaly classified as MDS/MPD

8 Atypical CML (aCML) lack Ph1 or BCR/ABL translocation predominantly neutrophil series dysplastic as well as proliferative features often multilineage dysplasia worse prognosis than Ph1 + CML classified as MDS/MPD

9 Refractory cytopenia with multilineage dysplasia (RCMD) RA and RARS (FAB) - dysplasia is largely limited to erythroid lineage MDS with <5% blasts but multilineage dysplasia have worse prognosis and are more likely to die of marrow failure or progress to acute leukemia (like RAEB) Multilineage dysplasia is defined as dysplastic features in the cells of two or more cell lines

10 What blast count should define AML? Recent studies have shown that patients with 20-30% blasts (RAEB-T) have similar prognosis to those who have >30% blasts (AML) WHO - AML is defined as >20% blasts RAEB-T category dropped

11 Cytogenetic/molecular categories of AML specific cytogenetic abnormalities do not correlate precisely with FAB categories these should be recognized as distinct entities include low blast count cases previously categorized as MDS (<20% blasts) currently include four categories

12 Cytogenetic/molecular categories of AML AML with t(8;21)(q22;q22),AML1(CBF )/ETO Acute promyelocytic leukemia (AML with t(15;17)(q22;q11-12) and variants, PML/RAR ) AML with abnormal bone marrow eosinophils (inv(16)(p13q22) or t(16;16)(p13;q11), CBF /MYH11X) AML with 11q23 (MLL) abnormalities

13 Dysplasia and AML multilineage dysplasia associated with poor outcomes –dysplasia in two or more cell lines history of prior MDS associated with poor outcomes

14 Prior therapy and AML- Alkylating agents different from de novo AML associated with characteristic cytogenetic alterations –3q-, -5, 5q-, -7, 7q-, +8, +9, 11q-, 12p-, -18, -19, 20q-, +21, t(1;7), t(2;11), and complex karyotypes associated with a worse prognosis

15 Prior therapy and AML- Topoisomerase II inhibitors epipodophyllotoxins and adriamycin associated with secondary leukemias (may be lymphoid) associated with cytogenetic abnormalities of de novo AML –11q23 (MLL), occ. t(8;21), inv(16) or t(15;17)


17 Lymphoid neoplasms WHO adopted the REAL classification with minor modifications split some categories adopted some provisional categories as real

18 Lymphoblastic neoplasms dropped FAB L1, L2, L3 terminology ALL and lymphoblastic lymphoma single disease group by cytogenetic abnormalities –t(9;22)(q34;q11); BCR/ABL –t(v;11q23); MLL rearranged –t(1;19)(q23;p13) E2A/PBX1 –t(12;21)(p12;q22) ETV/CBF

19 Follicular lymphoma changed nomenclature from follicle center lymphoma to follicular lymphoma in the rare case of a purely diffuse lymphoma of follicle center cell origin retain the term follicle center lymphoma, diffuse –BCL2 –CD10

20 Grading follicular lymphoma grade 1 and 2 are similar - grade 3 has earlier relapses use Berard cell counting method for grade grade 1: 0-5 centroblasts/hpf grade 2: 6-15 centroblasts/hpf grade 3: >15 centroblasts/hpf –3a - centrocytes still present –3b - no centrocytes

21 Reporting diffuse areas should be reported and quantified as per ILSG recommendations –predominantly follicular - >75% follicular –follicular and diffuse % follicular –predominantly diffuse - <25% follicular areas of DLBCL should be reported separately –e.g. follicular lymphoma grade 3 (75%) with DLBCL (25%)

22 Large cells in marginal zone/MALT lymphomas recent studies suggest increased transformed cells (5-10% with clusters >20 cells) conferred a slight but significantly worse prognosis if DLBCL coexists a separate diagnosis should be made

23 Mantle cell lymphoma mantle zone pattern is less aggressive blastic morphology has worse prognosis since no effective treatment morphologic subtyping is not required but encouraged for research purposes

24 Diffuse large B-cell lymphoma no biological or clinical data to support subtyping

25 Burkitts vs. Burkitts-like lymphoma Burkitts-like is a non-reproducible category DDx - Burkitts and DLBCL reserve Dx of Burkitts-like for high grade lymphomas –morphologically resembles Burkitts –has more pleomorphic or large cells than classical Burkitts –Ki-67 proliferative fraction >99%

26 ALCL definition ALK+ and/or t(2;5) - relatively good prognosis not restricted to ALK + cases ALK should be performed on all cases to the extent possible

27 Cutaneous vs. systemic ALCL cutaneous ALCL –indolent course –lack t(2;5)(p23;q35) –ALK negative –form spectrum with lymphomatoid papulosis

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