Category Archives: WHO Classification

Organ Systems, Bone Marrow, WHO Classification, Hematopathology, Acute Leukemia

Myeloid/Lymphoid Neoplasms Associated with Eosinophilia

  • PDGFA
    • Eosinophilia with increased tryptase and marrow mast cells
    • Cryptic deletion in chromosome 4q12
    • FIP1L1-PDGFA, many other partners
    • Responsive to tyrosine kinase inhibitors (e.g. imatimib/Gleevec®)
  • PDGFB
    • Eosinophilia combined with monocytosis that mimics CMML
    • t(5;12)(q31;33;p12) ETV6-PDGFB, many other partners
    • Responsive to TKIs 
  • FGFR1
    • Eosinophilia combined with AML or T-ALL
    • Associated with 8p11 translocations, FGFR1 with multiple partners
    • Not responsive to TKIs (poor prognosis)
  • PCM1-JAK2 (provisional entity)
    • Eosinophilia along with acute lymphoblastic leukemia (B-cell) or lymphoma (T-cell)
    • Bone marrow with lymphoid aggregates and increased/left shifted erythroid precursors (mimics PMF)
    • May respond to JAK2 inhibitors (e.g ruxolitinib/Jakafi®)
References

Arber DA, Orazi A, Hasserjian R, Thiele J, Borowitz MJ, Le Beau MM, et al. The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia. Blood. 2016;127: 2391–2405. doi:10.1182/blood-2016-03-643544

Swerdlow SH, Campo E, Harris, NL, Jaffe ES, Pileri SA, Stein H, Thiele J (Eds):  WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (Revised 4th edition). IARC: Lyon 2017

Organ Systems, Bone Marrow, Multiple Myeloma, WHO Classification, Hematopathology

Smoldering (Asymptomatic) Myeloma 

Smoldering (Asymptomatic) Myeloma 
  • >3 gm/dL serum M protein (or) urinary M protein ≥500 mg/24 hours
  • (and/or) 10-60% bone marrow plasma cells (usually 10-20% plasma cells)
  • Asymptomatic patients with no evidence of end-organ damage or biomarker evidence of malignancy (myeloma-defining events)

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Organ Systems, Bone Marrow, Multiple Myeloma, Lymph Node, WHO Classification, Hematopathology

Plasma Cell Neoplasms

2016 WHO Classification

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Organ Systems, Bone Marrow, Lymph Node, WHO Classification, Hematopathology

Large B-Cell Lymphomas

Organ Systems, WHO Classification, Hematopathology, Acute Leukemia

WHO 2008/2016 Criteria for Mixed-Phenotype Blasts

Myeloid

  • MPO expression (flow cytometry, immunohistochemistry, or enzyme cytochemistry) – WHO does not define thresholds for positiivity, which can result in variability between laboratories
    • Flow cytometry:  >10% (some propose 13%) expression compared to isotype control (preferred methodology)
    • Enzyme cytochemsitry:  >3% staining of blasts
    • IHC:  No well-defined cutoff (not commonly done – MPO IHC is available)

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