WHO diagnostic criteria for primary myelofibrosis

Last reviewed 05/2021

The following criteria have been proposed by the WHO for the diagnosis of primary myelofibrosis.

  • major criteria - requires meeting all 3 major criteria
    • megakaryocyte proliferation and atypia accompanied by either reticulin and/or collagen fibrosis, or In the absence of reticulin fibrosis, the megakaryocyte changes must be accompanied by increased bone marrow cellularity, granulocytic proliferation and often decreased erythropoiesis (ie, prefibrotic PMF)
    • not meeting WHO criteria for CML, PV, MDS, or other myeloid neoplasm
    • demonstration of JAK2V617F or other clonal marker or no evidence of reactive bone marrow fibrosis

  • minor citeria - requires meeting 2 minor criteria
    • leukoerythroblastosis
    • increased serum LDH
    • anemia
    • palpable splenomegaly

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