Table 1.

World Health Organization (WHO) diagnostic criteria for primary myelofibrosis [7].

Major criteria

(1) Presence of megakaryocyte proliferation and atypia, usually accompanied by either reticulin and/or collagen fibrosis, or, in the absence of significant reticulin fibrosis, the megakaryocyte changes must be accompanied by an increased bone marrow cellularity characterized by granulocytic proliferation and often decreased erythropoiesis (ie, prefibrotic cellular phase disease (2) Not meeting criteria for PV, Chronic myeloid leukemia, myelodysplastic syndrome, or other myeloid neoplasm (3) Demonstration of the JAK V617F or other clonal marker, or in the absence of clonal marker, no evidence the underlying fibrosis is due to underlying inflammatory or other neoplastic process

Minor criteria

-Leukoerythroblastosis -Increased LDH -Anemia -Palpable splenomegaly

Diagnosis requires all 3 major criteria AND 2 minor criteria.