essential thrombocythemia


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  • Criteria

    • sustained thrombocytosis of 450 E9
    • increased large megakaryocytes, normal granulopoiesis and erythropoiesis
    • rule out PCV, PMF, CML, MDS, other myeloid neoplasm
    • JAK2 V617F or rule out reactive thrombocytosis

  • Post-ET MF criteria

    • required: ET diagnosis and marrow fibrosis 2/3 or 3/4
    • additional (2/5)
      • anemia
      • leukoerythroblastosis
      • splenomegaly (new or increasing)
      • increased LDH
      • at least 2 of wt loss (10%, 6 mo), night sweats, fever (unexplained)

  • Morphology

    • blood: thrombocytosis, giant platelets
    • marrow: giant megakaryocytes with hyperlobated (stag-horn) nuclei

  • Molecular

    • JAK2 V617F in 40-50%
    • CALR in 30% of JAK2 negative cases
    • MPL in 5%
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