polycythemia vera


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  • General

    • median age 60
    • site: blood + marrow, later involves spleen and liver
    • can progress: PCV -> MDS -> AML
    • 95% JAK2

  • Phases

    • pre-polycythemic (prodromal)
      • blood: mild erythrocytosis, thrombocytosis
      • marrow: mild hypercellular with trilineage proliferation: erythroid, granulocytic, and megakaryocytic
      • can mimick ET, giant hyperlobated megakaryocytes
    • polycythemic
      • blood: overt erythrocytosis
      • marrow: hypercellular, trilineage proliferation
        • characteristic hypercellularity in subcortical space (normally hypocellular)
        • pleomorphic megakaryocytes
    • post-polycythemic myelofibrosis (spent phase)
      • blood: anemia, tear drop cells, poikilocytes, leukoerythroblastosis
      • marrow: myelofibrosis, decreased erythroids and granulocytes, megakaryocyte proliferation
        • dysmorphic megakaryocytes
        • increased blasts = PCV -> MDS -> AML
      • splenomegaly, extramedullary hematopoiesis

  • Criteria

    • requires 2 major + 1 minor, or 1st major + 2 minor
    • major
      • Hgb > 18.5 (male), 16.5 (female)
      • JAK2 mutation (V617F, exon 12)
    • minor
      • hypercellular marrow with trilineage proliferation
      • low EPO
      • endogenous erythroid colony formation in vitro

  • Criteria (spent phase)

    • required
      • previous diagnosis of PCV
      • marrow fibrosis grade at least 2/3 (or 3/4)
    • plus 2 of the following
      • anemia
      • leukoerythroblastic in peripheral blood (immature granulocytes, nucleated reds)
      • splenomegaly
      • 2 of: wt loss (10%, last 6 mo), night sweats, fever
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