Polycythemia vera

on 7.2.09 with 0 comments

  • Erythroid proliferation predominates

  • Usually in middle age and more in males

  • Must be separated from relative (spurious) polycythemia from hemoconcentration and from secondary polycythemia from increased EPO secretion

    • This is best done by radiolabeling RBCs

    • In Lubbock, done by HCT

  • Diagnostic criteria (diagnosis needs either all 3 major, or 2 major and 2 minor in the absence of splenomegaly)

    • Major

      • Absolute increase in RBC mass

      • Normal arterial O2 saturation (rules out chronic hypoxia as a cause of erythrocytosis)

      • Splenomegaly (not seen in other causes of erythrocytosis…this comes from extramedullary hematopoiesis that’s going on the spleen because of the neoplastic stem cells that are there undergoing hematopoiesis)

    • Minor

      • Thrombocytosis

      • Leukocytosis (should see elevated neutrophils)

      • Elevated leukocyte alkaline phosphatase (LAP) score (this is how we can tell this apart from CML, which would have a decreased LAP score)

      • Elevated B12 level or B12 binding capacity (neutrophils are responsible for B12 transport…if they are elevated, more B12 can be bound)

  • Clinical signs

    • Plethoric congestion of tissues from increased blood volume and viscosity

      • Vascular stasis and infarction common in heart, spleen, and kidneys

      • Intense pruritis (maybe form increased release of histamine by basophils; this may also cause the increased incidence of gastric ulcers)

      • Platelet dysfunction may lead to hemorrhage of GI tract or brain

      • H/A, dizziness, GI symptoms, hematemesis, and melena are common

      • High cell turnover leads to hyperuricemia (goes on to gout in 5-15%)

    • Hyperplastic bone marrow, but serum EPO low

      • Neoplastic stem cells have increased sensitivity to EPO and other growth factors

      • Disease progression may be seen as increasing marrow fibrosis or leukemic transformation

  • Most patients are treated with therapeutic phlebotomy (leads to mean survival of 10 years); avoid chemo as long as possible (increases progression to AML to 15% [2% with phlebotomy])

  • “spent phase”

    • Marrow been working hard and shuts down

    • Begin to see increased fibrosis and decreased cellularity in the marrow

    • May see an increase in splenomegaly from myeloid metaplasia trying to make up for failing marrow

    • Start to develop peripheral cytopenias

Category: Medical Subject Notes , Pathology Notes



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