Essential thrombocythemia

Definition

• Myelodysplastic disorder of the thrombocytopoeitic stem cells causing a clonal proliferation of thrombocytes

Clinical Manifestations

• History
  • History of thrombosis or bleeding
• Signs & Symptoms
  • Digital ischemia
  • Cerebrovascular ischemia
• High risk for vascular events if:
  • History of thrombosis or bleeding
  • Increased cardiovascular risk
  • Older than 60 years

Differential Diagnosis

• Must distinguish from other myelodysplastic disorders (especially polycythemia vera) as well as from secondary causes of thrombocytosis

Management

• Acute
  • If digital or cerebrovascular ischemia, rapid cytoreduction with platelet pheresis
• Chronic
  • If high risk, requires cytoreduction and aspirin:
    • First-line: hydroxyurea
    • Alternative: anagrelide
    • Pregnancy: interferon alfa
  • If >1.5m platelets, requires cytoreduction alone