Essential Thombocythaemia

persistent elevation of blood platelet count as a result of increased marrow production in absence of systemic cause of thrombocytosis

Aetiology

• related to polycythaemia rubra vera

  • occurs in younger adults

Clinical features

• asymptomatic (20%)
• thrombosis
  • arterial
  • venous
• excessive haemorrhage
  • spontaneously
  • after trauma / surgery
• Splenomegaly - 30%, may also be infarcted
• pruritus, sweating (uncommon)

Laboratory findings

• Platelets >1000 x 10⁹/L persistently
• Raised RBC or WCC (30%)
• Film
  • anisocytosis
  • circulating megakaryocyte fragments
  • target cell
  • Howell-Jolly bodies
• NAP score raised or normal
• Serum uric acid (often) / LDH (sometimes) raised
• Bone Marrow hypercellular
• Defective platelet function esp. in response to ADP and adrenaline

Treatment

• Hydroxyurea (or other chemotherapy)
  • aim for platelet count <600 x 10⁹/L
• alpha-interferon, anagrelide
• Aspirin 75mg OD, unless haemorrhage

Prognosis

• median survival 20 years
• transformation to AML may occur

[ Home ] [ Up ]