Chronic myeloproliferative disorder, persistent increase in platelet count. About half of cases are discovered incidentally on FBC and the other half become symptomatic – typically with thrombus formation.
- Associated with thrombotic or haemorrhagic complications, average age 60 years
- Good prognosis, risk of transformation to myelofibrosis and AML
- Symptoms: may be asymptomatic, burning on the soles and palms, cold peripheries, headache, dizziness
- Occlusion of arterioles: ischaemia, gangrene or acrocyanosis.
- Haemorrhagic complications: ecchymosis, epistaxis, menorrhagia and GIT haemorrhage.
- Splenomegaly unusual, may be painful splenic infarction
- Platelet count usually >600×109/l
- Diagnosis of exclusion (rule out infection, inflammation, iron deficiency, malignancy)
- Investigations: normal ESR, plasma viscosity and fibribnogen levels
- 50% have acquired JAK2 mutation.
- Bone marrow examination: exclude CML, myelofibrosis and myelodysplasia, check iron stores
- Treatment: hydroxycarbamide and aspirin is given in high risk cases (elderly, platelets >1500×109/l or previous thromboembolic events)
- Low-dose asprin alone in lower risk patients, interferon given in pregnancy
