Essential thrombocythaemia

Essential thrombocythaemia (ET) is a myeloproliferative neoplasm characterised by proliferation of the megakaryocyte lineage only.

50% of ET cases are associated with JAK2 mutation. The remaining cases are caused by CALR or MPL mutations.

Clinical features

Most are asymptomatic. Symptoms are related to thrombotic or haemorrhagic episodes.

Diagnosis and evaluation

Labs show:

• Normal Hct
• Normal RBC
• Normal WBC
• Elevated thrombocytes

Blood smear shows large hypogranular platelets. Bone marrow biopsy shows megakaryocytic proliferation. Genetic testing for driver mutations confirms the diagnosis.

Treatment

The basic treatment is aspirin to prevent thrombosis. If there is a history of thrombosis or the patient is >60 years, cytoreductive therapy is also indicated. This involves cytoreductive drugs like hydroxyurea, anagrelide, or pegylated interferon.