Essential thrombocythemia (ET) is a rare myeloproliferative neoplasm involving abnormalities in megakaryocytes, allowing them to over-proliferate in the bone marrow. This disorder presents with markedly elevated platelet counts, typically greater than 600 x 109/L, but very often greater than 1000 x 109/L, although these platelets are often dysfunctional.
Even though the megakaryocyte lineage is always affected, leukocyte and erythrocyte lineages can also show increases as well.
Increased incidence of ET has been reported in age groups from 20-30 years old and from 50-60 years old. Women are more likely than men to develop the condition.
