Acute myeloid leukaemia arising from a patient with untreated essential thrombocythaemia.

Acute myeloid leukaemia (AML) is an uncommon complication of patients with essential thrombocythaemia (ET). We report a patient with ET which progressed into AML and who had only received a few days of therapy with hydroxyurea (HU) when diagnosed with ET. This is extremely rare, as in large series no patients who were left untreated for their ET developed this complication. This case supports the theory that AML transformation can be part of the natural history of ET in some cases.