[Chorea revealing a polycytemia vera]

Neurological manifestations in polycytemia vera are common. However, chorea is an exceptionally revealing feature of this disease. We report a 78-year-old man who presented with headache and an abnormal movement disorder corresponding to chorea. Laboratory findings showed increased levels of hemoglobin at 20 g/dl and hematocrit at 62.3%. An elevated erythrocyte mass to twice the normal value demonstrated the absolute erythrocytosis. A JAK2 V617F gene mutation was identified. A diagnosis of polycytemia vera-associated chorea was obtained. Clinical and biological outcomes were favorable after therapeutic phlebotomy and treatment with hydroxyurea. We recommend a complete blood cell count in elderly patient presenting with chorea to eliminate a diagnosis of polycytemia vera.