Reactive thrombocytosis: an early manifestation of Takayasu arteritis.

A woman with Takayasu arteritis is reported who presented with constitutional symptoms and persistent thrombocytosis documented since 3 years before the diagnosis. Disease-specific symptoms such as arm claudication, transient loss of vision, and self-remitting eye ptosis present at the time were apparently missed, because she is a non-English-speaking Hispanic woman whose history was obtained through an interpreter. Extensive workup done at the time failed to reach a definite etiology. A computed tomography scan of the chest done because of midthoracic back pain and an elevated erythrocyte sedimentation rate showed circumferential wall thickening and mild surrounding edema throughout the thoracic and abdominal aorta and both carotid arteries consistent with Takayasu arteritis. Prednisone at a dosage of 1 mg/kg twice a day decreased the platelet count within 45 days of its initiation. Takayasu arteritis should be considered in the differential diagnosis of unexplained thrombocytosis, particularly in young women.