Epithelioid hemangioma of the temporal artery clinically mimicking temporal arteritis

A rare case of epithelioid hemangioma (angiolymphoid hyperplasia with eosinophilia) arising in the right temporal artery of a 68-year-old Japanese woman was investigated. The patient had been treated with corticosteroids (Predonine 5 mg/day p.o.) for 4 years for idiopathic thrombocytopenic purpura. Headaches in the right temporal region with repeated high fevers first appeared 1 year prior to the biopsy of a nodule at the artery. The clinical diagnosis was temporal arteritis (giant cell arteritis). The specimen consisted of a short segment of the superior arterial branch having a sheet-like proliferation of the epithelioid endothelial cells in the lumen, which was almost occluded, focal rupture of the media, and marked proliferation of the capillaries (neovascularization) radiating out from the media to the adventitia. There were scattered foci of inflammatory cell infiltration composed mainly of small lymphocytes in the adventitia, but there were no histological changes suggestive of giant cell arteritis. The lesion was thus characterized by the proliferation of epithelioid endothelial cells in the lumen of the artery, and neovascularization between the media and adventitia. The histological features were very close to epithelioid hemangioma except for the absence of an eosinophilic reaction. The long-term administration of corticosteroids may have suppressed it. The authors believe this is the first case of epithelioid hemangioma arising from the temporal artery without a history of trauma. It showed some unique features both clinically and histopathologically, which contributed to the study of the yet not clearly classified vascular proliferative lesion, epithelioid hemangioma.