Choroidal leiomyoma of vascular origin.

A 57-year-old man had a clinically suspected malignant melanoma in his left eye. On microscopic study, the enucleated eye harbored an unusual choroidal tumor that had extended extraocularly. This tumor had been variously interpreted microscopically as an angiosarcoma, an atpical angioma, a glioma, or a neurilemoma. Electron microscopic examination of deparaffinized tissue established the smooth muscle nature of the tumor cells as well as the presence of numerous pericytes associated with conspicuous vascular channels. This unique myogenous tumor of the choroid probably had a vascular origin.