Résumé
Smooth muscle tumor of the uveal tract is rare, and mostly located in the ciliochoroidal area. We report a unique case of posterior choroidal leiomyoma in a 27-yr-old man. Ophthalmoscopic examination disclosed an 11 mm-sized mass on the fundus two-disc diameters apart from the optic disc. With a suspicion of amelanotic melanoma, the globe was enucleated. The mass occupied the whole thickness of choroidal stroma beneath the pigmented retinal epithelium and composed of spindle cells arranged in intersecting fascicles. Immunohistochemical studies demonstrated immunoreactivities of the tumor cells for smooth muscle actin, desmin, and vimentin. Ultrastructurally, numerous intracytoplasmic filaments with fusiform focal densities, scattered segmental external laminae, subplasmalemmal densities, and pinocytic vesicles were noted. The leiomyoma in this case had several unusual features in that it was confined to the posterior choroid with no relation to the ciliary body, occupied the whole stroma of the choroid instead of suprauveal location, and occurred in a young male. It is important to include choroidal leiomyoma in the differential diagnosis of choroidal tumors.