Granular cell tumor (myoblastoma) of the orbit.

An 8-year-old white boy had a tumor in the left orbit with clinical manifestations of muscular impairment, exophthalmos, and reduced visual acuity. Five months after exenteration of the orbit the boy was healthy without tumor recurrence. Based on our observations with electron, light, and phase microscopy, and histochemical studies, we conclude that this tumor is benign, of histiocytic origin, and we propose the term granular cell histiocytoma be used to describe this entity.