Orbital dermoid cysts located within the lateral rectus muscle.

Abstract

Two patients, a 13-year-old girl and a 31-year-old man, had an orbital dermoid tumor located in the lateral rectus muscle. This unusual location of dermoid tumors has not been reported previously. Computed tomography and magnetic resonance imaging showed a cystic mass within the belly of the lateral rectus in each patient. Surgical excision through a lateral orbitotomy showed a well-circumscribed mass surrounded by lateral rectus fibers. No periorbital attachment was noted. Results of histopathologic evaluations showed a dermoid cyst. Postoperatively, the diplopia and proptosis resolved. In one patient, an unusual subconjunctival deposition of fat droplets was seen. The findings in patients demonstrate an unusual presentation of dermoid cysts and make an addition to the differential diagnosis of enlarged extraocular muscles.