ORBITAL DERMOID CYSTS LOCATED WITHIN THE LATERAL RECTUS MUSCLE

Background: Two patients, a 13-year-old girl and a 31-year-old man, ha d an orbital dermoid tumor located in the lateral rectus muscle. This unusual location of dermoid tumors has not been reported previously. M ethods: Computed tomography and magnetic resonance imaging showed a cy stic mass within the belly of the lateral rectus in each patient. Surg ical excision through a lateral orbitotomy showed a well-circumscribed mass surrounded by lateral rectus fibers. No periorbital attachment w as noted. Results: Results of histopathologic evaluations showed a der moid cyst. Postoperatively, the diplopia and proptosis resolved. In on e patient, an unusual subconjunctival deposition of fat droplets was s een. Conclusion: The findings in patients demonstrate an unusual prese ntation of dermoid cysts and make an addition to the differential diag nosis of enlarged extraocular muscles.