Proptosis with mastication: an unusual presentation of an orbital dermoid cyst.

A 25-year-old woman presented in 1973 with the complaint of proptosis of the left eye with mastication. A firm retrobulbar orbital mass was detected, and diagnosis of possible dermoid cyst was made. She was subsequently lost to follow-up. Computed tomographic (CT) scanning and surgical excision done in 1984 confirmed the presence of an orbital dermoid cyst communicating with the temporal fossa through a bony defect in the lateral orbital wall. We suspect that pressure by the temporalis muscle on the dumbbell-shaped cyst caused the proptosis with mastication.