Respiratory epithelial orbital cysts.

Congenital or post-traumatic respiratory epithelial lined cysts of the orbit are very rare, and such cysts more commonly occur as mucocoeles secondary to chronic paranasal sinus disease. Four new cases of such cysts are described herein, three presumed choristomas and one occurring after trauma. Two of three presumed choristomatous (congenital) cysts occurred in sites that were atypical for the commoner dermoid cyst. One occurred in the superior orbit between the superior rectus and levator palpebrae superioris muscle and one in the temporal fossa and lateral orbit. The third choristomatous lesion occurred in the superotemporal orbit with a well-defined bony defect, a typical pattern of the commoner dermoid cyst. The fourth case, a presumed traumatic respiratory epithelial cyst, probably arose from ethmoidal sinus mucosa. Respiratory epithelial orbital cysts are very rare and may occur in sites that are atypical for the commoner orbital dermoid cyst.