A respiratory epithelial choristomatous cyst of the orbit.

A 23-year-old woman presented with a 19-year history of unilateral, intermittently painful, slowly progressive proptosis. Clinical examination disclosed decreased orbital resiliency and choroidal folds in the posterior pole. Orbital echography revealed an acoustically empty cystic lesion superotemporally. Computerized tomography demonstrated bony molding of the adjacent lateral orbital wall. At operation, a discrete, well-encapsulated mass was found adherent to the periorbita behind the lacrimal gland and extending into the muscle cone. There was no connection with the bony orbit. Histological examination disclosed the well-encapsulated cyst to be lined by pseudostratified ciliated columnar epithelium with goblet cells and filled with mucoid debris. We postulate that the cyst arose from respiratory epithelium sequestered during the intrauterine development of the paranasal sinuses.