Acquired Brown's syndrome caused by frontal sinus osteoma

A 32-year-old man had a history of acquired Brown's syndrome associated with diplopia, proptosis, downward displacement of the globe, and lid edema. A CT scan of the orbit revealed an osteoma arising from the left frontal sinus and extending into the left orbit. After surgical extirpation the proptosis and diplopia disappeared and the globe returned to normal. To our knowledge, such a case has not been reported previously.