Giant, mushroom-shaped osteoma of the orbit originating from the maxillary sinus.

A 53-year-old woman had a six-month history of proptosis, pain, and decreased vision in the right eye. Skull X-ray films and polytomography demonstrated a giant, mushroom-shaped osteoma originating from the roof of the maxillary sinus and invading the orbit. The tumor was removed by a lateral orbital approach with prompt resolution of proptosis and pain, and recovery of normal vision and ocular motility. This patient is one of 34 patients with 38 paranasal sinus osteomas examined here in the last 25 years. Only six patients have had orbital symptoms or signs.