Proptosis from maxillary sinus inverted papilloma with malignant transformation.

We describe a 58-year-old woman who presented with proptosis, upward displacement, and decreased vision in her right eye. A computed tomography scan revealed a mass filling the right maxillary sinus, destroying bone and invading the inferolateral orbit. The tumor proved to be an inverted squamous papilloma with focal transformation to squamous cell carcinoma. Although a rare cause of proptosis, inverted papilloma with orbital invasion must be considered when a patient describes associated nasal or sinus disease.