Mucous Retention Cyst of Mastoid Bone Mimicking Cholesteatoma

Abstract

A 32-year-old man presented with a 10-year history of left-sided hearing loss and otorrhea. The otorrhea had turned purulent 6 months earlier. He had suffered from chronic otitis media for 10 years and had under-gone tympanomastoidectomy 5 years earlier. He de-nied tinnitus and vertigo. Otoscopic examination revealed a 2-mm perforation on the posteroinferior quadrant of the left tympanic membrane with purulent, foul-smelling fluid. The right ear was normal. Audiometry showed pro-found mixed hearing loss in the left ear. To evaluate the mastoid bone and middle ear cavity, computed tomography (CT) scans were performed that revealed an infiltrative, irregular, hypodense, heterogeneous,