[Neurinoma of tympanic plexus: a case report]

We report a unique case of neurinoma originating from the tympanic plexus. A 23-year-old man reparting hearing impairment was found in otoscopic examination to have a tumor contour identified through the ear drum. Computed tomography showed that the tumor extended from the hypotympanum to the mesotympanum, eroding the promontory. A small specimen obtained after myringotomy indicated neurinoma. The man did not report facial weakness or taste disturbance. When we operated to remove the tumor, we found the long crus of Incus had disappeared and the stapes superstructure was dislocated upward due to the tumor expanse. Pathologically, the extirpated tumor was neurinoma of Antoni A. A postoperative salivary gland function test using Tc showed hypofunction at the lesion side of the parotid gland. We surmise that neurinoma originated from the tympanic plexus because of its location and its lack of a relationship to the chorda tympanic nerve or facial nerve.