[Possible ectopic cerebral tissue in the middle ear--a case report].

A 58-year-old woman suffered from chronic otitis media with possible ectopic cerebral tissue on the aditus ad antrum and the epitympanum. This 6 x 2 mm ectopic brain mass was removed carefully after discontinuity between this mass and intracranial cerebral tissue was detected. By histopathological examination, this possible ectopic cerebral mass was found to include mucous glands of middle ear mucosa. An exposed area of the dura mater 2 mm in diameter was found at the tagmen of the mastoid cavity and the aditus ad antrum, but there was neither perforation of the dura nor cerebrospinal fluid leakage from my part of the dura. This patient has not experienced any trouble during the one year post-operative course, and she obtained about a 15 dB hearing improvement in the ten months after surgery when compared with her preoperative status.