Case reports: heterotopic brain tissue of middle ear associated with cholesteatoma.

Heterotopic brain tissue reportedly occurs occasionally in various sites, including rare occurrences in the middle ear. Association with cholesteatoma in middle ear cases, however, has not been reported yet. In this article, the authors describe three cases of heterotopic brain tissue in the middle ear associated with cholesteatoma: a 3-year-old boy with recurrent meningitis resulting in right acute otitis media and bony dehiscence of the right attic; a 36-year-old man with chronic right ear infections, right radical mastoidectomy 2 years previously, and brain herniation through the tegmen tympani; and a 65-year-old man with chronic otitis for many years, right ear surgery 25 years previously, and extensive involvement of right middle ear ossicles and mastoid antrum by cholesteatoma. The heterotopic brain tissue in each of these cases was diagnosed by histologic examination, and its glial component was confirmed by immunohistochemical staining for glial fibrillary acidic protein. After a microscopic review of 40 additional surgical pathology cases of cholesteatoma, no evidence of heterotopic brain tissue was found. With these findings, it is suggested that the unusual occurrence of heterotopic brain tissue in the middle ear associated with cholesteatoma may result from local destruction of bone secondary to the cholesteatoma, otitis media, meningitis, or previous surgery.