Congenital External Auditory Canal Cholesteatoma Resected by a Transcanal Endoscopic Approach.

Abstract

To describe the first case of congenital external auditory canal cholesteatoma resected via a transcanal endoscopic approach and describe the possible pathologenesis of cholesteatoma. A 2-year-old female patient presented with a cholesteatoma that extended from the floor of the external auditory bony canal to the inferior quadrant of her right tympanic membrane. Otological examinations and computed tomography were performed. The cholesteatoma was resected using a transcanal endoscopic approach. Pathologic examination confirmed the diagnosis of external auditory canal cholesteatoma. The patient's postoperative hearing was observed to be normal. Cholesteatoma did not recur during the 2-year follow-up period. Computed tomography scan revealed an isodense mass, partly surrounded by bony tissue, on the floor of the external auditory canal, outside of the inferior quadrant of an intact tympanic membrane. A minor malformation of the bony tissue, covering the inferiolateral surface of the cholesteatoma, was observed. The proposed mechanisms of pathogenesis are: 1) the embryonic developmental deficits of the meatal plug, during its differentiation into squamous epithelium, cause the arrest of ectodermal tissues, 2) a remnant of the squamous epithelium becomes trapped in the niche of the foramen tympanicum. A rare case of congenital external auditory canal cholesteatoma, located on the inferior external auditory canal, was diagnosed and resected using a transcanal endoscopic approach. It was possibly caused by a minor anomaly of the first branchial cleft or by a remnant of the squamous epithelium trapped in the foramen tympanicum.