Dehiscence of intrapetrous segment of the internal carotid artery in a dermoid cyst of the eustachian tube

Dermoid cysts are rare congenital tumors. Localization in the Eustachian tube is even less frequent. We report the case of a two-year-old girl diagnosed with a left ear dermoid cyst of the Eustachian tube. The carotid canal was dehiscent in the middle ear space. Careful interpretation of the preoperative imaging studies was important in order to prevent serious operative complications. A review of the literature concerning dermoid cysts of the Eustachian tube is also discussed.