상고실 진주종으로 오인된 상고실 연골성 분리종 1예

A case of cartilaginous choristoma in epitympanum, presenting as attic cholesteatoma

Choristoma, a type of heterotopia, is a rest of histologically normal tissue in an embryologically abnormal site. Although cartilaginous choristoma of bony external auditory canal has been found often, it is rare in the middle ear cavity. Because of the similarity of shape and color with cholesteatoma and the infrequency of middle ear choristoma, the diagnosis is unsuspected until surgical pathology is obtained. We report a case of attic cartilaginous choristoma in 21-year-old man. Initial diagnosis was attic cholesteatoma and surgical removal was done via transcanal approach. Histologically, it consists of mature cartilage without neoplastic features. This case highlights the importance of considering choriostoma when white mass is seen behind intact tympanic membrane and its feature looks like cholesteatoma.