Cartilaginous Choristoma of the External Auditory Canal

Abstract

Choristoma, a subtype of heterotopia, represents the presence of histologically normal tissue at an embryologically aberrant site. The finding of a heterotopic cartilaginous mass within the bony external auditory canal is an uncommon occurrence. We report a case of cartilaginous choristoma in a 5-year-old male patient. Otoscopic examination demonstrated a round, white, firm mass located on the anterior wall of the external auditory canal, covered by normal-appearing epithelium. Palpation using a ball-probe revealed firm and non-tender lesions, raising suspicion for osseous or cartilaginous masses rather than soft tissue tumors. The mass was surgically excised through a transcanal approach. Histologically, the mass was composed of mature cartilage without any neoplastic characteristics. This case emphasizes the necessity of considering choristoma in the differential diagnosis of a white mass seen lateral to an intact tympanic membrane.