Ceruminous adenocarcinoma is a malignant neoplasm derived from ceruminous glands of the external auditory canal. This tumor is rare, with several names used in the past.[3][4] Synonyms have included cylindroma, ceruminoma, ceruminous adenocarcinoma, not otherwise specified (NOS), ceruminous adenoid cystic carcinoma (ACC),[1][2] and ceruminous mucoepidermoid carcinoma.