Probably the most common benign tumors that we will see are ceruminous gland adenomas which look like little blue blisters in the ear canal. (allfelinehospital.com)
Demodex canis infection can also cause ceruminous otitis externa. (2ndchance.info)
Castrated (spayed) male dogs have a predilection for developing ceruminous carcinomas. (wearethecure.org)