Exostosis

Unquestionably, gentlemen, the bones most liable to exostosis are, first, the femur; secondly, the humeri; and thirdly, the lower jaw. But exostoses are met with on the sternum clavicle, and the bones of the head; in short, I may state, that there are no bones on which exostoses may not be produced.

Exostoses are the most common benign tumors of the EAC.^([External Auditory Canal])

2013, Quinton Gopen, Fundamental Otology: Pediatric & Adult Practice, Jaypee Brothers Medical Publishers, page 381, Part of the issue is the exostoses themselves, which can lead the surgeon directly into normal important structures. The exostosis may grow medially and become in direct contact with the tympanic membrane. The exostosis may also grow medial to the annular insertion of the tympanic membrane, placing the facial nerve at significant risk.