External auditory canal cholesteatoma

External auditory canal cholesteatoma (EACC) is an uncommon otologic entity. The predominant findings are erosion of the bony structure of the external auditory canal and accumulation of keratin debris. Microscopic examination of the ear after meticulous removal of wax, especially in elderly patients, is useful in detecting EACCs. Irreversible damage is often caused by diffuse cholesteatomas because of the difficulty of observing conditions in the stenosed ear canal and the absence of early symptoms and signs of this disease. Because of the insidious nature of EACC and the proximity of the external auditory canal to important structures, the possibility of EACC should be always considered in differential diagnosis for lesions of the external auditory canal. We report a case of a 58-year-old woman in whom an EACC invaded the mastoid bone. There was no recurrence of the EACC in the postoperative follow-up. This case highlights the importance of early surgical treatment of EACCs and regular follow-up examinations.