Keratosis obturans and external ear canal cholesteatoma: how and why we should distinguish between these conditions.

Keratosis obturans and external ear canal cholesteatomas have been considered as separate entities for the last 20 years, after being regarded as variations of the same disease for at least 87 years. While both disorders are distinct, they do have some overlapping characteristics which may make it difficult to reach a definite diagnosis. This review explores the diagnostic dilemmas which may arise, and discusses the classification, aetiology, pathogenesis and management of these conditions. We concur that external ear canal cholesteatoma and keratosis obturans are different conditions and conclude that the presence of osteonecrosis and focal overlying epithelial loss are the most reliable features favouring the diagnosis of external ear canal cholesteatoma over keratosis obturans. Furthermore, whilst keratosis obturans can be managed successfully by regular aural toilet, external ear canal cholesteatoma may require surgical intervention depending on the extent of the disease.