To the Editor: Irrigation of the external ear canal to remove cerumen is a frequent medical practice. It is usually safe, but can result in damage to the external, middle, and even inner ear. Trauma to the delicate squamous epithelium lining the external ear canal may expose the subcutaneous tissue to bacterial invasion,1 resulting in invasive external otitis, one of the most serious infections of the external ear. This aggressive form of external otitis almost always occurs in elderly, diabetic, or immunocompromised patients. The disease begins as an innocuous infection of the squamous epithelium of the external ear canal, but.