Chronic otitis externa: Chronic inflammation of the skin lining the external ear canal leading to the ear drum. Can be caused by a number of problems including bacterial infection, a chronic skin disorder (eczema or seborrhea), fungus (Aspergillosis), chronic irritation (hearing aids, Q-tips), allergy, chronic drainage from middle ear disease, a tumor (rare), or it may simply be due to a nervous habit of frequently scratching the ear.
More than one factor may be involved. For example, a patient with eczema may subsequently develop black ear drainage. This would be suggestive of an accompanying fungus.
In diabetics or immune-suppressed individuals, chronic external otitis can become a very serious disease (malignant external otitis). Malignant external otitis is a misnomer because it is not a tumor or a cancer, but rather an aggressive bacterial (Pseudomonas) infection of the bone that can lead to infection of the base of the skull.