Irritated seborrheic keratosis of the external ear canal.

Although a seborrheic keratosis is not rare on the skin of the trunk, extremities, head and neck of an elderly person, it is uncommon to originate in the external ear canal. Even rarer, an irritated subtype may arise in this location. We report the case of a 63-year-old man with an irritated seborrheic keratosis arising in the right external ear canal, who first presented with a bloody discharge from his right ear canal 3 years and 10 months before the subsequent operation. Macroscopically, a dome-like, black elevation was found at the anterior wall of the right external ear canal. A biopsy showed an exophytic papillomatous, hyperkeratotic growth of basaloid cells which revealed some nuclear atypism and mitosis. Squamous eddies and moderate inflammatory infiltrate were noted. Some cellular atypism made us suspect an irritated seborrheic keratosis. Because the patient hated the extirpation, he remained untreated for 3 years and 3 months following his first presentation. The biopsy and a surgical resection of his second presentation confirmed the diagnosis of irritated seborrheic keratosis. Immunohistochemical analysis of Ki-67, p53 and papillomavirus was performed to elucidate its character. We emphasize that irritated seborrheic keratosis does occur in the external ear canal and may cause some diagnostic difficulty. Pathologists should be aware of this fact and avoid overdiagnosis.