Basal cell carcinoma within a seborrhoeic keratosis.

In a typical seborrhoeic keratosis removed from a 79-year-old woman a smaller area with transition to basal cell carcinoma is found. Invasion from the surrounding skin may be excluded, just as a primary Pinkus' fibroepithelioma is out of the question. The possibility of secondary epithelial changes above a subepidermal fibrosis is unlikely.