Seborrheic keratoses of black patients with epidermodysplasia verruciformis contain human papillomavirus DNA.

Epidermodysplasia verruciformis (EV) is a rare disease characterized by a generalized cutaneous infection with human papillomaviruses (HPVs) and a propensity for transformation of the lesions to squamous cell carcinomas on sun-exposed areas of the skin. Black-skinned patients with EV have a much lower incidence of skin cancer. Nine of 32 black African patients with EV presented deeply pigmented, flat or slightly raised lesions, located mostly in sun-exposed areas, that clinically had been diagnosed as seborrheic keratoses. Seborrheic keratoses are otherwise very rare in black Africans. Histology of these lesions disclosed seborrheic keratoses, lesions with seborrheic keratosis, and EV changes in the same biopsy specimens and seborrheic keratoses with features of bowenoid dysplasia. Reverse blot hybridization indicated the presence of DNA related to the HPV-5 group of papillomaviruses in seborrheic keratoses in three patients. Subsequent Southern blot analysis revealed a DNA that was related but not identical to any of the papillomaviruses in this HPV-5 group. The fourth lesion studied a few years earlier contained HPV-5c. The question arises whether a different type of HPV is responsible for development of these tumors in black patients with EV.