Viral-associated nonmelanoma skin cancers: a review

Nonmelanoma skin cancers are the most common malignancies in the United States, with over 1.3 million patients diagnosed yearly. Several types of nonmelanoma skin cancer and precancerous lesions have an associated viral pathogenesis, including epidermodysplasia verruciformis, verrucous carcinoma, bowenoid papulosis, Kaposi sarcoma, squamous cell carcinoma, and, most recently, Merkel cell carcinoma. It is now widely accepted that high-risk human papillomaviruses (HPVs) play a key role in pathogenesis of cervical and anogenital cancer. Currently, 108 types of HPV have been discovered. They can be divided into genera including alpha, beta, and gamma HPVs, which comprise the majority of cutaneous HPVs. The relationship between viruses and cancer is a popular focus of research in an era of AIDS and organ transplantation, where immunosuppression is not uncommon. The incidence of viral-related malignancies in these populations is increasing. Because of the widespread nature of these cutaneous malignancies, an evaluation of these conditions is valuable. This review of the literature will focus on the histologic aspects of viral-associated skin malignancies, as well as the epidemiology, etiology, and clinical aspects of these diseases.