Nonmelanoma skin cancer.

Nonmelanoma skin cancer is the most common cancer in the United States, and its incidence is increasing dramatically. Although mostly caused by sun exposure, less common causes are also discussed. Several types of basal cell carcinomas are described, as well as squamous cell carcinoma. While these carcinomas rarely cause death, they can be locally destructive, and removal can cause significant disfigurement and functional impairment. The value of early detection is emphasized.