Nonmelanoma skin cancer.

Nonmelanoma skin cancers encompass a vast array of malignancies: adventitial, vascular, neuroendocrine, hematologic, adnexal, and epithelial. The skin is also a major site for metastasis of internal disease. With an understanding of the frequency of presentation, clinical distribution, and appearance, the clinician is able to provide an accurate diagnosis for most lesions. Because there are so many nonmelanoma skin cancers, the focus here is on those with a high frequency or significant morbidity. The treatment of nonmelanoma skin cancer is constantly evolving; therefore, emphasis is on diagnosis.