Recognition and management of unusual cutaneous tumors

Basal cell carcinoma, squamous cell carcinoma, and melanoma are sometimes referred to as the big three because they are the most commonly encountered cutaneous malignancies. There are several other important, although less commonly seen, cutaneous carcinomas that must be remembered to provide a comprehensive and accurate differential diagnosis of cutaneous neoplasms. These unusual cutaneous cancers often mimic a basal cell carcinoma or squamous cell carcinoma. This article discusses several of these unusual tumors that all dermatologists encounter, including dermatofibrosarcoma protuberans, atypical fibroxanthoma, malignant fibrous histiocytoma, angiosarcoma, extramammary Paget's disease, Merkel's cell carcinoma, leiomyosarcoma, and sebaceous carcinoma.