Dermatofibroma: A common type of benign skin tumor that is small, slow-growing, typically firm, red-to-brown and most often on the legs. Also called a fibrous histiocytoma. They can grow up to about 1 cm (less than a half inch) in diameter. A dermatofibroma consists of a proliferation of scar-like tissue within the deeper layers of the skin (dermis).

The cause of dermatofibromas is unknown. They are usually single but sometimes may be multiple. Simple excision is curative.