Benign fibrous histiocytomas (also known as Dermal dendrocytoma,Dermatofibroma,Fibrous dermatofibroma,Fibrous histiocytoma,:668Fibroma simplex,Nodular subepidermal fibrosis, and Sclerosing hemangioma) are benign skin growths.
Dermatofibromas are hard solitary slow-growing papules (rounded bumps) that may appear in a variety of colours, usually brownish to tan; they are often elevated or pedunculated. A dermatofibroma is associated with the dimple sign; by applying lateral pressure, there is a central depression of the dermatofibroma. Although typical dermatofibromas cause little or no discomfort, itching and tenderness can occur. Dermatofibromas can be found anywhere on the body, but most often they are found on the legs and arms. They occur most often in women; the male to female ratio is about 1:4. The age group in which they most commonly occur is twenty to forty-five years.
Some physicians and researchers believe dermatofibromas form as a reaction to previous injuries such as insect bites or thorn pricks. They are composed of disordered collagen laid down by fibroblasts. Dermatofibromas are classed as benign skin lesions, meaning that they are completely harmless, though they may be confused with a variety of subcutaneous tumours. Deep penetrating dermatofibromas may be difficult to distinguish, even histologically, from rare malignant fibrohistocytic tumours like dermatofibrosarcoma protuberans.
^Kim HJ, Lee JY, Kim SH et al. (August 2007). "Stromelysin-3 expression in the differential diagnosis of dermatofibroma and dermatofibrosarcoma protuberans: comparison with factor XIIIa and CD34". Br. J. Dermatol.157 (2): 319–24. doi:10.1111/j.1365-2133.2007.08033.x. PMID17596171.