Dermatofibromas are hard solitary slow-growing papules (rounded bumps) that may appear in a variety of colours, usually brownish to tan. In addition, they are often elevated or pedunculated. Although typical dermatofibromas cause little or no discomfort, itching and tenderness can occur. 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 it may be confused with a variety of subcutaneous tumours.
Dermatofibroma can be found anywhere on the body but most often they are found on the legs and arms.
Deep penetrating dermatofibroma may be difficult to distinguish, even histologically, from rare malignant fibrohistocytic tumours like dermatofibrosarcoma protuberans.
Dermatofibromas occur most often in women; the male to female ratio is about 1:4. The age group in which the nodule occurs is twenty to forty-five years.
It is associated with the dimple sign; by applying lateral pressure, there is a central depression of the dermatofibroma.
^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.