Dermatofibroma is a common, benign skin growth that typically appears as a small, firm bump on the skin. These growths are usually brown or tan and can vary in size. They often develop on the arms or legs and are more common in adults, particularly women. Dermatofibromas are generally harmless and do not require treatment unless they become bothersome or for cosmetic reasons. The exact cause of dermatofibromas is not well understood, but they may arise from minor skin injuries or insect bites. While they are not cancerous, a healthcare professional can confirm the diagnosis through a physical examination or, if necessary, a biopsy.