Dermatofibromas are small, noncancerous (benign) skin growths that can develop anywhere on the body but most often appear on the lower legs, upper arms or upper back. These nodules are common in adults but are rare in children. They can be pink, gray, red or brown in color and may change color over the years. They are firm and often feel like a stone under the skin. When pinched from the sides, the top of the growth may dimple inward.
Dermatofibromas are usually painless, but some people experience tenderness or itching. Most often, a single nodule develops, but some people can develop many dermatofibromas. They rarely grow larger than a half-inch in diameter. The cause of dermatofibromas is unknown.