Originally published by Harvard Health.
What Is It?
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.
Dermatofibromas usually develop slowly. These small, hard, raised skin growths:
- Usually appear on the lower legs, but may appear on the arms or trunk
- May be red, pink, purplish, gray or brown and may change color over time
- May be as small as a BB pellet but rarely grow larger than a fingernail
- Are often painless but may be tender, painful or itchy
- Usually dimple inward when pinched
Most often, a doctor can diagnose a dermatofibroma by examining the nodule. If the growth does not look like a typical dermatofibroma, if a bleeding sore appears on its surface or if the physician wants to be certain of the diagnosis, he or she will do a biopsy. A biopsy removes either part or all of the nodule for examination under a microscope.
Dermatofibromas do not go away on their own. Unless they are removed, the nodules remain for life.
Because no one knows what causes dermatofibromas, there is no way to prevent them.
Dermatofibromas rarely require treatment. Some people may prefer to have their dermatofibromas removed if the growth is unsightly, is in an inconvenient location (such as in a place that repeatedly becomes nicked while shaving or is irritated by clothing), or is painful or itchy.
Because a dermatofibroma grows deep, removal requires excising it below the surface level of the skin. This process usually leaves a noticeable scar. Alternatively, the nodule may be flattened to the surface of the skin by shaving the top off with a surgical knife, but this removes only the top layers of the dermatofibroma, leaving the deeper layers so that the nodule may grow back again after several years.
Very rarely, a certain skin cancer that initially resembles a dermatofibroma can spread. This skin cancer has a long name called a dermatofibrosarcoma protuberans (DFSP).
When To Call a Professional
See a doctor to get an accurate diagnosis of any new skin growth, especially one that is dark brown or black or changes color, size or shape. See a doctor immediately if the growth bleeds, grows quickly or becomes painful.
Dermatofibromas are noncancerous growths and they do not become cancerous.
American Academy of Dermatology
P.O. Box 4014
Schaumburg, IL 60168-4014