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What is a dermatofibroma?
Dermatofibromas are the second most common fibrous lesion of the skin. The most common is a skin tag. —Dr. Mollie MacCormack
A dermatofibroma is a harmless, non-cancerous, overgrowth of skin cells called fibroblasts. It may also be called a cutaneous fibrous histiocytoma.
Dermatofibromas are small, usually painless, raised bumps. They can be flesh colored, tan, brown, or reddish-pink. They grow most commonly on the lower legs and they affect women more often than men.
They may appear after a minor skin trauma, like a cut or bug bite. Usually, they develop over time, growing slowly until they reach less than 1 cm (about ¼ inch) in size.
On rare occasions, larger lesions do occur, but dermatofibromas larger than 1 cm should be evaluated by a doctor.
While dermatofibromas are not cancerous, it’s a good idea to get any new skin growth checked by your doctor.
A dermatofibroma will not go away on its own, but it can be removed by a doctor if you wish.
Most common symptoms
Most often, patients notice a new, small bump on their leg. But it can be on other areas of the body. —Dr. MacCormack
Dermatofibromas are raised, firm bumps that are usually less than 1 cm in diameter, but on occasion can be larger.
They can be pinkish in light-skinned individuals, or tan or brown in people with darker skin. And are usually painless, though itching, irritation, or bleeding may occur, especially if they get frequently brushed by clothing or zippers or nicked while shaving.
A dermatofibroma may form a small dimple in the middle when you pinch it. This is called the “dimple sign.”
- Firm raised papule
- 5mm to 1cm diameter
- Pink, tan, or brown
- Painless, but may itch or feel irritating
- May have a dimple sign when squeezed
Why do I get dermatofibromas?
There is no clear reason why some people develop a dermatofibroma. They occur when skin cells called fibroblasts overgrow, forming a bump. But the reasons why this occurs aren't entirely clear.
One theory is that a dermatofibroma is a “reactive growth.” This means it occurs as a response to something, which could be mild skin trauma like an insect bite or cut.
Women are more likely than men to develop them.
People with a weakened immune system, such as those with other illnesses like lupus, may be more likely to develop this growth.
If you detect a new bump on your skin that doesn’t go away, it is always important to have it checked out by a doctor to make sure it’s not a skin cancer.
A doctor can confirm the diagnosis by using a special magnifying glass called a dermascope. They may also take a tiny tissue sample, called a biopsy, to examine under a microscope.
Once it’s diagnosed, you can discuss your treatment options with your doctor. You can leave it alone, or get it removed.
Treatment of dermatofibromas
Tell your doctor if the lesion is large, growing rapidly, or has ill-defined margins. It could be dermatofibrosarcoma protuberans, a form of skin cancer. —Dr. MacCormack
A dermatofibroma does not require treatment. Some people find it irritating or unattractive and want to get it removed. A dermatologist can usually perform this procedure in-office under local anesthesia.
Your dermatologist will use a local anesthesia to numb the area so you won’t feel it. Using a scalpel, an oval-shaped incision will be made around the lesion so that it is removed in its entirety.
If a dermatofibroma is not removed completely (for example if a shave removal clears the top of the lesion only) it will often grow back. Once the dermatofibroma is removed, the doctor will close the wound with stitches.
Your doctor will give you post-procedure directions, which are important to follow to reduce the risk of abnormal scarring. This includes keeping the wound clean and dry, and moisturized with vaseline.
You should follow up with your doctor for removal of stitches if necessary.
William C. Fix is a resident physician specializing in dermatology at the Albert Einstein College of Medicine and Montefiore Medical Center in New York. He graduated from Brown University with a BA in Economics in 2012 and obtained his MD from the University of Pennsylvania Perelman School of Medicine in 2019. William has received grants from the American Society for Dermatologic Surgery, The National Institutes of Health and the Alex’s Lemonade Stand Foundation for oncology research, and was selected for the University of Pennsylvania’s Dermatology Oncology Center (PennDOC) Research Fellowship in Dermatology & Dermatologic Surgery. William’s interests include general and procedural dermatology, cutaneous oncology, technology, and quality improvement.