Dermatofibroma: How to Recognize This Common Skin Lesion (With Images)
Key takeaways:
Dermatofibromas are small, noncancerous skin growths that appear as smooth, firm bumps usually on the arms or legs.
Depending on your skin tone, dermatofibromas can be pink, purple, brown, or even black.
Dermatofibromas don’t usually cause symptoms, and treatment isn’t necessary.
Treatment options for people who want it include surgery, lasers, and cryotherapy.
Table of contents
If you have a “mosquito bite” on your leg that won’t go away, chances are that it’s not actually a bite but rather a dermatofibroma. Dermatofibromas are very common, noncancerous skin growths that usually develop on the arms and legs, and don’t cause any symptoms.
If you know what to look for, dermatofibromas are usually pretty easy to spot. Here, we’ll show you what these lesions look like (with pictures), review what causes them, and discuss what you can do about them if they bother you.
What is a dermatofibroma?
A dermatofibroma is a small, benign (noncancerous) skin lesion that usually appears on the legs or arms. They can happen at any age but are more common in women and in people between the ages of 20 and 50 years. Some physical features of dermatofibromas include:
Round, firm, smooth growths that can either be raised or sunken in
Pink, purple, brown, or even black lesions depending on a person’s skin tone
Lesions less than 1 cm in size (smaller than a dime) but sometimes can grow larger
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Most dermatofibromas don’t cause any symptoms. But sometimes they can be itchy or even tender. Healthcare professionals can usually diagnose a dermatofibroma based on what it looks like. But, sometimes a skin biopsy — a surgical procedure to remove and examine a small piece of the lesion — is needed to confirm the diagnosis.
Pictures of dermatofibromas
Here are some pictures of dermatofibromas on different skin tones and different body parts.
What causes dermatofibromas?
Scientists aren’t exactly sure on what causes dermatofibromas. One possibility is that they develop in response to a skin injury (similar to a scar). In fact, about 1 in 5 dermatofibromas develop after some type of trauma, like an insect bite or other minor skin injury.
Treatment and removal of dermatofibromas
Most dermatofibromas don’t go away on their own. Since they don’t usually cause any symptoms or get any bigger, many people opt to leave them alone. Dermatofibromas don’t carry a risk of cancer, so it’s not necessary to remove them.
If a dermatofibroma is causing symptoms or you don’t like the way it looks, there are some treatment options. Keep in mind that the treatment may sometimes leave a more noticeable scar than the dermatofibroma itself.
Surgical removal: The skin is numbed and the lesion is removed with a surgical blade. Stitches may be required depending on the type of removal.
Cryotherapy: Liquid nitrogen spray freezes the top of the lesion. This may flatten out the lesion but doesn’t completely remove it.
Laser therapy: Different lasers can help minimize the appearance of a dermatofibroma.
When to get care for a dermatofibroma
Most dermatofibromas don’t require any medical attention. However, here are some situations when it’s a good idea to have it checked by a healthcare professional:
Your dermatofibroma is causing you symptoms, like itching or pain.
You’re not sure whether it’s a dermatofibroma or something else.
Your dermatofibroma is changing shape or color.
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Frequently asked questions
The pinch test (also called the dimple sign) is a simple test that healthcare professionals use to help differentiate a dermatofibroma from other skin growths.
The test is performed by pinching together the sides of the skin lesion with your thumb and finger. If the lesion dimples or indents, it’s likely a dermatofibroma. But this test isn’t a guarantee. If you have an unknown skin growth, it’s best to see a healthcare professional to get the right diagnosis.
Dermatofibromas are usually pretty small, round, and uniform in color. They also don’t usually grow in size and never turn into cancer. A nodular melanoma, however, is a serious type of skin cancer that has different features from a dermatofibroma. These include:
Irregular borders
Several different colors (like brown, black, and pink) within the lesion
Changing shape or growing in size
Sometimes it’s hard to tell these two lesions apart. That’s why it’s important to get it checked out by a healthcare professional as soon as possible if you have a new skin growth and aren’t sure what it is.
No. Dermatofibromas are noncancerous, and they don’t turn into cancer.
The bottom line
Dermatofibromas are common, noncancerous skin growths that usually appear on the arms and legs. They appear as round, smooth, firm skin bumps, and can be pink, purple, brown, or black. Most dermatofibromas won’t go away on their own, but since they don’t usually cause any symptoms, there’s no need to have it treated or removed. But if a dermatofibroma is cosmetically bothersome or it’s causing symptoms (like itching or pain) they can be treated with surgery, cryotherapy, or laser treatment.
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Images used with permission from VisualDx (www.visualdx.com).
References
American Osteopathic College of Dermatology. (n.d.). Dermatofibroma.
Myers, D. J., et al. (2024). Dermatofibroma. StatPearls.
Oakley, A. (2020). Dermatofibroma. DermNet.
ScienceDirect. (n.d.). Dermatofibroma.
Wang, S. Q., et al. (2006). Treatment of dermatofibroma with a 600 nm pulsed dye laser. Dermatologic Surgery.
