Dermatofibromas are small, rounded noncancerous growths on the skin. The skin has different layers, including the subcutaneous fat cells, dermis, and epidermis. When certain cells inside the second layer of skin (the dermis) overgrow, dermatofibromas can develop.

Dermatofibromas are benign (noncancerous) and harmless in this regard. It’s considered to be a common tumor in the skin that may occur in multiples for some people.

Dermatofibromas are caused by an overgrowth of a mixture of different cell types in the dermis layer of the skin. The reasons why this overgrowth occurs aren’t known.

The growths often develop after some type of small trauma to the skin, including a puncture from a splinter or bug bite.

In addition to minor skin injuries being a risk for dermatofibroma formation, age is a risk factor. Dermatofibromas occur more commonly in adults who are 20 to 49 years of age.

These benign tumors also tend to be more common in women than men.

Those with a suppressed immune system may be at a higher risk for dermatofibromas to form.

Apart from the bumps on the skin, dermatofibromas rarely cause additional symptoms. The growths can range in color from pink to reddish to brown.

They are usually between 7 and 10 millimeters in diameter, although they can be smaller or larger than this range.

Dermatofibromas are also usually firm to the touch. They can also be mildly sensitive to the touch, although most don’t cause symptoms.

The growths can occur anywhere on the body but appear more often on exposed areas, such as the legs and arms.

A diagnosis is usually made during a physical exam. A trained dermatologist can usually identify a growth through a visual examination, which may include dermatoscopy.

Additional testing can include a skin biopsy to rule out other conditions, such as skin cancer.

Typically, dermatofibromas are chronic and don’t spontaneously resolve on their own. Because they are harmless, treatment is usually solely for cosmetic reasons.

Treatment options for dermatofibromas include:

  • freezing (with liquid nitrogen)
  • localized corticosteroid injection
  • laser therapy
  • shaving the top to flatten the growth

These therapies may not be completely successful at removing a dermatofibroma because the tissue may reaccumulate within the lesion until it returns to its size before therapy.

A dermatofibroma can be completely removed with a wide surgical excision, but there is also a high likelihood of scar formation that may be considered more unsightly than the dermatofibroma itself.

Never attempt removal of a growth at home. This can lead to infection, scarring, and excess bleeding.

Since the growths are almost always harmless, dermatofibromas don’t negatively affect a person’s health. Removal methods, such as freezing and excision, have varying degrees of success. In many cases, these growths can grow back.

Researchers don’t currently know exactly why the dermatofibromas occur in some people.

Because the cause is unknown, there is no sure way to prevent dermatofibromas from developing.