A dermatofibroma is an overgrowth of the tissue in the dermis layer of the skin. It is a small, firm bump on the skin. They are harmless and will not turn into skin cancer.

Layers of the Skin
Cut-away of the Skin
In dermatofibroma, the overgrowth occurs in dermis layer of the skin.
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The cause is not known. Sometimes they happen after a minor injury to the skin, such as an insect bite or a prick from a thorn.

Risk Factors

They are more common in adults and happen most often in women.


They are most common on the lower legs, but can also appear on the upper arms. They may be:

  • Brown, purple, yellow, red, or pink in color, sometimes with a darker rim
  • Smaller than 1 centimeter
  • Firm
  • Raised from the skin


Your doctor will ask about your symptoms and health history. A physical exam will be done. It will focus on the growth. This may be enough to make the diagnosis.

A growth that cannot be diagnosed may be surgically removed. It will be examined in a lab.


These growths do not go away with time. They also do not need to be treated unless they cause discomfort or are unsightly.

Surgery may be done to remove the growth. This often leaves a scar.

Liquid nitrogen can also be used to freeze the growth and flatten it. This often leaves a white mark. The growth may also come back.


There are no methods to prevent these growths. The cause is not known.

Revision Information

  • Reviewer: EBSCO Medical Review Board James P. Cornell, MD
  • Review Date: 09/2019 -
  • Update Date: 11/21/2019 -