Keratoacanthomas are round, firm, usually flesh-colored growths that have a central crater that is scaly or crusted.

Keratoacanthomas appear most commonly on the face, forearm, and back of the hand and grow quickly. In 1 or 2 months, they can grow into lumps up to 1 inch wide, after which they begin to shrink. They usually disappear within 6 months, often leaving a scar. They may be caused by a virus, but doctors are not sure.

Keratoacanthomas closely resemble squamous cell carcinoma, a type of skin cancer (see Skin Cancers: Squamous Cell Carcinoma), and some doctors believe that they may actually be an unusual form of squamous cell carcinoma. Therefore, doctors often perform a biopsy, in which a piece of skin is removed and examined under a microscope. Keratoacanthomas can be cut out or scraped (curetted). Alternatively, they can be treated with injections of corticosteroids or fluorouracil.

Last full review/revision February 2003