Keratoacanthomas are round, firm, usually flesh-colored growths that have a central crater that is scaly or crusted.
Keratoacanthomas appear most commonly on sun-exposed areas, the face, forearms, and back of the hands and grow quickly. In 1 or 2 months, they can grow into lumps up to 1 inch (about 2.5 centimeters) wide. They may spontaneously disappear within a few months, often leaving a scar. The cause is unknown.
Most doctors consider keratoacanthomas to be a form of squamous cell carcinoma, a type of skin cancer (see Squamous Cell Carcinoma). Therefore, doctors often do a biopsy, in which a piece of skin is removed and examined under a microscope, to rule out cancer. Keratoacanthomas are usually cut out or scraped (curetted) or injected with methotrexate or fluorouracil.
Last full review/revision July 2013 by Gregory L. Wells, MD