Precancerous Skin Conditions
Actinic (Solar) Keratosis. Actinic keratosis (also called solar keratosis) is a skin lesion caused by too much sun exposure. There is some increased risk of skin cancer in patients who have these lesions, but the risk of one specific actinic keratosis turning into cancer is low. The increased risk of cancers may be due to the fact that heavy sun exposure has been linked to both actinic keratosis and nonmelanoma skin cancers.
Actinic keratosis occur after years of sun exposure. They appear mostly on sun-exposed skin, such as the face, neck, back of the hands and forearms, upper chest, and upper back. Men may develop keratosis along the rim of the ear.
Actinic keratosis have the following characteristics:
- Lesions typically occur on the surface of the skin and have a sandpaper-like feel. In fact, they are sometimes more easily felt than seen.
- Most lesions are pink and even flesh-colored. Some are red or brown, scaly, and tender. At times, they can resemble melanomas; even dermatologists may have trouble telling the two apart.
- They can range in size from microscopic to several inches in diameter.
Keratoacanthomas. Keratoacanthomas closely resemble squamous cell cancers, but they are not cancerous. Most of these occur in sun-exposed skin, usually on the hands or face. They are typically skin colored or slightly red when they first develop, but their appearance typically changes:
- In the early stages, keratoacanthomas are smooth, red, and dome shaped.
- Within a few weeks, they can grow rapidly, usually to 1 or 2 centimeters. Some reach the size of a quarter in less than a month and can be disfiguring.
- They eventually stop growing and become crater-like, with a surrounding outer rim of tissue and sometimes a crusty interior.
Most will get better on their own within 1 year, but they almost always scar after healing. Also about 25% develop into squamous cell cancers, most frequently in older people and in sun-exposed areas. Removal by surgery (sometimes by radiation) is recommended. They may also be treated with 5-fluorouracil, either as a cream or injections.
Review Date: 07/04/2010
Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.