Actinic keratosis: Common skin spots from sun exposure

Actinic keratosis results from an overgrowth of keratin, a protein in the skin. It’s caused by exposure to ultraviolet (UV) rays, typically from the sun. It affects about 14% of people and, in some cases, can develop into squamous cell carcinoma, a type of skin cancer. This progression to cancer is somewhat rare but is more likely when actinic keratoses are left untreated.

Actinic keratoses may appear as rough, scaly patches or crusts on the top layer of the skin. The lesions may range in color, including white, pink, red, gray and flesh-colored, and are darker on Black and brown skin tones. They’re usually 1 inch or less in size and are found primarily on areas exposed to the sun, including the face, lips, ears, back of the hands, forearms, scalp and neck.

There may be a single lesion but often there are several. Actinic keratoses take years to develop and usually first appear in older adults. The patches grow slowly and usually are not itchy or painful.