An actinic keratosis (ak-TIN-ik ker-uh-TOE-sis) is a rough, scaly patch on your skin that develops from years of exposure to the sun. It's most commonly found on your face, lips, ears, back of your hands, forearms, scalp or neck. Also known as a solar keratosis, an actinic keratosis enlarges slowly and usually causes no signs or symptoms other than a patch or small spot on your skin. These patches take years to develop, usually first appearing in people over 40. A small percentage of actinic keratosis lesions can eventually become skin cancer. You can reduce your risk of actinic keratoses by minimizing your sun exposure and protecting your skin from ultraviolet (UV) rays.