Actinic keratosis (AK) is a lesion that forms on sun-damaged skin. The lesions are small scaly patches on parts of the body, such as the face, ears, bald scalp, arms, and hands, which have been chronically exposed to the sun.
AK is a precancerous condition that affects only the top layer of skin (the epidermis). Ultraviolet (UV) rays from the sun damage the skin and, if left untreated, 10% of AK can turn into a form of skin cancer called squamous cell carcinoma (SCC). When they are found early, AKs are highly treatable.
AK is more common in people with fair skin. It is found in 15% of people in North America and Europe. Australia has the highest rate of AK in the world.