Actinic keratosis (AK) is a crusty, scaly growth that appears on the skin and is caused by damage from exposure to ultraviolet (UV) radiation. AK is considered a precancer because when it goes untreated, it can potentially develop into skin cancer. AK appears on skin that has been frequently exposed to the sun or to fake sources of UV light, like tanning machines. In rare cases, a large amount of exposure to X-rays can cause them. They appear on sun-exposed areas of the body, including:
- the face
- bald scalp
- ears
- shoulders
- neck
- the back of the hands
- forearms
