Hypertrophic actinic keratosis on the forehead of an 83 year old patient. This is a precancerous skin growth caused by sun damage. The damage occurs years before the lesion appears. Actinic, or solar, keratoses are mostly found on areas of skin that are exposed to the sun most often, including the backs of hands and the face. In the hypertrophic form the lesion develops into a scaly plaque. It is important to remove the lesions as they can develop into skin cancer. They may be removed by scraping, freezing with liquid nitrogen, or surgery. New keratoses often appear at or near the site of a previous keratosis, therefore regular check-ups are needed.