Actinic keratosis (AKs) is known as the early beginnings of skin cancer. This most common lesion of the outermost layer of the skin (epidermis) is caused by long-term exposure to sunlight (specifically to ultraviolet wavelengths). AKs are most likely to appear after age 40-50, and years of chronic exposure to the sun. However, in geographic areas with year-round high-intensity sunlight (e.g., Florida, southern California). AKs are now found in persons as young as the teens and twenties. The incidence of AKs is over 50 percent in older, fair-skinned persons in hot, sunny geographic areas.