Actinic keratosis on the forearms

Cumulative skin damage is caused by repeated exposure to the ultraviolet light found in sunshine. Areas with high exposure such as the forearms, face, back of the neck, and scalp (bald individuals) are common sites. Over the years, the genetic material of cells becomes irreparably damaged and may produce lesions like these on the forearms. The lesions, called actinic keratosis, may later become cancerous.