The lesions may appear as horn-like protrusions, which is one of the main symptoms of actinic keratosis. Actinic keratosis is an occupational disease that is triggered by sunlight, ultraviolet light, radioactive heat, and asphalt or coal and its refining. The lesions are mostly found on sun-exposed areas of middle-aged men and above, such as the face, auricles, and the back of the hands. The main manifestation is a rough surface with keratinized scales. When the scales are removed, the underlying basal surface is seen to be red, bumpy and papillate. Treatment is usually topical and surgical. There is a 20% chance of secondary squamous carcinoma. Prognosis 20% of the cases may develop squamous carcinoma. It is generally accepted that squamous carcinoma with actinic keratosis is non-aggressive, rarely metastasizes, and has a good prognosis. Prevention The occurrence of this disease is closely related to sunlight exposure, especially the medium-wave ultraviolet radiation (spectrum 280-320nm), so those who work outdoors or go out frequently should rub sunscreen on sun-exposed skin, such as 5% titanium dioxide ointment, 5% paraben cream and sunscreen. You can also wear an umbrella or sun hat when you go out.