Acne is a kind of skin disease popular among teenagers, which is divided into manifestations of acne, papules, pustules, nodular cysts and so on. 1. Acne: small dots close to skin color are distributed on the face, follicular openings can be seen on the surface, and strips or rice grains of beige, translucent keratin plugs will appear after squeezing. 2. Inflammatory papules: the lesions are mainly inflammatory papules, densely distributed, usually light red or dark red. 3. Pustules: on the basis of inflammatory papules, white pustules appear at the top of the papules. 4. Nodules and cysts: the inflammation is more severe, forming subcutaneous nodules and cysts, which are painful to touch. There is sticky pus inside, often leaving scars after treatment. Teenagers with acne should be under the guidance of a professional dermatologist to use medication, do not squeeze with your hands to avoid adverse complications.