It is formed by the abnormal increase and accumulation of melanin particles secreted by melanocytes or melanocytes in the skin. For example, common moles are formed by the accumulation of increased melanocytes into nests or spheres; However, in Ota nevus and freckle nevus, there are many scattered melanocytes, which can present different colors due to different distribution depths. There are many kinds of nevus, the most common ones are localized nevus (divided into borderline nevus, intradermal nevus and mixed nevus according to the depth), in addition to giant nevus (congenital melanocyte nevus with a huge area), halo nevus (skin around melanocyte nevus in hypopigmentation), simple freckles (nevus), freckles (appearing in exposed parts such as face and darkening brown after sun exposure), brown and milk spots (appearing light brown spots at birth). 1. Chemicals in the market are cauterized with strong acid or alkali chemicals, while Dot mole trichloroacetic acid is used in hospitals, which has a good effect on newly emerging and shallow combined moles, and often leads to sunken scars due to excessive cauterization, or raised scars due to scar formation. 2. Electrocautery is effective for superficial combined nevus and deep and prominent compound nevus. Surgery is not easy to control, and it is easy to produce scars. 3. Freeze the mole with liquid nitrogen. Can effectively remove protruding and flat moles. Because depth control is not easy, it often causes injuries, so now dermatology does not need to treat moles. 4. Surgical resection can be done once and for all. If there is a possible malignant mole, pathological examination can be carried out after resection. Excision is a kind of operation, which requires anesthesia and suture, and the wound is difficult to take care of. 5. Laser gasified nevus has no trace after demobilization except some punctate bleeding after laser surgery. It is only suitable for shallow nevus, because the residual melanocytes under the skin will pop up again and again, and it is a bit difficult to keep eyebrows after multiple laser treatments. At present, there are many plastic surgery methods, each with its own advantages and disadvantages. First of all, the doctor should check the state of the mole and make suggestions before making a decision. Electrocauterization: Using the principles of electric heating and high-temperature cauterization, moles caused by cauterization and carbonization are removed. Advantages: simple operation, which can be operated by some beauty salons. Disadvantages: it is difficult to control the degree of burning, and it is easy to leave scars. Indications: nevus with a diameter of 0.3-0.5 cm. Laser Dot mole method: At present, laser can be used to remove moles on the surface, such as ruby laser, chrome laser or dye laser. If it is a large and deep mole, it should be removed by carbon dioxide ultra-pulse laser. Advantages: Laser nevus removal can control the best spot size and depth, and it is not easy to leave scars and infections. Disadvantages: if the mole is too deep, you may still have to play several times. Indications: Most of them can be used, including deep and shallow nevus. Surgical resection: surgical resection of diseased tissue around nevus. Advantages: this method can choose to partially or completely remove the diseased tissue, and different treatment methods can be carried out according to the nature of hydatidiform mole. Disadvantages: it is difficult and takes a lot of time. This method is rarely used in general moles. Indications: large and prominent nevus with a diameter greater than 0.6 cm. Chemical etching method: generally, 50% triazene carbonic acid solution or sodium hydroxide and other alkaline agents are applied to the nevus. Advantages: Triazole carbonic acid solution is not easy to burn the skin and cause scars; Alkaline solution is corrosive and may take effect soon. Disadvantages: triazole carbonic acid solution acts slowly, and the deeper mole may be 10 times; Sodium hydroxide is not easy to control the corrosion depth, and it is easy to cause deep scars. Indications: Nevus with light color and light position. Freezing method: freeze with liquid nitrogen, so that the tissue of pigmented nevus is frozen at high speed, and the cells around pigmented nevus form water sores, and then fall off on their own. Advantages: The depth of the injury is relatively easy to master, usually once, and it is not easy to cause obvious scars. Disadvantages: large and thick moles can only be taken out after repeated freezing, and special instruments must be equipped, and the doctor's skills are also very important. Indications: Flat nevus with a diameter of 0.3-0.5 cm, including freckles.