Pigmented nevi are common skin lesions. Most pigmented nevi are of benign type, but a very small percentage of pigmented nevi may transform into melanoma under certain factors. Melanoma is a malignant tumor with a fairly high degree of malignancy, also known as malignant melanoma. Most of them originate from the skin and can metastasize at an early stage and spread rapidly, with metastatic sites mostly found in the lung, liver, bone, brain and other organs, and some patients die several months to years after diagnosis. In the movie “Do Not Disturb 2”, Li Xiangshan, played by Sun Honglei, chose to commit suicide because a mole on the back of his foot turned into a “terminal” melanoma, and many viewers remember this episode vividly. The 5-year cure rate for very early superficial melanoma is still good, so the cure depends on early diagnosis and treatment. Melanoma is highly prevalent in Caucasians, and the incidence in yellow people is much lower than that in Caucasians, but it does not mean that Chinese people can take this disease lightly, because: 1. the total population of China is large and is entering an aging society, with the increase of life expectancy per capita, the incidence of malignant transformation of pigmented nevi also rises, and the total number of patients with the disease is not small; 2. Most people ignore the sensory changes of pigmented nevi because of indifferent cognition of risk factors. Patients often have two purposes in seeking treatment for skin pigmented nevi: 1) cosmetic needs; 2) preventive excision of lesions to prevent malignant changes. So, which pigmented nevi require active treatment? For the treatment of pigmented nevi, clinicians generally recommend the following: 1. Junctional nevi, especially the junctional nevi of the extremity (palmoplantar) and the junctional nevi of the friction area, are dangerous and should be actively treated; 2. Pigmented nevi with diameter larger than 0.6cm, uneven color, unclear boundary and irregular shape should be actively treated; 3. Pigmented nevi that change rapidly within a short period of time, or even break out and have obvious symptoms, should be treated early. diagnosis and treatment. Some birthmark moles that tend to be larger in size should also be given special attention. e stands for elevation, and some moles have cells that are present at birth and will increase in size and bulge as the body grows. Some nevus cells may differentiate slowly between the ages of 10 and 30, so it is normal for nevi to grow one after another. Patients can monitor the gradual change of nevus foci by taking pictures with a digital camera on a regular basis. This can be done by comparing the photos with the marker ruler placed next to the nevus foci, so that the process of small changes in the foci can be observed dynamically on follow-up; special care should be taken for fast-growing and fast-rising nevi. If patients find unusual changes in their skin moles, they should not ignore them or use wrong methods such as scratching, drug erosion, scraping or cutting that may induce malignant changes or accelerate melanoma metastasis, but go to regular medical institutions immediately. At present, most conventional treatments for pigmented nevi are laser or surgical excision treatments. Laser treatment of pigmented nevus is easy to perform, with little trauma and quick recovery. However, laser treatment of pigmented nevus also has defects. The reasons are: 1. Most pigmented nevi involve the dermis, so the treatment must break through the dermal papilla layer, which may leave scar after laser treatment, and the cosmetic effect is not satisfactory; 2. Such stimulation may increase the chance of malignant transformation of pigmented nevus. 4. The lesion cannot be examined pathologically. Therefore, surgical excision is recommended for cases where the nature of the nevus is doubtful. Surgical excision can remove the pigmented nevus, and the postoperative specimen can be sent for pathological examination to clarify the diagnosis. For nevus on the face and other exposed areas, it is recommended to apply the principles and methods of plastic surgery to treat the nevus to take into account the cosmetic effect. Reduction sutures facilitate wound healing and reduce scar formation; intradermal suture technique can avoid the formation of centipede foot-like scars after conventional suturing. In the case of giant nevus and other lesions with a large wound area that cannot be pulled together and sutured, traumatic skin grafting or flaps can also be used to repair the wound. In the case of malignant melanoma confirmed by pathological examination of the lesion after surgery, a series of treatments such as extended radical surgery must be performed in a timely manner to save lives according to the distance of the cut edge of the lesion and the thickness of the lesion.