Generally, the so-called nevus refers to the black nevus, which is scientifically called melanocyte nevus. A nevus is a collection of nevus cells, which can grow in all parts of the body. Melanocytes exist in normal skin, and they are evenly distributed throughout the body. The function of melanocytes is to produce melanin and spread it to almost every epidermal cell. Epidermal cells themselves do not produce melanin, but there may be one melanocyte in every 20 ~ 30 epidermal cells, which will produce melanin and pass it on to nearby epidermal cells. Everyone has a mole more or less. Most moles are acquired and appear one by one after puberty. The number and size of moles are related to the risk of malignant melanoma. According to statistics, people with more than 100 moles are 3.4 times more likely to develop malignant melanoma than those with less than 25 moles, and if there are 50 moles larger than 2 mm, the probability of developing malignant melanoma is 4 ~ 54 times that of the general population. What kind of mole should be removed? In addition to aesthetic factors, in order to avoid becoming malignant melanoma, the following moles should be removed: 1. Moles that will be stimulated by long-term friction, such as those on bras and waist. 2. Nevus with atypical changes. Nevus with atypical appearance may become malignant, such as very dark nevus, uneven (mottled) pigment, uneven or irregular edge, unclear boundary, asymmetric left and right, and statistically larger than 5 mm in diameter. 3. A mole will change suddenly and rapidly. If the mole of the whole body changes at the same time because of the change of the black door, there is no doubt about it. If a single mole changes suddenly and rapidly, it is worth noting. 4. moles that grow in special parts. For example, moles growing on limbs (hands and feet) must be observed, because moles in these places are more likely to become malignant melanoma than moles in other places. 5. Mucosal nevus. A mole is the part of the oral mucosa, conjunctiva, vagina and foreskin that is turned out. 6. Nail groove nevus. The nail groove is connected with the skin under the nail, which may grow under the nail and be blocked by the nail, so it is not easy to see the change, and it grows at the end and is more likely to become malignant in the future. 7. Some moles are high-risk moles. A mole that can be seen when a baby is born is called a congenital mole. There are not many congenital moles. Generally speaking, the bigger the mole, the greater the chance of malignant transformation in the future. Therefore, it is recommended to remove it as soon as possible. Some people have the physique of swollen crab feet, and scar tissue will proliferate abnormally, resulting in hypertrophic scars. Crab foot swelling is common in earlobe, shoulder, upper arm, chest and back, but not in face. If people with this physique want to get rid of moles for beauty, they should first inform the doctor of their physique so as not to get rid of moles for big scars. Dangerous malignant melanoma benign nevus becomes malignant melanoma: protuberance, extreme melanin, itching, pain, bleeding, ulcer. Skin cancer mainly includes three types: malignant melanoma, basal cell carcinoma and squamous cell carcinoma. Malignant melanoma accounts for 4% of all skin cancers, but it leads to nearly 80% of skin cancer mortality, which is one of the worst prognosis of all cancers. 10 ~ 15% patients with malignant melanoma have a family genetic history. The incidence of malignant melanoma in yellow race is lower than that in white race. It is pointed out that 70 ~ 80% of malignant melanoma in China is acromegaly nevus, which is characterized by its predilection in palm, sole and other parts that may not be exposed to sunlight, as well as in body mucosa. Malignant melanoma of acromegaly often invades the skin basement membrane vertically and invades subcutaneous blood vessels or lymphatic vessels when the tumor is still very young, and then metastasizes. Once metastasized, the prognosis is extremely poor, and the three-year survival rate is only about 10%. Nevus may change, some changes are warning signals, they will become malignant, and some changes are benign. Whether the nevus is malignant or not can be determined by biopsy. Once the nevus becomes malignant melanoma, it will deteriorate rapidly. How to remove moles? The way to remove moles usually depends on the type, size and location of moles. Generally speaking, more than 3 mm must be removed. 1. If it is suspected to be malignant, it should be removed, and biopsy should be done, so the laser may not be clean. Compound nevus and dermal nevus are too deep and protruding. If they want to be cleared, they should be cleared. Larger nevus should be sutured after excision, and even skin grafting (transferring a piece of skin from other places) and skin flap transfer (taking the meat next to it) are needed. 2. Laser laser is a therapeutic method to convert electric energy into light, which is suitable for small and shallow moles, such as flat-seam moles. 3. High-frequency electrocautery destroys cells with heat energy. 4. Liquid nitrogen freezing is destroyed at the low temperature of-196 degrees Celsius, but it is rarely used. 5. The disadvantage of chemical cauterization is that it is difficult to control the depth and range of cauterization. When burned, there will be concave holes, some of which are deep, so the medical profession does not use this method, but some beauty salons and night market stalls in Dot mole like to use it. Ou said that almost all moles can be removed, but if they are not handled properly, most will leave obvious scars. It is difficult to remove moles on eyelids and nose; Eyelids are difficult to sew, nasal nevus is difficult to repair, and skin grafting or skin flap transfer is needed; It is easier to do nevus removal surgery with decree lines because there are many surrounding tissues. Precautions before and after operation: Do not apply any maintenance or cosmetics before nevus resection and laser surgery. These operations require anesthesia. The laser uses epidermal anesthesia and the resection uses injection anesthesia, both of which require consent. After laser surgery, we should do a good job of sun protection, and apply antibiotic ointment or artificial skin according to the doctor's advice before the wound scabs off to ensure the best effect. Apply beauty patch 3 ~ 6 months after stitches are removed. Who should I ask for help in removing moles? Laser, plastic surgery and dermatology can all be used, and the operation methods are the same. Some patients go directly for plastic surgery. Dermatologists in big hospitals can do skin biopsy and interpret the results themselves. It is no problem to use laser to remove moles for cosmetic purposes. But large-scale excision, even skin grafting, or facial beauty and function are more suitable for reference plastic surgery. Ordinary people should pay attention to observe whether the moles on their bodies have changed. If they feel suspicious, they should see a doctor as soon as possible.