Many people come to our clinic to ask questions about moles: suddenly they find many moles on their body after sleeping; recently they find that their original moles have become bigger and thicker; let’s see if my moles are malignant; moles on the face affect the beauty, how to remove them without leaving traces …… In fact, moles exist more or less on everyone’s body, usually increasing in number with age, and they vary in size, shape and color. Medically speaking, nevus is a common benign skin tumor caused by the increase of melanocytes in the epidermis and dermis. According to the time of appearance of nevus, it can be divided into congenital melanocytic nevus and acquired melanocytic nevus. According to the distribution of nevus cells, it can be divided into junctional nevus, mixed nevus and intradermal nevus. Generally speaking, moles with smooth and hairless surface and dark color may be junctional nevi, those with hairy surface and mild elevation are mostly mixed nevi, and those with hemispherical shape or with tip are more likely to be intradermal nevi. Which moles need to be alerted to the possibility of melanoma? We should pay attention to the following situations: 1) when a mole suddenly becomes larger within a short period of time; 2) when a mole becomes irregular in shape, uneven in color, and blurred at the edges within a short period of time; 3) when a mole shows continuous itching, pain, surface rupture or bleeding, and unevenness. If the above situation occurs, you should go to the dermatology department of the regular hospital for consultation in time. At present, the treatment of moles mainly includes physical therapy and surgical treatment, and physical therapy mainly includes laser and freezing. Laser treatment is through high temperature vaporization or selective photothermal principle, which acts on melanocytes to make them vaporize and carbonize. The operation is simple and safe, but it is difficult to control the depth of treatment and may not be complete or leave scars. Cryotherapy is the treatment of melanocytes by destroying them at low temperature with liquid nitrogen. It is also simple to operate, but has a high recurrence rate and requires multiple treatments, which may cause skin atrophy. Surgical treatment is widely used, has the best treatment effect and the lowest recurrence rate, but has the disadvantage of requiring incisions and sutures, which may leave scars. In general, moles have a low chance of malignant change, so there is no need to be overly nervous and worried. However, moles on exposed areas should be careful to avoid excessive sun exposure, especially in summer, and moles on the palms and soles of the feet should be protected from malignant changes due to long-term friction. Once a mole has a tendency to become malignant, you should go to a regular hospital dermatology department as soon as possible.