Pigmented nevi are very common on the skin and used to be a problem that people did not pay attention to. However, with the release of the movie Do Not Disturb, many fans are worried about their pigmented nevi becoming malignant and have gone to major hospitals to consult or remove them. In fact, some pigmented moles can be accompanied by a lifetime without malignant change, while others need attention and treatment? We found that they have misconceptions among the patients we see, so it is very necessary to help patients to identify them easily. Almost everyone has pigmented nevi, but the number and size vary. If they occur on the face, they may affect the beauty; if they turn malignant, they can be life-threatening. The incidence of pigmented nevi turning malignant is called malignant melanoma, which has a high incidence in Caucasians and a low incidence in people of color, including yellow people, which is obviously correlated with the lifestyle habits – white people in Europe and America like to sunbathe. Not all pigmented nevi are susceptible to malignant changes, but those that do have two characteristics: 1. Junctional nevi are prone to occur: they are black or brown pigmented nevi that are less than 1 cm and not higher than the skin surface. 2. The site of occurrence is obviously related: In Asian people, junctional nevi under the soles of the feet or finger (toe) nails are prone to malignant transformation due to friction or trauma. Therefore, preventive excision can be done. Junctional nevi in other parts of the body are less likely to develop malignancy because they do not rub easily. If a junctional nevus becomes larger and more elevated, it is transformed into an intradermal nevus or a compound nevus, which means that the risk of malignancy decreases rather than increases. During pregnancy, the color of the nevus deepens due to the influence of hormones in the body, which is also a normal phenomenon rather than an omen of malignancy. The manifestation of malignant change of pigmented nevus: The pigmented nevus suddenly becomes larger, grows rapidly, deepens in color or unevenly, the border is not neat, the surrounding area is inflamed for unknown reasons, this inflammation cannot be explained by infection or trauma, easily bleeds or ulcers occur, the phenomenon of satellite appears around the nevus, i.e. multiple star-shaped nevi on the border, and there is infiltration feeling at the bottom when touched, which marks the malignant change of the nevus. Treatment of pigmented nevus: Generally, it does not need to be treated, and the treatment can be surgically removed. If it occurs on the face, laser treatment can be taken according to the situation for the sake of aesthetics, and if it is not a scar, laser will rarely leave a scar. Do not use corrosive agents, as they are prone to scarring, and incomplete treatment may stimulate the mole cells to proliferate and become malignant.