Cancerous dark pigmented nevi manifest as repeated breakage, blood and oozing, asymmetrical nevi, and an area generally larger than 5mm. these manifestations should be seen as soon as possible, or they can be examined first. For moles with higher risk, such as moles on the soles of feet, edges of toes, palms of hands and edges of fingers, melanoma may occur after long-term friction, and melanoma of extremities commonly seen in Chinese is related to pigmented moles in these areas. Therefore, if moles on the soles of the feet, edges of the toes, palms of the hands and edges of the fingers are found, they should be treated as soon as possible so as to reduce the risk of malignant transformation.