Malignant melanoma occurs in white people, and QueenS-Land in Australia is known as a region with a high incidence of malignant melanoma in the world. The incidence of malignant melanoma in China is not high, but due to the lack of awareness of its severity among doctors and patients, it is usually too late by the time it is diagnosed and the treatment outcome is highly unsatisfactory. The disease occurs in the age of 30-60 years. The rare juvenile malignant melanoma Spity reported 13 cases, aged 1.5-12 years. The younger age group generally has a lower malignancy and a better prognosis after surgical resection. There is almost no difference in gender, but the location of the lesion is related to gender, with males predominating on the trunk and more females than males on the limbs. How to prevent melanoma? 1. Do not stimulate the moles with corrosive drugs or thorough freezing. It is dangerous to repeatedly freeze a mole several times without getting rid of it at one time, because moles often become malignant due to traumatic stimulation. About 30% to 50% of malignant melanoma is related to external stimulation. How to prevent the occurrence of melanoma? If it is for cosmetic reasons, it is safer and more reliable to remove the mole at once, and it is not advisable to over-stimulate the mole to avoid causing malignancy and tumor. 2.For pigmented nevi that occur in easy to rub parts, biopsy should be taken. For example, children with large hairy nevi in the waist, which are often rubbed and squeezed by the belt, should be removed as early as possible. If it is difficult to remove all of them at one time, the main part can be removed first, and then other resections can be made, and all the nevi must be removed cleanly. 3.For the prevention of melanoma, we also need to pay attention to the information of malignant change of nevus, such as enlarged lymph nodes in the area of nevus, blue-black color is vaguely visible; the volume of nevus increases, and the pigment is either dark or light; the nevus expands radially to the surrounding area and other information, so that we can take preventive measures early to avoid the occurrence of melanoma.