Malignant melanoma is a rare malignant tumor of the skin, also known as nevus cancer or melanoma, which is caused by long-term or repeated adverse stimulation of nevus or pigmented mother spots. It occurs mostly in the skin or mucous membranes close to the skin, but also in the soft brain membrane and choroid. The incidence rate varies according to ethnicity, region and race, and is much higher in Caucasians than in Blacks. Although China is a low incidence area for melanoma, the incidence rate has been on the rise in recent years. In recent years, with the promotion of the TV series “Do Not Disturb II” and related TV health programs, people are paying more and more attention to this disease. Malignant melanoma is most commonly found on the skin, but can also be seen under the nails of the fingers or toes, or on the mucosa inside the mouth, vagina, or anus. Primary malignant melanoma can also be seen in the meninges, iris, and ciliary body. Pathogenesis It has been reported that 84% of malignant melanomas arise from benign moles. The true cause of malignant transformation of normal melanocytes is unknown and is associated with atmospheric pollution, overstimulation, frequent friction, inappropriate injury, immunodeficiency, and race. During pregnancy, moles often change in shape and size, and there is no evidence that pregnancy increases the likelihood of malignant transformation of pigmented nevi to melanoma. Signs of malignancy Pigmented nevi should be seen early if the following manifestations occur: accelerated growth or appearance of multiple small pigmented nevi around the original nevus, i.e. satellite foci; deepening or discoloration of color, especially the spread of hyperpigmented areas to the surrounding normal skin; changes in surface features and texture and shape, especially inflammatory reactions in the skin around the nevus; occurrence of ulcers, itching or pain; rupture and bleeding when washing the face or slight touching, etc. The manifestations of malignant melanoma are more common in middle-aged and elderly people, and more men than women. It is mostly found on the feet of the lower extremities, followed by the trunk, head and neck, and upper extremities. They often appear as rapidly enlarging melanotic nodules. In the early stage, pigmentation may occur in normal skin, or pigmented nevi may increase in pigmentation and deepen in black color, and then the lesions may expand, and some of them may be accompanied by itching and pain. The lesions may be elevated, patchy, nodular, or cauliflower-shaped. When the lesions grow into the subcutaneous tissue, they appear as subcutaneous nodules or masses. Lymph node metastasis often occurs, with advanced metastasis to lung, liver, bone, brain and other organs. The diagnosis of melanoma can be confirmed by biopsy as soon as signs of malignancy or suspected malignancy are detected. Differential diagnosis mainly includes basal cell carcinoma, seborrheic keratosis, dysplastic nevus, blue nevus, dermatofibroma, various pigmented nevi, etc. Skin biopsy is the most accurate method of confirming the diagnosis. Complete radical surgery must be performed only after a definite pathological diagnosis is available.