Melanoma is a highly malignant tumor that progresses rapidly and has a very poor prognosis once distant metastases occur. According to statistics, the five-year survival rate for stage IV patients who develop distant organ metastases is less than 5%. Once triggered, melanoma is a serious threat to patient health. The incidence of melanoma is closely related to ethnicity and is a common type of tumor in the predominantly Caucasian European and American countries. In China, the incidence of melanoma is low, but has been growing rapidly in recent years. Cutaneous melanoma can arise from dysplastic nevi and congenital pigmented nevi with malignant transformation. Pigmented nevi on the skin develop from neural crest precursor cells and can be divided into congenital pigmented nevi and acquired pigmented nevi according to the time of onset. Some dysplastic pigmented nevi are large in size and have serious impact on appearance. 1. Congenital pigmented nevi are mostly present at birth, vary in size and have hair attached to them. Therefore, people often call congenital melanocytic nevus as “black hair nevus” or “animal skin nevus”. The chance of congenital nevus becoming malignant is higher than that of common acquired nevus, especially some congenital giant nevus with large area is very easy to become melanoma, so early complete removal is recommended. 2.Acquired pigmented nevi are pigmented nevi that appear in children and adolescence. According to different appearance, they can be divided into common junctional nevus, mixed nevus, intradermal nevus, and special types of halo nevus, macular nevus, nevus of Ota, blue nevus, Spitz nevus, Baker’s nevus and so on. Among them, blue nevus (pigment is located deep in the dermis, which shows blue nodules with clear boundaries), junctional nevus (black or brown pigmented nevus that is not high on the surface of the skin or slightly higher than the surface of the skin) and other pigmented nevi with a certain chance of malignant transformation, which need to be removed early and completely according to the actual situation. Spitz nevus is easily confused with melanoma pathologically, so it needs to be carefully confirmed with the clinical situation. Malignant transformation from atypical pigmented nevus to melanoma is a lengthy process, which may involve activation of various oncogenes such as NRAS, BRAF and CKIT and activation of various pathways such as RAS-RAF-MEK-ERK and PI3K-AKT. Long-term exposure to sunlight and constant and repeated frictional stimulation may cause malignant transformation of pigmented nevi. Since melanoma often arises from the malignant transformation of epidermal nevi. We must master the method of differentiating melanoma from common nevus. There are ABCDE principles summarized abroad: 1. symmetry: benign moles are often symmetrical round or oval in shape; while malignant melanoma is asymmetrical in both halves; 2. border: benign moles have smooth edges and clear borders with surrounding skin; while malignant melanoma has uneven edges and becomes jagged or burr-like changes; 3. color. Benign moles are usually tan, brown or black; mostly monochromatic. 4.Diameter: benign moles are usually less than 5 mm in diameter, while malignant melanomas are larger than 5 mm in diameter; 5.Overall evaluation (Evolution) and other symptoms: if the original pigmented mole suddenly increases in size, changes shape rapidly, deepens color suddenly, or breaks down or bleeds in the near future (mostly 3 months), it is necessary to be alert to malignant transformation. possible. Once a nevus with the above characteristics is found, it is recommended to consult the dermatology department, and if necessary, a complete excisional biopsy should be performed to obtain pathology (not partial excision) for further clarification. The prognosis of melanoma is very poor once distant metastases appear. For melanoma with regional lymph node metastasis, it is still possible to achieve radical cure by combination of extended resection of the primary site and regional lymph node dissection, supplemented with appropriate medications. For stage IV melanoma with distant organ metastasis, although it is not curable yet, remission can be achieved for a certain period of time with appropriate chemotherapy regimens. Meanwhile, as research continues, it is realized that advanced melanoma is a highly immunogenic malignancy. Targeted therapeutic agents designed and made for specific mutations in its signaling pathways can often achieve longer remission. In addition, the emergence of immunotherapy represented by vaccines and immune checkpoint inhibitors in recent years is expected to bring greater breakthroughs in the treatment of advanced melanoma. Recently, it was reported that former U.S. President Jimmy Carter had liver metastases from melanoma and achieved complete remission after treatment with PD-1, an immune checkpoint inhibitor. It is believed that in the near future, melanoma will finally be conquered by modern human medicine.