Some malignant melanomas evolve from nevi (especially junctional and compound nevi); others originate from a cutaneous or freckled basis. The true cause of the evolution of nevi to melanoma remains unknown; trauma or various external irritations are often considered as triggers. Although malignant melanoma is a highly malignant tumor that develops rapidly and tends to metastasize widely, its biological behavior is also highly variable. However, its biological behavior is also highly variable, and lesions can remain quiescent for years or only slowly increase in size, or they can increase in size rapidly and metastasize within a short period of time. The clinical symptoms of melanoma need to be understood 1. Superficial spreading type is the most common, accounting for about 70%. It occurs around 50 years old, mostly on the limbs in women and on the trunk in men. The malignancy degree is between freckle type and nodular type. Early manifestations are tan, brown, blue or black, most of them can be rosy or peachy red, and their edges are jagged and make the skin texture disappear. The radiation growth period lasts from 1 to 12 years, and less than 5% of lymph node metastases occur during this period. 2. Freckle type accounts for 10% to 15%, and is the least malignant of the four types. It is most common in the exposed areas such as head, neck and back of hands, mostly seen in 60-70 years old, and is more common in women. Clinically, they appear as large, flat or slightly elevated brown or tan lesions on the skin surface. When the radiation growth is accompanied by vertical growth, the local area is focally elevated and remains brownish-yellow in color, with a lymph node metastasis rate of about 25%. 3. The nodular type is the most malignant of the four types, accounting for about 12% of the cases, and is more likely to occur around the age of 50, with a male to female ratio of 2:1, and is more likely to occur on the back. The clinical nodules are gray with peach color, when the lesion continues to grow its color becomes blue-black, purple-black jam-like dome-shaped or polyp-like masses, vertical growth is its only growth mode, the course of the disease progresses rapidly, generally lasting several months to a year, and early ulceration and lymph node metastasis. The prognosis of this type is poor. Radiation growth phase is brownish-yellow, brownish-brown or black, not higher than the skin surface, if irregular brownish-yellow or brownish-brown streaks are seen under the nail bed, the radiation growth phase lasts about 1 year, if not treated in time, the lesion will enter the vertical growth phase, the lesion will be nodular and the lymph node metastasis rate will increase, the prognosis is also poor.