Pigmented lesions with the following changes often suggest the possibility of early malignant melanoma: i. Color: most malignant melanomas have brown, black, red, white or blue mixed unevenly, when skin pigmented nevi show color changes, special vigilance should be raised;’ ii. Margins: often jagged and jagged changes, which are caused by the tumor spreading and expanding to the surrounding area or self-induced degeneration; iii. Surface: Not smooth, often rough and accompanied by scaly or flaky desquamation. Sometimes there is exudate or blood oozing, and the lesion is higher than the skin surface; 4. The skin around the lesion appears edema or loses its original skin luster or turns white or gray; 5. When the above changes occur, it strongly suggests the possibility of malignant melanoma. Malignant melanoma can occur anywhere on the body, with the lower extremities in women and the trunk in men being the best sites. Any skin lesion with the following characteristics should be suspected of malignant melanoma and further histological examination: i. persistent deepening of brown or black color or discoloration or reddening of the original black lesion; ii. enlargement of the original lesion; iii. elevation of the surface profile of the original macular lesion; iv. jagged edges of round lesions; v. persistent itching, crusting or bleeding; vi. satellite nodules.