Color: Malignant melanoma is mostly brown, black, red, white or blue mixed unevenly, so be especially vigilant when the color of skin nevus changes. The skin around the focus may appear edema or lose its original skin luster or turn white and gray.

Surface: not smooth. Usually rough with scaly or flaky desquamation. Sometimes there is oozing or oozing blood, and the focus can be higher than the skin surface. It is often serrated and uneven, which is caused by the tumor spreading around or self-collapse.

Abnormal sensation: common local itching, burning sensation or tenderness.