Melanoma is a type of malignant tumor, which mostly develops from common melanocytic nevi. Once diagnosed with this disease, surgical removal is necessary. After the surgery, a full-body examination is also required to check whether the tumor cells have metastasized. If there is metastasis, further radiotherapy or chemotherapy is needed. If melanocytic nevi appear on the body, it is crucial to handle them properly, ideally by using laser treatment or surgical removal when they are relatively small to prevent the later formation of melanoma. If the melanocytic nevi cause pain, itching, or oozing after scratching, it might be a precursor to malignancy, and formal treatment is necessary.