Almost everyone will have “black moles”, which are also called pigmented moles and are commonly known as various benign melanocytic tumors. Therefore, don’t panic if you have moles on your body, and don’t talk about them. Moles are medically called nevus cells or melanocytic nevi, which are skin manifestations caused by the increase of melanocytes in the epidermis and dermis. The pressure of modern life and environmental changes make many people grow a lot of moles, but most of these are normal. The main points of differentiation between ordinary moles and malignant melanoma: 1. Asymmetry: ordinary moles are often round or oval, and when one part is divided into two, the two halves are symmetrical, while malignant melanoma is often irregularly shaped, with one side of the rash being more stable and the other side expanding to the periphery, and showing irregularity and epidermal roughness. 2. Edge: The edge of common nevus is smooth and complete and clearly demarcated from the surrounding skin, while the edge of malignant melanoma is often unclear. Or one side is clear while the other side is blurred, giving a vague feeling. 3. Color: Common moles are often brownish yellow, brown or black, while malignant melanoma is mixed with red, white, blue-black and other colors on top of brownish yellow and brown. 4.Growth: The rash grows rapidly in a short period of time and multiplies within 1-2 months. Congenital pigmented nevus rash with a diameter greater than 6 mm, especially those occurring on the palms of the hands and soles of the feet with a diameter of more than 15 mm, has suggested the possibility of malignancy. 5. Whether the rash is elevated or not: The surface of the rash is not elevated at first, then slightly elevated and gradually forms nodules. Or if the surface has vesicles, crusts, pus, running water, especially bloody water, the possibility of malignancy should be considered. Some self-conscious symptoms are also danger signs, such as itching, pain, burning sensation, redness and swelling, or the appearance of new small black spots (satellite foci) within 2 cm around the pigmented nevus. Especially pigmented nevi growing on the palms of hands, soles of feet, finger (toe) nails, waist, shoulders and other friction areas should not be ignored. For suspicious lesions, you should consult a doctor in time and give examination (biopsy) and treatment under the guidance of a physician, and do not panic.