The growths that grow on the skin are generally benign and most people do not care about them. However, over time, benign skin growths may be transformed into malignant skin cancer, especially when the following early signs appear, it is necessary to seek medical treatment in time. I. Black nevus usually appears from birth to 30 years old, and the appearance of new black nevus after 30 years old should be suspected. II. The skin growths repeatedly appear red, swollen, painful and oozing. III. When the skin growth has a tendency to bleed. IV. Sudden appearance of persistent itchiness in the skin growth. V. Inflammatory redness around the skin growth, or satellite nevi appearing around it. Sudden loss of existing hair on the skin growth. The surface of the skin growth is moist or has crust formation. When the skin growths are repeatedly stimulated by friction or trauma, and there are potential cancerous factors. When hard nodes or ulcers or bleeding appear in the center of the skin growths. X. When the skin growths increase rapidly within a short period of time, it is an early sign of cancer.