Moles with a tendency to become malignant need to be removed. A nevus, scientifically known as a dark pigmented mole, is essentially a benign tumor with abnormal proliferation of melanocytes under the skin. Most people develop moles innately or naturally as they age, and while most moles are harmless, under certain conditions (such as frequent friction, exposure to stimuli, etc.) moles can become cancerous, affecting health and even metastasizing to threaten life. It is important to observe moles. When there is asymmetry of pigmentation, unclear border, color change (appearance of multiple colors), large diameter, and obvious change in a short period of time (including size, color, etc.), it often suggests that there is a tendency for it to become cancerous, and it should be consulted in a regular medical institution in time so as to avoid delaying the condition.