Nevus generally refers to pigmented nevus. Pigmented nevus with itching is considered to be caused by allergy, skin inflammation, malignant changes and other factors. 1. Allergy: if the area of pigmented nevus comes into contact with allergic substances, such as pollen, willow, etc., a perverse reaction will occur causing itching symptoms. 2. Skin inflammation: if the area of nevus has skin inflammation, such as bacterial or fungal infection, it will also stimulate the skin to itch, usually accompanied by pimples, papules and other lesions. 3. Malignant transformation: A very small number of pigmented nevi may become cancerous, especially if the size of the nevus is large, the risk of malignant transformation will be higher, usually there will be mild pain and burning and itching, and it will suddenly become bigger and deeper in color, and there are symptoms such as ulceration and bleeding. Pigmented nevus with itching may also be other reasons, it is recommended to go to the hospital in time, after clarifying the cause of standardized treatment.