Junctional nevus excision edge left about 1-2 millimeters can be. Junctional nevus belongs to nevus cell nevus, originated from melanocytes, it is a common benign skin tumor, located at the junction of dermis and epidermis, it can occur in any part of the body, and its color can be black, brown or tan. Junctional nevus usually has no obvious clinical symptoms, and will not change after expanding to a certain extent, so it is sufficient to keep 1-2 millimeters distance from the cutting edge during surgical excision, and there is no need to expand the excision. If there is a risk of malignant transformation, the margins need to be enlarged, and it is recommended to consult the surgeon for the exact extent of excision.