Pigmented nevus is a benign tumor composed of nests of melanocytes. From infants to the elderly, almost everyone has it. It can grow in any part of normal people. Based on different locations of melanocytes in the skin, pigmented nevus can be classified into junctional nevus, compound nevus, and intradermal nevus. Some grow on the head and face or the limbs which affect the appearance, while some grow in such friction-prone parts as the palm, sole, neck or back. If the pigmented nevus increases significantly in a short period of time, or leads to itching, burning, inflammation, bleeding, ulceration, etc, it indicates the nevus has a certain tendency for deterioration or may have turned canceration. Clinically, it should be distinguished from many other diseases such as seborrheic keratosis (SK), warts, basal cell carcinoma (BCC), and malignant melanoma (MM), 1 and its diagnosis is usually based on histological examination of skin biopsy. Reflectance confocal microscopy (RCM) is a new non-invasive method based on optical confocal principle with advantages of in situ, in vivo, non-invasive, dynamic, etc. 2 Some studies have described the characteristics of RCM images of pigmented nevus. It usually shows a clear and symmetrical border of the lesion, regular arrangement of the