A pigmented mole does not usually go away on its own and may even grow larger. Nevus pigmentosus is relatively common in clinical practice and is found in many people. Nevus pigmentosus is mainly caused by excessive accumulation of melanocytes in the local area, and is the most common benign skin neoplasm in human beings. Nevus cells usually go through different stages of occurrence, development, maturation and aging. Similarly, pigmented nevi will gradually increase in size and number with age, and sometimes aging will occur. Depending on the site of infiltration, they can be categorized as junctional nevi, intradermal nevi and mixed nevi. Therefore, for those occurring in friction areas or with ABCD phenomenon, i.e. A is usually a gradual increase in the size of the lesion, B is an unclear border, C is an uneven color, and D is an asymmetrical pigmented nevus, it is recommended to surgically excise it as far as possible and to histopathologically examine it. However, most pigmented nevi only affect aesthetics and usually do not require surgical or laser intervention.