Pigmented nevi are usually recommended to be removed surgically and are not recommended to be removed by mole spotting. A nevus pigmentosa is a hyperplastic lesion that is a mass of nevus cells that accumulates at the junction of the true epidermis or in the dermis and has a black, brown or dark red appearance. Treatment usually involves surgical excision and pathological testing. Microscopic examination is required to determine whether the lesion has been removed and whether a second excision is needed. If the patient uses caustic drops or laser to remove the nevus, it is likely that the nevus cells will not be removed completely, thus leaving the nevus cells in the body and causing the nevus to recur. In addition, the above methods of mole removal may also cause malignant transformation of the nevus, which may turn into malignant melanoma. Therefore, it is recommended that patients who want to remove moles should go to a professional dermatology department for local surgical excision to ensure more complete removal.