Pigmented nevi can be broadly divided into two categories: congenital and acquired. Congenital pigmented nevi are relatively rare, and according to statistics, 1% of newborns have pigmented nevi. The larger the diameter, the higher the chance of malignant transformation. For example, some moles with a diameter greater than 20 cm are called congenital giant moles, which are very prone to malignant transformation. Moles that occur after birth are called acquired pigmented nevi, and acquired pigmented nevi rarely grow to be particularly large. There are generally three types of pigmented nevi: the first one is flat and black, called junctional nevus; the second one bulges slightly and is black or light brown, called compound nevus; the third one is hemispherical and bulges on the skin surface, the color is not necessarily black, some of them may be about the same color as the skin, and there may be one or several hairs in the center, which is an intradermal nevus. Generally speaking, pigmented nevi will gradually increase after birth and generally reach a peak around the age of 30, after which some of them will fade away on their own. Most of the newly born nevi in children and young people are junctional nevi, then these nevi gradually evolve into compound nevi, and most of them eventually form intradermal nevi. Most of these moles do not need treatment, but some moles grow on the face and affect the appearance, and some moles have a higher risk of malignant transformation, which can be removed by different methods. The following methods are commonly used: surgical excision, laser, freezing, electrocautery and chemical erosion, etc. The effective and safe methods are surgical excision or laser removal. For flat pigmented nevi (junctional nevi) with a diameter of less than 2 mm, laser treatment can be chosen because the laser can cleanly remove the nevus cells and the skin defect smaller than 2 mm can be completely repaired by the surrounding normal tissue, usually without scar formation. If the nevus is larger than 2 mm, surgery is the first choice. This is because if a nevus larger than 2 mm is treated with laser, the defect formed by cauterization will not be repaired by normal skin, so it will easily leave obvious scars and affect the beauty. Cosmetic suturing of the skin allows for complete skin repair with less visible scarring. Which moles should be removed? Mainly considering the risk of malignant transformation and aesthetic factors, the following six cases should be considered for removal 1.Congenital pigmented moles with large diameter, especially those larger than 6cm. 2.Moles that grow in special areas. Including moles that grow on the palms of the hands, soles of the feet, under the nails, glans, foreskin and oral mucosa, etc., must be observed carefully because moles in these places have a greater chance of becoming malignant melanoma than moles in other places. 3.Moles that grow in areas that will be rubbed for a long time, including armpits, groin, bra area, etc. 4.Moles with atypical changes, such as moles that are very black, uneven pigmentation, uneven or irregular edges, unknown boundaries, asymmetric left and right, pseudo-feet sticking out from the periphery, and larger than 5 mm in diameter. 5.Moles with abnormal sensations, such as pain, itching, redness, swelling, breaking, bleeding, etc. 6.Moles that affect aesthetics can be removed according to the patient’s request. Before pigmented mole removal, patients should be asked in detail whether they have keloid, so as to avoid leaving behind scar proliferation leading to serious consequences. It is also necessary to pay attention to the gap between patients’ expectations and actual treatment results to avoid medical disputes. In general, most pigmented nevi do not need to be treated, and those that need to be removed can be treated with good results if the right method is chosen.