Nevus pigmentosus is a benign congenital tumor composed of pigment cells, most commonly found in the skin, preferably on the face, neck, back and other parts of the body, with a few occurring in the mucous membranes. It varies in size, color and shade, and occasionally see pigmentless nevus. The surface of nevus is either smooth, hypertrophied, or rough in the form of warts, papillae, or nodules with tips, and some of them are accompanied by hair growth. Pathologically, nevi are divided into three categories: junctional nevi, intradermal nevi, and mixed nevi according to the level of nevus cells in the skin. In addition, they are also categorized into giant nevi and blue nevi according to their clinical characteristics. The exact nature and type of the nevus is ultimately diagnosed by tissue section examination. Not all pigmented nevi on the face need surgical treatment. Surgical excision can be considered in the following cases: 1. Preliminary determination of nevus of junction, or those with precursor symptoms of malignancy, such as color change, enlargement of lesions, bleeding and inflammatory changes. 2. 2.With large range, rough surface, nodules, long hairs and so on affecting the appearance. Surgical methods: 1. Excision and suture surgery is suitable for facial junctional nevus, intradermal nevus, mixed nevus with small area, which can be directly sutured after excision. Take forehead nevus excision suture as an example, the introduction is as follows. Design a shuttle-shaped incision on the normal skin around the periphery of the nevus, with its long axis in line with the skin line. The skin tissue involved in the pigmented nevus and a small amount of normal subcutaneous tissue are excised in a wedge shape to make the incision relatively flat after suturing. If the nevus is small in size, it can be directly sutured intradermally with 3/0 non-absorbable thread. Then use 5/0 non-absorbable thread for interrupted skin suture. If the area of nevus is large, subcutaneous separation can be made on both sides of the incision edge to reduce the tension, and then divided into dermal subcutaneous and skin two layers of suture Note: (1) The incision should be 1-2mm from the periphery of the pigment of the nevus visible to the naked eye, so as to avoid incomplete excision and local recurrence. (2) Pathological tissues and part of normal subcutaneous tissues should be excised in a wedge shape, so that the incision is tightly aligned and the surface is smooth after suturing. (3) Large area of intradermal nevus, such as a complete excision can not be pulled together suture, can be sub-surgical excision, the interval between the two surgeries is generally 3-6 months. Complications and prevention: Common complications are incision infection and splitting. Intraoperative attention should be paid to follow the aseptic, non-invasive operation techniques, to avoid the incision under excessive tension suture. 2, excision skin grafting is suitable for extensive area of various types of nevus, after excision can not be directly suture or direct suture may be secondary to the neighboring organs displacement deformity and dysfunction. Take right temporal facial nevus excision skin grafting as an example, the introduction is as follows. The excision area was drawn with methylene blue, and the nevus in the sideburns was preserved in order to be proportional to the contralateral sideburns. Local infiltration anesthesia was applied with 0.25%-0.5% lidocaine solution (containing 1:200,000 epinephrine). Pathologic tissue was excised as designed, and the wound was hemostatic with electrocoagulation or ligation. A full-thickness or thick-medium-thickness skin slice was cut and placed on the trauma, and under normal skin tension, the perimeter of the skin slice was sutured to the trauma margin with interrupted sutures using 5/0 nonabsorbable thread, leaving a long thread for packing. Cover the skin piece with a layer of petroleum jelly gauze, then use gauze and broken gauze to fix the skin piece by packing pressure method, and finally use cotton pads and bandages to fix it by pressure. Points to note: (1) As the change of color and texture of the skin piece after transplantation can affect the effect of appearance after skin grafting, therefore, for the lighter-pigmented nevus of the face, the excision of skin piece transplantation should be taken with a prudent attitude. (2) Generally, if the nevus involves the whole skin layer or the superficial subcutaneous tissue, it can be repaired by skin grafting after complete excision of the pathological tissues to obtain a better effect. Sometimes, the nevus invades into the deep layer of subcutaneous tissues, and if complete excision of pathological tissues is pursued, the deep important nerves (such as facial nerves) may be damaged, and there are often secondary deformities such as indentation in the application of dermal grafting, in which case, the appropriate deep pathological tissues may be retained without excision, and the dermal grafting may be applied to the wound for restoration. (3) The wound should be carefully hemostatized to prevent the formation of hematoma under the skin graft to affect the survival of the skin graft. Complications and prevention: subcutaneous hematoma, skin graft displacement, infection causing skin graft necrosis. Therefore, intraoperative hemostasis should be thorough, and attention should be paid to the packing, pressure and braking of the grafted skin. 3, excision flap transfer surgery is suitable for pigmented nevus with small area, but it is difficult to suture directly after excision, and the surrounding normal skin tissues are loose, which can be used to transfer and repair the nevus after excision, and there is no significant secondary deformity after direct suture in the donor area. It is also suitable for the repair of wounds after excision of various plaque-like lesions on the face. According to the trauma traits and peritraumatic skin tissue, the following local flap transfer repair can be selected. Mainly: (1) local rotational flap method, (2) rhombic excision flap transfer method, (3) double Z rhombic shaped method, (4) rectangular advancement flap method, (5) double axial flap method. According to the specific circumstances of the lesion, personalized design. Points to note: (1) Facial pigmented nevi, plaques and superficial swellings have different sizes and forms, and the shape of the trauma after resection is also different, and its trauma repair is not only the several commonly used methods introduced above, but also a variety of improved methods can be used. Clinical should be combined with the specific circumstances of the wound for flexible choice, the surgeon should be familiar with the various methods, integrated. (2) All repair methods should follow the aforementioned principles of incision design and repair to achieve good results with as little normal tissue loss as possible, no excessive tension in the incision suture, as short an incision line as possible, and no obvious scar. (3) When determining the use of local flaps to repair the trauma after lesion excision, it is necessary to consider whether the flap transfer suture will cause secondary deformities and dysfunctions of the neighboring organs in the donor area. (4) The design of the flap should adopt the retrograde design method to repeatedly verify whether the distal edge of the flap can reach the farthest traumatic edge of the wound after transfer. The range of the cutaneous flap should be slightly larger than the trauma, so that the flap is not enough to repair the trauma after transfer. The length-to-width ratio of the flap should be appropriate, generally should not exceed 2:1, due to the good blood circulation in the face and neck, the length-to-width ratio can be 2.5-3:1. (5) Cutting the flap should not be too thin, especially in the tip of the flap should have a certain thickness to ensure the blood supply of the flap. Even in the rich blood flow of the head and face, the thickness of the flap should be able to retain the subcutaneous vascular network. Complications and prevention: Common complications are ischemic necrosis of the flap tip, infection, scarring and local skin unevenness. Preventive measures lie in careful preoperative design and strict implementation of plastic surgery techniques. Wounds that can be closed with simple methods should never be avoided and repaired with complex methods. Otherwise, the results are often counterproductive. Appearance of the above unsatisfactory results, need to wait for half a year before considering further repair, do not rush to deal with, practice has proved that it is difficult to achieve the expected results of too hasty treatment.