Nevus is a type of pigmented nevus, which has different names due to its different shapes and sizes, such as “spot nevus”, “black hair nevus”, “animal skin nevus”, “giant nevus” and so on. It is a benign tumor formed by the local aggregation of nevus cells. These nevi are usually dark brown or black in color, partly accompanied by hair growth, rough in texture, and often raised in a nodular or irregular manner. Most nevi appear at birth, and a few gradually appear as the infant ages, but early-onset and late-onset nevi are identical in pathology and presentation, both of which are called congenital nevi. Some patients have small lesions around a giant nevus or elsewhere on the body, called satellite lesions. If the lesions involve the limb, they may lag behind the development of the healthy limb. The incidence of giant nevi is about 1/20,000, and there is no difference in the incidence between men and women. Moles are classified into 3 categories according to their maximum diameter: small moles (<1.5 cm), medium-sized moles (1.5 cm-19.9 cm), and giant moles (≥20 mm). In addition, if the size of a mole exceeds 2% of the body surface area, or if the size of a mole on the head is equivalent to 1 palm of the patient's hand and the size of a mole on the rest of the body is equivalent to 2 palms, it is called a giant mole. It should be noted that moles in infants and children gradually increase in size as they get older. A mole of 9 cm in size on the head and 6 cm on the body of an infant will eventually approach 20 cm, so the diagnostic criteria for newborns or infants is that a mole of more than 9 cm on the head or 6 cm on the trunk should be called a congenital giant mole. Congenital giant nevus becomes a huge psychological stress for both the affected child and the parents. Especially, families encounter such children without authoritative institutions to consult on treatment methods and prognosis, thus becoming more anxious. In fact, most of the congenital giant nevi can be treated with good results. The purpose of this article is to spread some knowledge to the parents of the affected children and reduce some unnecessary anxiety. The principle of treatment for giant nevus is to remove the nevus and bring the trauma to normal coverage. Regardless of which treatment method is used, the risk of malignant change, aesthetics and function after treatment should be considered. There are 2 main types of treatment for giant nevi: one is the use of grinding to remove the nevus cells from superficial areas. This method requires that it be performed as early as possible, even within the first few weeks of life. This is because at a young age, nevus cells tend to be located in the superficial layers of the epidermis and dermis, and as the child gets older, the nevus cells gradually migrate to the deeper dermis, thus losing the opportunity for grinding. Grinding methods can remove most of the nevus cells, and the remaining skin cells in the deep dermis can be regenerated to repair the abraded wounds, and the regenerated skin will have superficial scarring. These methods require pathological examination prior to surgery to determine that the nevus cells are more superficial. Although this method can remove most of the nevus cells, there will still be a small amount of nevus cells remaining, so long-term follow-ups are required after surgery to observe whether there is any recurrence. The other method is to use surgical procedures to completely remove the mole and then transfer the skin from the normal area to cover the wound, usually using implants or expanded skin. Implantation is still the treatment of choice for many doctors, and it can cover the wound well after removal of the nevus. However, contracture, hardening or hyperpigmentation of the skin fragments after skin grafting remains a clinical challenge. In addition, large skin extraction areas often have obvious scarring, and some patients may even develop scarring hyperplasia in the donor area, causing itching and discomfort. In pediatric patients with small body surface areas, the trauma caused by skin removal is often even more alarming. If the skin graft area is located in an exposed area such as the face or neck, the aesthetics are seriously affected. After removal of nevus from the extremities and treatment with skin grafting, the lack of local fat tissue often causes local depression, resulting in poor morphology. The growth rate of the transplanted skin is often too slow compared to the surrounding normal skin. Therefore, as the child grows, secondary treatments such as skin grafting are often required. Currently, the widespread clinical use of skin tissue expansion has brought a new light to trauma coverage. Skin tissue expansion involves the burial of a water bladder-like expansion device underneath normal skin. By slowly injecting water into the balloon, the normal skin on its surface gradually expands and increases in size. It is this excess healthy skin that the surgeon uses to cover the wound after removal of the mole. Compared to skin grafting, the flap has the following advantages: (1) The expanded skin area can be directly pulled together and sutured without forming large sheet scars, leaving only thread-like suture scars. (2) The expanded flap usually includes skin and subcutaneous fat tissue. The color, texture, and suppleness of the wound repaired with this flap are the same as normal skin. (3) The expanded flap has the function of sweat and sebaceous gland secretion and can gradually increase in size as the child grows, which are advantages that implantation methods do not have. Many patients, although treated with skin implants when they were young, still require the expander method to treat the area of the nevus and the scar of the skin extraction area when they grow up. However, some patients may lose the opportunity to have an expander flap treatment because of the large area of skin removed and the small amount of healthy skin left on the body. Still, flap surgery has a very important role to play in temporarily relieving the parents' heartache. Another issue is about the timing of the surgery. Both domestic and international experts currently recommend early surgery. This is because giant nevi (especially when located in the head, back of the neck, paraspinal area, or with satellite lesions) are prone to malignant transformation into malignant melanoma or neurocutaneous melanocytosis. The incidence of malignant melanoma is 0-4.9% when the lesion is <20 cm and 4.5%-10% when the lesion is >20 cm. Almost half of the malignant changes occur before the age of 3 years. The risk of congenital giant nevus in children is 16 times higher than that of normal children. When you look at the above data, parents of children with nevi should not worry too much, as the chance of malignant transformation is still relatively small. The above statistics are from international professional literature, but I have not been able to find accurate statistics on the malignancy rate of congenital macromegaly in China. 10% malignancy rate is what is the concept? Today’s American women also have a 10% lifetime chance of developing breast cancer. If the mole rapidly increases in size within a short period of time, becomes lighter in color or darker and shinier, has localized itching, burning or pain, and has surface hair loss, redness, or rupture, the possibility of malignant change of the mole should be considered, and the patient should go to the hospital immediately to have the tissue biopsied. From the perspective of preventing cancerous changes, the earlier the surgery, the better. Most of the giant nevi in various parts of the body can be removed by dilator treatment. In some severe cases, even if all the nevi cannot be removed, it is possible to reduce the amount of melanocytes to a large extent to reduce the chance of malignancy. In addition to preventing malignant changes, there are several other reasons to support early treatment: 1) the skin of infants and young children grows rapidly, which facilitates the expansion of new skin; 2) psychologically, early treatment reduces the psychological burden of parents and children. If treatment can be completed before school age, the psychological impact on the child can be effectively reduced. 3.After 6 months to 1.5 years old, the child’s mobility is weak and easy to control, which is the “golden period” for dilator treatment. Children over 2 years of age can also be treated with dilators, but as they become more mobile, the difficulty and risk increases compared to the previous period. In terms of daily care, it is important to avoid sun exposure to prevent excessive UV damage, but infants and children need moderate sun exposure and can wear sunscreen when they go out. For dry and itchy areas, moisturizing creams such as Vaseline can be applied under medical supervision.