Sebaceous nevus is a misshapen tumor composed of sebaceous glands, also known as organoid nevus. Sebaceous nevus is more common and usually develops at birth or shortly after birth, usually on the head, face or neck, especially on the scalp. Clinical manifestations Most nevi develop at birth or shortly after birth, usually on the head, face or neck, especially on the scalp. The majority of cases are solitary. There is no hair growth on the surface of the scalp. In childhood, it appears as a limited patch of hairless surface, slightly elevated, with a smooth, waxy, yellowish surface (Figure 1). In adolescence, the lesion thickens and enlarges, with a papilloma-like elevation (Figure 3). In older patients, the lesions tend to be warty, firm, and may be tan in color (Figure 4). In a few patients, adnexal tumors (Figure 5), such as sweat gland tumors, may develop on top of the disease and may even metastasize. Concomitant abnormalities of other systems, such as the nervous system, are called sebaceous nevus syndrome, the latter being a subtype of epidermal nevus syndrome. The diagnosis is not difficult based on the age of onset, the location of the rash and its manifestations. The diagnosis can be confirmed if there is an increase in sebaceous gland tissue on histology or if there is an abnormal development of the epidermis, dermis or epidermal appendages. Sometimes it needs to be distinguished from juvenile yellow granuloma, verrucous nevus, and papillary sweat duct cystadenoma, when pathological examination is required. Treatment As its gradual proliferation not only affects the appearance but also causes psychological stress to the patient, complete surgical excision is necessary to prevent the occurrence of tumor, and it is better as early as possible. Figure 1 Childhood stage, manifested as a limited surface hairless plaque, slightly elevated, smooth surface, pale yellow. Skin expansion was used (preoperatively) Figure 2, six months after surgery, with good results. Figure 3 The damage thickens and enlarges at puberty, with a papilloma-like elevated surface. Figure 4: The lesions are mostly warty and firm in elderly patients. Figure 5 Sebaceous nevus with concomitant sweat duct cystadenoma (before excision). Figure 6 Six months after the operation, the scar of the incision was not obvious.