Dermatomal cyst is a congenital disorder, a type of malformation tumor, which is a congenital cyst formed by deviated skin cells from their original base, often located in the head. They are deep, not adherent to the superficial skin, soft and tough, with high tension, and their bases are often immovable with deep tissues such as fascia or periosteum, and may form pressure marks on the local bone surface due to long-term compression. Lipoma is flat and lobulated and located under the skin. If the skin is pushed along the two sides of the mass with fingers, orange peel-like signs may appear. The onset of the disease is early, mostly in children. According to some statistics, 37.2% of the cases existed at birth and 62.7% were found before the age of 5. The growth is generally slow, the volume is small, and the surface skin is freely movable, but the base is often adherent and fixed. The texture is soft, with fluctuating or dough-like sensation. The cysts are unicompartmental, with thick walls resembling intact or less intact skin structures. The innermost layer is the keratinous layer of the compound squamous epithelium, and the remaining layers of the epidermis and the dermis are arranged outward in sequence. The dermal tissue component accounts for about 90% of the cyst wall, and hair follicles, sebaceous glands, sweat glands and other tissues are visible. The cyst cavity is filled with caseous sebum mixed with keratinized material, epithelial debris, cholesterol crystals, hair and thicker fluid, white or yellow in color and odorless. Subcutaneous dermatomal cysts are more common in the orbital region and nasal roots, and submucosal dermatomal cysts can be found in the sublingual and subchin regions. Nasal dermatomal cysts must sometimes be distinguished from gliomas or meningeal bulges, and sublingual and subchin dermatomal cysts should be distinguished from sublingual cysts, hydatid cysts, and thyroglossal cysts. The treatment is complete surgical excision. If the base of the cyst is close to the bone surface, it should be removed together with the periosteum of the part. After cyst removal, if there are deformities such as bone tissue depression, defect or deformation, tissue transplantation can be performed immediately or later to restore normal appearance according to the presence or absence of staining and sterile condition of the wound. For surgical removal, the deeper cysts sometimes adhere to the meninges, so care should be taken not to injure the meninges during surgical excision.