Etiology: This disease belongs to a congenital verrucous hyperplasia of epidermis, which has existed since childhood. Clinical symptoms: more common in children, the incidence of male and female is equal, can occur in any part of the body. Most cases are verrucous hyperplasia, brown or black. Papillomatoid small tumor, irregular protuberance, greasy surface. The strips are long or short, and the strips are very irregular. No conscious symptoms, just not good-looking. Prevention and treatment: Laser treatment can be performed under local anesthesia, and there are slight marks after operation, but they basically belong to normal skin.