Neurodermatitis, also known as chronic simple moss, is a chronic inflammatory skin disease characterized by paroxysmal severe itching and mossy skin changes. This disease is very difficult to treat and is prone to recurrent attacks. Clinical manifestations can be divided into limited and disseminated according to the extent of involvement: 1. Limited: Mostly seen in young and middle-aged people. The lesions are found on the neck, elbows, lumbosacral region, medial femur, female pubic area, scrotum and perianal area, and are mostly confined to one or both sides symmetrically distributed. The basic lesion is a polygonal flat papule of needle point to rice grain size, light red, light brown or normal skin color, solid and shiny texture, the surface can be covered with a small amount of furfurous scales, the lesion gradually fused and expanded, forming moss-like changes, the edge of the lesion can be seen scattered flat papules, the boundary is clear, can be round, round-like or irregular shape. 2. Disseminated: It occurs in adults and the elderly. The lesions are widely distributed on the eyelids, scalp, trunk, limbs, etc., and are mostly mossy, with scratch marks or blood crusts common in and around the lesions. Paroxysmal pruritus is often intensified by local irritation and mental agitation, and is obvious at night. The disease has a chronic course and recurrent episodes that do not heal over the years.