The sudden appearance of peeling skin on the arm is considered in the following cases: 1. Psoriasis vulgaris: peeling skin can appear on the surface of erythematous spots or plaques, mainly due to genetic factors, immune disorder factors, metabolic disorder factors, smoking, trauma, alcohol consumption and other factors. 2. Pityriasis rosea: oval-shaped erythematous spots can appear around the body, including the arm, the long axis of the rash is consistent with the skin line, and there is fine bran-like peeling skin on it. In the etiology is mainly due to viral infection, allergic factors or swimming and other factors. 3, flat moss: may be due to hepatitis virus infection, genetic factors or immune disorders and other factors, can be applied to the treatment of dinaide ointment.