The initial symptoms of flat warts are mainly the localized appearance of raised flat papules, usually arranged in beads and occasionally itchy. Flat warts are caused by human papilloma virus infection, low immunity, trauma and other factors may also trigger the disease. The patient will appear locally above the normal skin of flat papules, the size of a grain of rice or soybean, usually round, hard texture. Flat warts are spread by autologous inoculation through scratching and are usually arranged in beads or strips along the scratches, known as isomorphic reactions. Flat warts are usually normal-skinned or light brown in color, may appear suddenly, and some patients may experience mild itching. If these symptoms occur, it is recommended to go to a regular hospital for examination.