1. Department of Otolaryngology, Chinese People's Liberation Army General Hospital, Beijing 100853, P.R. China
2. Department of Otolaryngology Head and Neck Surgery, Bethune International Peace Hospital, Shijiazhuang, Hebei 050082, P.R. China
3. Department of Pathology, Bethune International Peace Hospital, Shijiazhuang, Hebei 050082, P.R. China