1. Department of Otolaryngology, Yidu Central Hospital of Weifang, Weifang, Shandong 262500, P.R. China
2. Department of Return Visit Office, Yidu Central Hospital of Weifang, Weifang, Shandong 262500, P.R. China
3. Department of Pathology, Jilin Cancer Hospital, Changchun, Jilin 130012, P.R. China