1. Department of Otorhinolaryngology-Head and Neck Surgery, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8510, Japan
2. Otorhinolaryngology-Head and Neck Surgery, Kinan Hospital, 46-70 Shinjocho, Tanabe 646-8858, Japan
3. Department of Human Pathology, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8510, Japan