1. Department of Otolaryngology Head and Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama City, Japan
2. Department of Otolaryngology, Japanese Red Cross Society Himeji Hospital, Himeji City, Japan
3. Department of Pathology, Japanese Red Cross Society Himeji Hospital, Himeji City, Japan
4. Department of Inspection Technology, Japanese Red Cross Society Himeji Hospital, Himeji City, Japan
5. Department of Clinical Pathology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama City, Japan