1. Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama 700-8558, Japan
2. Department of Pathology, Okayama University Hospital, Okayama 700-8558, Japan
3. Department of Pathology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama 700-8558, Japan
4. Department of Endoscopy, Okayama University Hospital, Okayama 700-8558, Japan
5. Kawaguchi Medical Clinic, Okayama 700-0913, Japan