1. Department of Gastroenterology and Metabolism, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan
2. Department of Endoscopy, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan
3. Department of Anatomical Pathology, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan
4. Department of the Faculty of Humanities and Human Sciences, Hiroshima Shudo University, 1-1-1 Otsukahigashi, Asaminami-ku, Hiroshima 731-3195, Japan