Department of Gastroenterology, Yokohama City University Hospital, Yokohama, Japan
2.Department of Pathology, Yokohama City University Hospital, Yokohama, Japan
3.Department of Medical Education, Yokohama City University School of Medicine, Yokohama, Japan
4.Department of Gastroenterology, Yokohama City University Hospital, Yokohama, Kanagawa, Japan