1 Division of Gastroenterology, Department of Internal Medicine, Sapporo Shirakaba-dai Hospital, Sapporo, Japan.
2 Division of Gastroenterology, Department of Internal Medicine, Sapporo Shirakaba-dai Hospital, Sapporo, Japan; Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine, Sapporo, Japan. Electronic address: yadachi@sapmed.ac.jp.
3 Pahology, Sapporo Shirakaba-dai Hospital, Sapporo, Japan.