1. Department of Gastroenterology, Aizu Medical Center, Fukushima Medical University, Fukushima, Japan
2. Department of Gastroenterology, Dokkyo Medical University, Mibu, Japan
3. Department of Anatomic Pathology, Kurashiki Central Hospital, Kurashiki, Japan
4. Department of Surgery, Aizu Medical Center, Fukushima Medical University, Fukushima, Japan