1. Gastrointestinal Endoscopy Excellent Center, Department of Medicine; Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society; Bangkok Thailand
2. Departments of Surgery; Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society; Bangkok Thailand
3. Department of Medicine; Police General Hospital; Bangkok Thailand
4. Department of Pathology, Faculty of Medicine; Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society; Bangkok Thailand