1. Gastrointestinal Endoscopy Center, Hue University of Medicine and Pharmacy, Hue University, Hue City, Vietnam
2. Department of Internal Medicine A, University Medicine Greifswald, Germany
3. Pathology Department, Hue University of Medicine and Pharmacy, Hue University, Hue City, Vietnam
4. Gastroenterology & Hepatology Department, Fujita Health University, Toyoake, Japan