1. Division of Medicine, Department of Upper Gastrointestinal Diseases, Karolinska University Hospital and Karolinska Institute, Stockholm, Sweden
2. Advanced Endoscopy Center Carlos Moreira da Silva, Department of Gastroenterology, Pedro Hispano Hospital, Matosinhos, Portugal
3. Department of Pathology, Karolinska University Hospital and Karolinska Institute, Stockholm, Sweden
4. Department of Gastroenterology and Hepatology, Gunma University Graduate School of Medicine, Gunma, Japan