1. Gastroenterology Department, Faculty of Medicine, University of São Paulo, 05403-001 São Paulo, SP, Brazil
2. Pathology Department, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
3. Division of Digestive Endoscopy and General Surgery, Carlos Fernando Malzoni Hospital, Matão, SP, Brazil
4. Digestive Surgery Department, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil