1. Digestive Surgery Service, Department of Surgery, Hospital de Santo António, Largo Professor Abel Salazar, 4099-003 Porto, Portugal
2. Department of Community Health, Instituto de Ciências Biomédicas Abel Salazar, Rua Jorge Viterbo Ferreira No. 228, 4050-313 Porto, Portugal
3. Pathological Anatomy Service, Department of Pathology, Hospital de Santo António, Largo Professor Abel Salazar, 4099-003 Porto, Portugal
4. Department of Pathology and Molecular Immunology, Instituto de Ciências Biomédicas Abel Salazar, Rua Jorge Viterbo Ferreira No. 228, 4050-313 Porto, Portugal