1 Fondazione IRCCS Policlinico San Matteo, Pavia, Italy; Department of Surgery, University of Pavia, Italy. Electronic address: a.pietrabissa@smatteo.pv.it.
2 Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
3 Fondazione IRCCS Policlinico San Matteo, Pavia, Italy; Department of Surgery, University of Pavia, Italy.