1. Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine; Shanghai Jiao Tong University; 160 Pujian Road Shanghai 200127 P. R. China
2. Department of Pathology, Renji Hospital, School of Medicine; Shanghai Jiao Tong University; Shanghai 200127 P. R. China
3. Department of Pathology, Shanghai Ninth People's Hospital, School of Medicine; Shanghai Jiao Tong University; Shanghai 200011 P. R. China