A new model for pancreaticobiliary maljunction without bile duct dilatation: demonstration of cell proliferation in the gallbladder epithelium.

Patients with pancreaticobiliary maljunction without bile duct dilatation (PBMWBDD) develop gallbladder carcinoma frequently. No models of PBMWBDD exist, and no previous studies have clearly demonstrated changes in the gallbladder relating to carcinogenesis. We, therefore, examined the cell kinetics of the gallbladder epithelium in a new experimental model of PBMWBDD. A cat model was produced by performing choledocho-pancreatic side-to-side ductal anastomosis in nine animals. Five cats, in which the choledocho-pancreatic ducts were exposed only, served as controls. After 6 months, the gallbladders of these cats were removed and stained with anti-proliferating cell nuclear antigen (PCNA) antibody (PC10, Dako). The labeling index (LI) was determined from the percentage of positive nuclei in three microscopic fields. The diameter of the common bile duct was not different between the models and the controls. In the models, the number of PCNA positive cells was significantly increased. The mean (+/- standard deviation) PCNA LI was 28.1 +/- 12.2% in the models and 4.3 +/- 1.6% in the controls (P < 0.01). These studies clearly indicate that this model is suitable for studying PBMWBDD and that PBMWBDD has a prominent proliferating effect on the gallbladder epithelium which may play an important role in gallbladder carcinogenesis.