[Pathology of the anomalous choledocho-pancreatic junction--action of pancreatic juice on the biliary tract].

The mechanism of action of pancreatic juice on the biliary tract was investigated in a 5-year-old girl with choledochal cyst and animal models of the anomalous choledocho-pancreatic junction produced by pancreatico-cholecystostomy in 26 dogs. The results are as follows: Pancreatic enzymes are activated when bile and pancreatic juice are mixed in the biliary tract. Successively, lysolecithin and free fatty acids are produced by hydrolysis of lecithin in bile with phospholipase A2. These substances including phospholipase A2 destroy the mucosal barrier. The initial site receiving mucosal damage appears to be the epithelial apical cell membrane. The transfer of phospholipase A2 but not amylase from the biliary tract to the blood stream was suggested by comparing enzyme activity of portal and hepatic venous blood. The presence of some mutagenic substances in the contents of the choledochal cyst was confirmed by Ames assay and Rec-assay. This suggests that activated pancreatic enzymes and successively produced harmful substances in the anomalous choledocho-pancreatic junction are responsible for not only inflammatory but positively carcinogenic action on the biliary tract. In conclusion, the anomalous choledocho-pancreatic junction requires operative separation of the bile duct from the pancreatic duct despite the presence or absence of a choledochal cyst.