Pathology of anomalous junction of the pancreaticobiliary ductal system: mutagenicity of the contents of the biliary tract and nuclear atypia of the biliary epithelium.

Congenital biliary dilatation is frequently complicated by biliary tract cancer, and anomalous junction of the pancreaticobiliary ductal system, a major factor constituting the pathology of this disease, is considered to be important as a background for carcinogenesis in the biliary tract. To clarify the mechanism of carcinogenesis in the biliary tract under the circumstance of anomalous junction, we evaluated the mutagenicity of the contents of the biliary tract in patients with congenital biliary dilatation and analyzed the nuclear atypia of the biliary epithelium by fluorocytometry. A mutagenicity test using Bacillus subtilis showed positive results in 6 of 12 patients. Since mutagenicity correlates well with carcinogenicity, these results suggest the necessity of separation surgery between the bile and pancreatic ducts in patients with anomalous junction regardless of the presence or absence of biliary dilatation. On the other hand, DNA histograms of the nuclei of gallbladder epithelial cells produced by fluorocytometry in 4 patients revealed a high incidence of polyploid DNA in 2 patients with marked hypertrophic changes. These patients were also positive for mutagenicity of the contents of the biliary tract, suggesting that mutagens are involved in the atypia at the cellular and nuclear levels.