Frequent expression of mucin core protein MUC1 in non-neoplastic gallbladder mucosa from patients with pancreaticobiliary maljunction

Background: Gallbladder carcinoma is known to develop frequently in patient s with pancreaticobiliary maljunction, though the causal relationship remai ns speculative. Methods: Histopathologic changes, expression of mucin core protein MUC1 and MUC2, and cell proliferative activities in the gallbladder mucosa from 27 patients with panceaticobiliary maljunction and 21 control gallbladders were examined. Three cases of pancreaticobiliary maljunction w ere associated with gallbladder carcinoma. Results: The lining epithelia of the non-neoplastic gallbladder mucosa of pancreaticobiliary maljunction sh owed frequently papillary hyperplasia and higher proliferative activities, when compared to the control. In 3 cases with carcinoma, MUC1 was expressed on the luminal border and in the cytoplasm of carcinoma cells, particularl y in de-differentiated and invasive areas. MUC1 was variably expressed on t he luminal surface of the lining epithelia of non-neoplastic gallbladder mu cosa in babies, children, youths and adults with pancreaticobiliary maljunc tion. However, such expression was focally seen in 2 of the 21 control case s (p<0.01). MUC2 was scattered in the hyperplastic and carcinomatous epithe lial cells appearing as goblet cells in pancreaticobiliary maljunction and control groups. Conclusions: This study suggests that persistent MUC1 expre ssion and increased cell proliferative activities of non-neoplastic gallbla dder epithelium of the patients with pancreaticobiliary maljunction after b irth reflect an altered phenotype of epithelial cells and these abnormaliti es may be related to carcinogenesis in such patients.