[Differential diagnostics of inflammatory changes and epithelial neoplasia of extrahepatic bile ducts]

To investigate the histological and immunohistochemical characteristics of epithelial neoplasia of the extrahepatic bile ducts (EHBD) and to develop a diagnostic algorithm.

The study included 104 patients. All patients underwent biliary tract biopsy. Morphological and immunohistochemical parameters were compared in biopsies with inflammation, low- and high-grade biliary intraepithelial neoplasia (BilIN), low- and high-grade intraductal papillary neoplasia (IPNB), and cholangiocarcinoma (CC). The main parameters in the study of the histological characteristics of epithelial neoplasia of the EHBD were: cellular atypia, nuclear polymorphism, nuclear polarity, the state of the brush border, inflammatory infiltration, and histological architecture. Immunohistochemical studies were performed using antibodies to MUC1, MUC2, MUC5AC, MUC6, and CD10. When studying the IHC characteristics of epithelial neoplasms of the EHBD, the localization of the reaction in epithelial cells, its intensity, and prevalence were assessed, and specificity and sensitivity were evaluated. Statistical analysis of the data used the two-sided Pearson χ² criterion (p<0.05).

Based on the results of the morphological stage of the study, a scale for assessing the degree of dysplasia in biopsy specimens was developed; a certain number of points were assigned to each type of epithelial neoplasia of the EHBD. Based on the results of the IHC study, taking into account statistically significant changes, an immunophenotype was established for each type of epithelial neoplasia of the EHBD: inflammation and BilIN LG - MUC1, MUC2, MUC6, CD10; BilIN HG - MUC1, MUC2, MUC5AC, MUC6; IPNB LG - MUC1, MUC2, MUC5AC, MUC6, CD10; IPNB HG - MUC1, MUC2, MUC5AC, MUC6; CC - MUC1, MUC5AC, MUC6. For differential diagnosis of the degree of dysplasia in epithelial neoplasia of the EHBD, it is recommended to use an IHC panel with the presence of antibodies to MUC1, MUC2, CD10. It is proposed to use antibodies to MUC2, MUC5AC and MUC6 as an IHC panel for differential diagnosis of IPNB subtypes.

Clear morphological and immunohistochemical criteria for the differential diagnosis of non-invasive lesions of the EHBD, inflammation and cholangiocarcinoma have been identified, and an algorithm for the comprehensive differential diagnosis of epithelial neoplasia of the EHBD has been developed.