Clinicopathological features of cholangiolocarcinoma and impact of tumor heterogeneity on prognosis: A retrospective study in a single institution

Abstract Background: Cholangiolocarcinoma (CLC) is an extremely rare tumor classified as a subtype of small duct-type intrahepatic cholangiocarcinoma (iCCA). There are few detailed reports on CLC, and the prognostic impact of tumor heterogeneity is not clear. Methods: Between April 2006 and June 2022, 14 patients were pathologically diagnosed with CLC through immunohistochemical analysis of their molecular and biological features. Clinicopathological features and prognoses were evaluated retrospectively. Additionally, we compared the tumor heterogeneity, classifying them into pure and partial types according to the CLC component proportion in a single tumor. Results: Chronic liver disease was observed in nine patients (64.3%). All tumors were mass-forming, and pathological R0 resection was achieved in 11 patients (78.6%). Tumor heterogeneity was classified as pure in 11 (78.6%) and partial in three (21.4%) patients. The median follow-up was 59.5 months (12–114 months). There was no difference in the 5-year disease-specific survival rates between the pure and partial (90.0% vs. 100.0%; P = 0.2000) types, but they were significantly higher in the R0 resection group than in the R1 resection group (100.0% vs. 50.0%; P = 0.0253). Conclusions: Our results suggest that CLC has a good prognosis after curative resection, regardless of the proportion of CLC components in a single tumor.