Objective To investigate the clinicopathological characteristics and prognostic factors of different histological subtypes of intrahepatic cholangiocarcinoma (ICC).

Methods The retrospective cohort study was conducted. The clincopathological data of 171 patients with ICC who underwent initial curative resection in Peking University People′s Hospital from January 2015 to December 2023 were collected. There were 94 males and 77 females, aged 60(range, 53-68)years. Measurement data with normal distribution were expressed as Mean±SD, and comparison between groups was conducted using the independent sample t test. Measurement data with skewed distribution were expressed as M(range), and comparison between groups was conducted using the Mann‑Whitney U test. Count data were described as absolute numbers, and comparison between groups was conducted using the chi‐square test or Fisher exact probability. The Kaplan‐Meier method was used to draw survival curve and calculate survival rates, and the Log‑rank test was used for survival analysis. The COX stepwise regression model was used for univariate and multivariate analyses.

Results (1) Comparison of clinicopathological characteristics of different histological subtypes of ICC. Results of postoperative histopathological examination showed that of the 171 ICC patients, there were 76 cases of large duct type ICC and 95 cases of small duct type ICC. There was a significant difference in cases with concomitant intrahepatic biliary stone between patients with different histological subtypes of ICC (P<0.05), and there were significant differences in cases with concomitant viral hepatitis, cases with CA19‑9 >39 U/mL versus CA19‑9 ≤39 U/mL, cases with CA19‑9 >1 000 U/mL versus CA19‑9 >39-1 000 U/mL, tumor gross morphology, and tumor peri-neural invasion between patients with different histological subtypes of ICC (χ²=8.906, 18.208, 5.689, 43.886, 6.178, P<0.05). (2) Prognostic analysis of different histological subtypes of ICC. Of the 171 patients, 130 cases were followed up for 22(range, 16-43)months, including 63 cases of large duct type ICC and 67 cases of small duct type ICC. The 5‑year overall survival rates of the 63 cases of large duct type ICC and 67 cases of small duct type ICC were 12.60% and 43.70%, respectively, showing a significant difference between them (χ²=5.799, P<0.05). (3) Analysis of prognostic factors for patients undergoing radical resection of ICC. Results of multivariate analysis showed that tumor perineural invasion and lymph node metastasis were independent risk factors affecting overall survival rates of patients undergoing radical resection of ICC (hazard ratio=0.447, 0.383, 95% confidence interval as 0.259-0.771, 0.225-0.651, P<0.05).

Conclusions There are differences in both clinicopatholo-gical characteristics and prognosis between patients with large duct type ICC and small duct type ICC. Tumor perineural invasion and lymph node metastasis are independent risk factors affecting overall survival rates of patients undergoing radical resection of ICC.