The correlation between contrast-enhanced ultrasound Liver Imaging Reporting and Data System classification and differentiation grades of combined hepatocellular carcinoma-cholangiocarcinoma.

Background: The contrast-enhanced ultrasound (CEUS) Liver Imaging Reporting and Data System (LI-RADS) classification offers a framework for risk stratification in evaluating liver lesions in patients at risk for hepatocellular carcinoma (HCC). However, its clinical utility in combined HCC-cholangiocarcinoma (cHCC-CCA) has been less extensively studied. The degree of tumor differentiation is clinically significant in determining prognosis, making the analysis of imaging features across different differentiation levels essential. Additionally, studies indicate a correlation between the proportion of HCC and intrahepatic cholangiocarcinoma (ICC) components in cHCC-CCA lesions and their corresponding imaging characteristics. Therefore, the aim of this study was to assess the association of CEUS LI-RADS with the histopathological components and degree of differentiation in cHCC-CCA. Methods: Medical records and CEUS images of patients with cHCC-CCA pathologically confirmed between April 2020 and April 2023 were reviewed. The predominance and degree of differentiation of HCC and ICC components in cHCC-CCA were analyzed via histopathological examination. The chi-square test and two-tailed Student Results: A total of 47 patients with cHCC-CCA were included in this study, comprising 39 men and 8 women, with a mean age of 56.2±8.5 years. A total of 47 lesions were analyzed. These lesions were classified according to the degree of differentiation from lower to higher as follows: poorly differentiated in 20 lesions (42.6%), moderately-poorly differentiated in 17 lesions (36.2%), and moderately differentiated in 10 lesions (21.3%). The CEUS features of lesions with varying degrees of differentiation were analyzed. It was observed that lower degrees of differentiation were associated with more pronounced early washout (P=0.028) and an increased likelihood of being classified as LR-M category under the CEUS LI-RADS classification system (P=0.043). Based on the predominance of pathological components, 36 lesions were pathologically confirmed as HCC predominant, and 11 lesions were confirmed as ICC predominant. Their ultrasound characteristics were analyzed, revealing that ICC-predominant cHCC-CCA lesions were more likely to exhibit regular shape (P=0.013) and well defined margins (P=0.010) and have an early onset of washout (P=0.023). However, the CEUS LI-RADS classification was not effective in distinguishing the predominance of the pathological cHCC-CCA components (P=0.283). Conclusions: cHCC-CCAs classified as LR-M based on CEUS LI-RADS tend to be poorly differentiated, but the dominant pathologic component could be either HCC or ICC. cHCC-CCA lesions with ICC predominance were associated with early washout, whereas HCC-predominant lesions were associated with late washout. Additionally, the margins of HCC-predominant lesions were more ill-defined and irregular in shape compared to those of ICC-predominant lesions.