MRI features and LI-RADS categorization of combined hepatocellular-cholangiocarcinoma: a scoping review with prognostic implications.

purposeCombined hepatocellular-cholangiocarcinoma (cHCC-CC) is a rare primary liver cancer with heterogeneous radiologic and pathologic characteristics. This scoping review evaluates MRI characteristics of cHCC-CC, its classification using the Liver Imaging Reporting and Data System (LI-RADS), and its association with biomarkers and patient prognosis.

methodsA comprehensive search of medical research databases, grey literature, and references of included studies was performed from inception to September 2024 to identify articles evaluating cHCC-CC using MRI following PRISMA-ScR methodology. We extracted individual MRI imaging characteristics and LI-RADS categorization data to achieve a quantitative summary of the existing literature. A subgroup analysis was conducted for studies that evaluated biomarker and prognostic data.

resultsForty studies including 1767 cHCC-CC cases were evaluated. Most common MRI characteristics included T2 hyperintensity (96%), diffusion restriction (93%), hepatobiliary phase hypoenhancement (91%), arterial enhancement (86%), and non-peripheral washout (83%). Overall, 44-78% of cHCC-CCs demonstrated major LI-RADS features of HCC, 7-31% showed ancillary features that favor HCC, and 10-46% exhibited LR-M characteristics that are classically associated with intrahepatic cholangiocarcinoma (ICC). The majority of cHCC-CCs were accurately characterized as LR-M (57%), but a considerable proportion were categorized as LR-4 (10%) and LR-5 (27%), with the latter demonstrating HCC dominant features. cHCC-CC categorized as LR-M was associated with worse prognosis than those categorized as LR-4 or LR-5. Discordant alpha fetoprotein (AFP) and carbohydrate antigen 19-9 (CA 19-9) values raise suspicion for the diagnosis of cHCC-CC. Due to the rarity of cHCC-CC, there is considerable heterogeneity of the available literature and geographic bias.

conclusionGreater than half of cHCC-CCs can be accurately characterized as LR-M using LI-RADS criteria. However, a large minority are characterized as LR-4 or LR-5, reflecting dominant HCC features. Misclassification of cHCC-CCs as LR-5 can have management implications including inappropriate transplant eligibility. LR-M categorization is associated with worse outcomes, suggesting that LI-RADS categorization has prognostic value. Future integration of imaging features and biomarkers can be used to better evaluate for cHCC-CC.