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

Combined 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.

A 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.

Forty 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.

Greater 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.