A proposal of imaging classification of intrahepatic mass-forming cholangiocarcinoma into ductal and parenchymal types: clinicopathologic significance

Abstract

OBJECTIVES: To investigate the clinicopathologic significance of a subclassification of mass-forming intrahepatic cholangiocarcinoma (MF-iCCA) into ductal and parenchymal types based on magnetic resonance imaging (MRI) METHODS: We enrolled 72 consecutive patients, in whom MF-iCCA was diagnosed on preoperative MRI and surgical resection from January 2000 to March 2013. Two readers independently evaluated MRI findings of adjacent bile duct dilation, periductal tumor spread, and presence of diffuse dilatation or abnormality of the intrahepatic bile duct. MF-iCCAs with none of the aforementioned findings were defined as parenchymal type, and those with one or more findings were defined as ductal type. The enhancement pattern in the arterial phase was also evaluated. Clinical and histopathological findings, as well as post-surgical outcomes, were collected from medical records.

RESULTS: Parenchymal-type MF-iCCA (21/78, 27%) exhibited significantly lower serum carbohydrate antigen 19-9 (12.8 vs. 173.8 U/mL) and carcinoembryonic antigen (1.7 vs. 4.2 ng/mL), more frequent viral hepatitis (43% vs. 18%), less frequent biliary intraepithelial neoplasia (0% vs. 26%), and less frequent perineural invasion (0% vs. 59%) and lymph node metastasis (7% vs. 46%), compared with the ductal type (57/78, 73%) (p < 0.05 for all). Parenchymal-type MF-iCCA showed more frequent arterial hypervascularity (p = 0.001) and better overall survival (p = 0.030) than the ductal type.

CONCLUSION: Subclassification of MF-iCCAs into parenchymal and ductal types may be useful to discriminate clinical and histopathological characteristics and post-surgical outcomes.

KEY POINTS: • We propose subclassification of mass-forming intrahepatic cholangiocarcinoma (MF-iCCA) as parenchymal and ductal types, on the basis of magnetic resonance imaging findings of biliary abnormality. • Two types of MF-iCCAs exhibit different clinical and histopathological characteristics and post-surgical outcomes.