Pre-operative Imaging Characteristics in Histology-Proven Resected Intrahepatic Cholangiocarcinoma.

Background: Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) are the most common primary liver cancers. With the increasing incidence of ICC over the past two decades in Asia, it is essential to differentiate between HCC and ICC. However, ICC may mimic the radiological appearance of HCC on computed tomography scans (CT) and magnetic resonance imaging (MRI), leading to misdiagnosis of ICC. The objective of this study is to evaluate and describe the association of specific pre-operative imaging characteristics (arterial enhancement, portal venous washout) in patients with histologically proven resected ICC in our centre.

Methods: Data on patients with histology-proven ICC and mixed hepatocellular-cholangiocarcinomas (HCC-CC) who had undergone surgical resection at Singapore General Hospital (SGH) were identified from a prospectively maintained database. Pre-operative cross-sectional imaging reports were analysed.

Results: Ninety-one patients underwent resection between 1 January 2000 and 31 December 2016. Among those with no risk factors for HCC, a significant percentage of patients with ICC (24.3%) show imaging characteristics of both arterial phase hyperenhancement and non-peripheral venous washout. Among patients with risk factors for HCC, between 20.0 and 33.3% of patients with pure ICC fulfilled the imaging criteria for HCC, and this proportion was generally even higher in the mixed HCC-CC group.

Conclusions: A significant proportion of patients with pure ICC showed pre-operative imaging characteristics which fulfilled the diagnostic criteria for HCC. The differential of ICC should be borne in mind in populations where both malignancies are endemic.