Imaging of combined hepatocellular-cholangiocarcinoma in cirrhosis and risk of false diagnosis of hepatocellular carcinoma

Background: Diagnosis of hepatocellular carcinoma can be achieved by imaging in cirrhotic patients. Combined hepatocellular-cholangiocarcinoma is a primary liver tumor and its imaging patterns have been poorly investigated. Misdiagnosis for either hepatocellular carcinoma or benign lesions can occur. We aimed to evaluate the enhancement pattern of combined hepatocellular-cholangiocarcinoma in cirrhosis with imaging techniques and to estimate the risk of misdiagnosis for hepatocellular carcinoma. Methods: All histology-confirmed combined hepatocellular-cholangiocarcinoma in cirrhosis seen in two Italian centers between 2003 and 2016, in which at least one imaging technique had been performed, was retrospectively collected. The enhancement pattern was analyzed for all available imaging modalities. Results: A total of 37 combined hepatocellular-cholangiocarcinoma nodules were identified. Contrast-enhanced ultrasound, computed tomography, and magnetic resonance imaging had been performed in 27, 34, and 17 nodules, respectively. Contrast-enhanced ultrasound was at higher risk of misdiagnosis for pure hepatocellular carcinoma than computed tomography (p = 0.005) or magnetic resonance imaging (p = 0.040). Only six of 24 combined hepatocellular-cholangiocarcinoma lesions submitted to both contrast-enhanced ultrasound and computed tomography showed coincident patterns; contrast-enhanced ultrasound correctly suggested a condition of malignancy in a higher number of cases than computed tomography (p < 0.001) and magnetic resonance imaging (p = 0.002). Conclusions: Contrast-enhanced ultrasound misdiagnosed a higher number of combined hepatocellular-cholangiocarcinoma as hepatocellular carcinoma than computed tomography and magnetic resonance imaging. However, the latter techniques were able to identify features of malignancy less often.