Imaging features of primary hepatic sarcomatoid carcinoma: Differentiation from hepatocellular carcinoma and intrahepatic cholangiocarcinoma on CT: A preliminary study

Purpose: Primary hepatic sarcomatoid carcinoma (PHSC) is a rare type of malignant tumor in the liver. Nevertheless, few studies have focused on the imaging diagnosis of PHSC. In this study, we collected clinical and computed tomography (CT) imaging data of PHSC from two institutions, aiming to investigate the clinical and radiological characteristics of PHSC.Methods: We retrospectively investigated the clinical characteristics and CT features of 22 PHSC patients (19 males and 3 females; mean age, 63.4 years; range, 49 to 76 years), 95 hepatocellular carcinoma (HCC) patients and 50 intrahepatic cholangiocarcinoma (ICC) patients. Two radiolo-gists independently evaluated the CT features of the three groups. Subsequently, we analyzed the differences in the clinical characteristics and CT features between the PHSC and control groups.Results: Most PHSCs were larger than 5 cm (72.7%). PHSC mainly showed irregular (81.8%), heterogeneous (100%) masses with ill-defined (72.7%) borders with necrosis (86.4%) on CT, which are more common CT features versus HCC (p < 0.001). In the arterial phase, PHSC always showed noticeable heterogeneous enhancement (100.0%), mainly manifesting as partial arterial phase hyperenhancement (APHE) (86.4%). The enhancement patterns of PHSC mainly included delayed progressive enhancement (72.7%), nonperipheral washout (22.7%), and unclassified enhancement (4.5%), which were significantly different from the HCC enhancement pattern but similar to the enhancement pattern of ICC. In addition, vein tumor thrombus (18.2%), intra-hepatic metastasis (27.3%), and lymphadenopathy (27.3%) were relatively common in PHSC. Furthermore, most PHSC tumors classified as LR-M (66.7%) were similar to ICC.Conclusions: PHSC generally presents as irregularly large masses with necrosis, intrahepatic metastasis, and lymphadenopathy. The CT enhancement of PHSC is mainly part of APHE and delayed progressive enhancement.