Comparing the computed tomography radiologic features of cytokeratin 19-positive hepatocellular carcinoma to those of conventional hepatocellular carcinoma and intrahepatic cholangiocarcinoma.

Background: Cytokeratin 19-positive hepatocellular carcinoma (CK19 HCC) is an uncommon subtype of hepatocellular carcinoma (HCC). The purpose of this study was to identify radiological characteristics with diagnostic value for CK19 HCC.

Methods: This was a case-control study. A retrospective analysis of 104 patients with surgically resected, pathologically confirmed CK19 HCC was conducted. The contrast-enhanced computed tomography characteristics of the enrolled patients were assessed, and differences in characteristics between groups were identified by statistical analysis. A multivariate logistic regression model was established to identify CK19 HCC, and receiver operating characteristic curves were plotted to evaluate the diagnostic performance of the model.

Results: The univariate analysis revealed that the frequency of regular morphology (55.8% 35.6%, P<0.001), hypodensity (99.0% 91.8%, P=0.010), intratumoral necrosis (61.5% 25.0%, P<0.001), heterogeneous enhancement (96.2% 86.5%, P=0.008), peripheral washout (5.8% 1.4%, P=0.031), non-peripheral washout (88.5% 45.7%, P<0.001), Liver Imaging Reporting and Data System category 5 (67.3% 40.4%, P<0.001), and Liver Imaging Reporting and Data System - Category tumor in vein (LR-TIV) (16.3% 2.4%, P<0.001) were significantly higher in CK19 HCC than the non-CK19+ hepatic tumor patients. Conversely, the incidence of rim enhancement in the arterial phase (7.7% 22.6%, P=0.001), transient hepatic attenuation difference (THAD; 4.8% 23.1%, P<0.001), pseudocapsule formation (12.5% 23.6%, P=0.021), progressive enhancement (5.8% 50.5%, P<0.001), and lymphadenopathy (9.6% 24.5%, P=0.002) was significantly lower in the CK19 HCC than the non-CK19 hepatic tumor patients. The multivariate analysis identified intratumoral necrosis, THAD, pseudocapsule formation, progressive enhancement, and LR-TIV as independent predictors of CK19+ HCC (P<0.05). The joint prediction model had an area under the curve of 0.867 in terms of its ability to detect CK19 HCC, and a sensitivity of 88.46% and a specificity of 69.71%.

Conclusions: CK19 HCC is characterized by an increased prevalence of intratumoral necrosis and LR-TIV, as well as a lower incidence of THAD, pseudocapsule formation, and progressive enhancement, which collectively contribute to the identification of this HCC variant.