Differentiating Hepatic Perivascular Epithelioid Cell Tumor from Hepatocellular Carcinoma without High-Risk Factors using Contrast-Enhanced Ultrasound

Background: Hepatic perivascular epithelioid cell tumor (PEComa) is a rare tumor with malignant potential that is frequently misdiagnosed as hepatocellular carcinoma (HCC), despite requiring distinct treatment approaches. This study retrospectively investigated the imaging characteristics of PEComa and HCC without high-risk factors using conventional ultrasound (CUS) and contrast-enhanced ultrasound (CEUS) to improve preoperative diagnostic accuracy. Materials and methods: Sixteen patients with pathologically confirmed PEComa and 31 patients with HCC and no known high-risk factors underwent preoperative ultrasound examinations. Imaging features from CUS and CEUS were systematically reviewed and compared. Independent predictive factors of PEComa were identified using multiple logistic regression analysis and diagnostic performance was assessed through receiver operating characteristic curve analysis. Bootstrap validation and optimism correction were applied to assess the stability and generalization performance. Results: Of the 16 patients in the PEComa group, 11 underwent surgical resection and biopsies were performed in 5. PEComa exhibited distinct CUS imaging features, including a hyperechoic appearance, clear margins, and larger blood vessels around lesions. PEComa was characterized by the absence of necrosis, hyper- or iso-enhancement in the portal phase, isoenhancement in the delayed phase, and prolonged washout time (>180 s) on CEUS. Logistic regression analysis identified hyperechoic appearance, larger blood vessels around lesions, absence of necrosis, and prolonged washout time as independent predictors of PEComa. Integrating CUS and CEUS significantly improved diagnostic accuracy, achieving a sensitivity of 81.25%, a specificity of 96.77%, and an area under the receiver operating characteristic curve of 0.9395. Bootstrap validation and optimism correction confirmed the stability and generalization performance of the combined method. Conclusion: This preliminary study demonstrated that the integration of CUS and CEUS provides high specificity and accuracy in distinguishing hepatic PEComa from HCC without high-risk factors. The identified imaging features should be considered as initial diagnostic indicators, facilitating accurate preoperative differentiation and supporting appropriate clinical management.