Objective To analyze the B-model ultrasound (BMUS)and contrast-enhanced ultrasound (CEUS)characteristics of hepatocellular adenoma (HCA)and explore the features of inflammatory HCA (I-HCA) and HNF-1α -inactivated HCA (H-HCA). Methods The BMUS features of 103 HCA patients definited by pathology from Mar 2012 to Dec 2020 in Zhongshan Hospital, Fudan University were analyzed retrospectively.A total of 65 patients with 65 lesions underwent CEUS.The enhancement pattern, subcapsular enhancement in arterial phase, enhancement degree in arterial, portal venous and late phase were compared between different molecular classifications of HCA. Results On BMUS, I-HCA was mainly hypoechoic (68.4%, 26/38), while H-HCA was mainly hyperechoic (78.6%, 11/14, P<0.001). Fatty liver was more frequently in I-HCA than that in H-HCA (P=0.025).The detection rate of semicirular or annular blood flow signal in I-HCA was higher than that in H-HCA (50.0% vs 14.3%, P=0.030).The CEUS characteristics of HCA included overall hyper-enhancement (73.8%, 48/65) in arterial phase, homogeneous enhancement (86.2%, 56/65) at the peak, hypo-enhancement in portal venous (15.4%, 10/ 65) and late phase (40.0%, 26/65). Subcapsular enhancement was detected in 50.8% (33/65) of all lesions. The detection rate of subcapsular enhancement in I-HCA was higher than that of H-HCA (54.2%, 12.5%, P=0.040).In late phase, the appearance of hypo-enhancement in I-HCA was higher than that of HHCA (P=0.019). With the characteristic of“hyperechoic on BMUS, homogeneous hyper-enhancement enhancement in arterial phase of CEUS, continuous hyper- or iso-enhancement in late phase”for H-HCA, the sensitivity and specificity were 0.500 and 0.962, respectively.With the characteristic of“hypoechoic with fatty liver on BMUS, semicircular or annular blood flow signal on CDFI, hyper-enhancement in arterial phase of CEUS, and subcapsular enhancement”for I-HCA, the sensitivity and specificity of I-HCA were 0.545 and 0.875, respectively. Conclusion H-HCA is characterized by hyperechoic on BMUS, homogeneous hyper-enhancement enhancement in arterial phase of CEUS continuous hyper- or isoenhancement in late phase.I-HCA is hypoechoic with fatty liver on BMUS, semicircular or annular blood flow signal on CDFI, hyper-enhanced in arterial phase of CEUS and subcapsular enhancement.BMUS and CEUS are helpful for the preoperative diagnosis of HCA. [ABSTRACT FROM AUTHOR]