The purpose of this study was to retrospectively compare the imaging features of hepatic epithelioid angiomyolipoma (HEAML) to those of hepatocellular carcinoma negative for hepatitis B surface antigen and hepatitis C antibody (NBNC-HCC) on contrast-enhanced ultrasound (CEUS) with sulphur hexafluoride microbubbles.

Twenty-two patients (4 men, 18 women) with a mean age of 42.6±10.2 (SD) years (range: 22–63 years) with histopathologically confirmed HEMAL were included in the study. Forty-four patients (30 men, 14 women) with a mean age of 57.3±15.9 years (range: 19-85 years) with histopathologically confirmed NBNC-HCC were randomly selected from our institution's database as a control group. The CEUS characteristics of the two groups were compared.

On conventional ultrasound, significant differences in tumor diameter were found between HEAML (4.0±2.0 [SD] cm; range: 1.3–8.9cm) and NBNC-HCC (8.4±4.4 [SD] cm; range: 1.6-18cm) (P<0.001) as well as in degrees of enhancement during the portal (P=0.001) and late phases (P=0.003), contrast distribution (P<0.001) and absence of pseudocaspule (P<0.001). On CEUS, hyperenhancement during the arterial phase was observed in 21/22 (95.5%) HEAMLs and in 43/44 (97.7%) NBNC-HCCs (P>0.999). Homogeneous enhancement was more frequent in HEAMLs (20/22; 90.9%) than in NBNC-HCCs (13/44; 29.6%) (P<0.001). Pseudocapsule was observed in 0/22 HEAMLs (0.0%) and in 36/44 NBNC-HCCs (81.8%) (P=0.017). A prolonged enhancement was observed in 5/22 HEAMLs (22.7%) and in 0/44 NBNC-HCCs (0.0%) (P<0.001) during the late phase.

CEUS with sulphur hexafluoride microbubbles is helpful in discriminating between HEAML and NBNC-HCC. Homogeneous enhancement and lack of pseudocapsule are suggestive features for the diagnosis of HEAML.