Fig. 1

A liver mass discovered during physical examination in a 30-year-old male patient without chronic hepatitis B. The mass is estimated to measure approximately 4.6 cm × 3.6 cm and is located in the caudate lobe (a). On contrast-enhanced ultrasonography, the mass displays hyperenhancement after the injection of the contrast agent (b), contrast agent wash-out can be observed as a hypoenhancement at the center of the lesion, and the peripheral hyperechoic area remains hyperenhancing during the portal venous phase (c) and hypoenhancing during the Kupffer phase (d)