Correct answer to Q1 is: Angiomyolipoma

Discussion

The patient later underwent laparoscopic lateral segmentectomy for this tumor, and pathological analyses revealed the tumor to be an angiomyolipoma.

Typical ultrasound findings of hepatic angiomyolipoma are homogeneous and strong hyperechogenicity in most cases (1). Therefore, angiomyolipoma should be included in the differential diagnosis of hyperechoic hepatic tumors. Contrast-enhanced ultrasound findings show hyperenhancement in the arterial phase, and contrast defect in the post-vascular phase, which may resemble hypervascular malignancies such as hepatocellular carcinoma (2). Angiomyolipoma can be isoechoic during the late phase, which may be a differential point from hepatocellular carcinoma, which often exhibit late-phase washout. Early draining vein shown in image B is also an important differential point from other hyperechoic hepatic tumors, which will be discussed later.

Correct answer to Q2 is: Fat-deficient angiomyolipoma

Additional discussion

Three-phase CT findings of hepatic angiomyolipoma show arterial hyperenhancement and delayed washout. Therefore it is difficult to differentiate angiomyolipoma from hypervascular malignancies such as hepatocellular carcinoma, especially when it is fat-deficient and the patient has chronic liver disease. Some additional CT findings are helpful and can be summarized as central and peripheral distribution of tortuous vascularity and early draining vein connected with the portal vein and hepatic vein (3).

Conclusion

As mentioned above, detailed knowledge on ultrasound and CT findings of hepatic angiomyolipoma are important in the differentiantion from hyperechoic and hypervascular hepatic tumors, especially from hepatocellular carcinoma.

Conflicts of Interest:

No conflict of interest.

References

1. Dietrich CF, Nolsoe CP, et al. Guidelines and good clinical practice recommendations for contrast-enhanced ultrasound (CEUS) in the liver – update 2020 WFUMB in cooperation with EFSUMB, AFSUMB, AIUM, and FLAUS. Ultrasound Med Biol. 2020;46(10):2579-2604.
2. Lee JY, Minami Y, et al. The AFSUMB consensus statements and recommendations for the clinical practice of contrast-enhanced ultrasound using Sonazoid. Ultrasonography. 2020;39:191-220.
3. Jeon TY, Kim SH, et al. Assessment of triple-phase CT findings for the differentiation of fat-deficient hepatic angiomyolipoma from hepatocellular carcinoma in non-cirrhotic liver. Eur J Radiol. 2010;73(3):601-606.