In this video lecture, we focus on variants and malignant mimics of hemangioma and discuss how to characterize these masses on ultrasound, CT and MRI.
Key points include:
1) The ultrasound “target” sign is typical for hepatic metastases and appears as a lesion with a hypoechoic periphery and echogenic center.
2) Hemangiomas in a fatty liver may appear hypoechoic and mimic a more serious tumor but can be definitively characterized with MRI.
3) Sclerosed or hyalinized hemangiomas contain fibrous tissue and therefore have variable enhancement and diminished T2 hyperintensity.
4) Hemangiomas can be associated with arterioportal shunts and may be surrounded by areas of transient hepatic enhancement difference (THED) and peritumoral sparing of fatty infiltration.
5) Differential diagnostic considerations for hepatic hemangioma include hypervascular liver metastases (including melanoma and pancreatic neuroendocrine tumor), intrahepatic mass-forming cholangiocarcinoma, and hepatic angiosarcoma.
6) Irregular rim enhancement is not the same as interrupted peripheral nodular enhancement and should raise suspicion for malignancy in a solid mass.
7) Metastatic tumors may progressively fill in and mimic hemangioma, but often show less pronounced “evil grey” T2 hyperintensity isointense to spleen, restrict diffusion, and have atypical enhancement.
8) Mass-forming, peripheral intrahepatic cholangiocarcinoma can mimic hemangioma as both tumors demonstrate gradual progressive enhancement, but cholangiocarcinoma enhancement will be heterogeneous and not usually isointense to blood pool.
9) Intrahepatic cholangiocarcinoma is heterogeneously T2 hyperintense often with central hypointensity and overlying capsular retraction but may not have associated biliary ductal dilatation.
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