Contrast-enhanced ultrasonography in hepatic angiomyolipoma

Angiomyolipoma (AML) is a benign tumor of mesenchymal origin rarely found in the liver. It is composed of a variable mixture of 3 tissue components, including blood vessels, smooth muscle, and adipose cells. The imaging appearances of hepatic AML are quite variable and may overlap with those of other benign and malignant fat-containing hepatic lesions, including hepatocellular carcinoma (HCC) with fatty metamorphosis, lipoma, liposarcoma, and myelolipoma. Preoperative diagnosis of hepatic AML is still challenging. The findings of hepatic AML with computed tomography (CT) and magnetic resonance imaging (MRI) are well known. A density of less than 20 Hounsfield units on CT indicates the presence of fat in hepatic AML. High signal intensity in both T1- and T2-weighted images and a decrease in MRI signal intensity due to fat suppression also indicate fat. Early and prolonged enhancement on CT and MRI also shows the hypervascular nature of hepatic AML. To our knowledge, there are few reports describing the features of AML with color or power Doppler ultrasonography and contrast-enhanced ultrasonography (CEUS). We describe power Doppler ultrasonographic and CEUS findings in a case of hepatic AML. We also discuss the usefulness of CEUS in the differential diagnosis of fat-containing tumors of the liver.