Preoperative radiological characterization of hepatic angiomyolipoma using magnetic resonance imaging and contrast-enhanced ultrasonography: a case report

A 43-year-old Caucasian man was found to have a large echogenic mass in his right liver lobe by abdominal ultrasonography. The hepatic lesion measured about 5 × 9 cm with a well-demarcated border (Figure 1A). Color Doppler imaging showed intense vascularization in the periphery of the tumor (Figure 1B). Five months prior to admission, our patient had noticed chronic fatigue, a loss of efficiency and abdominal stress under his right costal arch. A physical examination was unremarkable. Serum biochemistry tests were without any pathological findings. The serologic assay for viral hepatitis B and C were negative. The serum alpha-fetoprotein level was 1.5 ng/mL (normal range < 6 ng/mL). Magnetic resonance imaging (MRI; 1.5T Magnetom Avanto, Siemens Medical Solutions, Erlangen, Germany) of the liver mass using a native fat-suppressed T1-weighted gradient echo sequence showed a fat-equivalent signal behavior comparable to that of the subcutaneous adipose tissue (Figure 1C). A contrast-enhanced ultrasonography (CEUS; Acuson Sequoia, Siemens Medical Solutions) was performed for further information. It revealed a well-demarcated hyperechoic liver mass in segment VI, measuring 9.7 × 9.2 × 5.4 cm in maximum diameter with a hypoechogenic portion. The margin was well defined and smooth. The contrast agent (SonoVue, Bracco International, Amsterdam, Netherlands) showed a hyperperfusion from the early to the late vascular phase in comparison with the surrounding liver tissue. There was no sign of "halo" or "nodule-in-nodule" formation (Figure 1D).

After presenting all imaging results in an interdisciplinary liver conference, an atypical resection of the right lobe of his liver was recommended. Our patient underwent surgery without any problems. After nine days, he left the hospital in good clinical condition. The macroscopic examination revealed a solitary tumor with a mottled yellow color and a soft consistency in the right lobe of his liver (Figure 1E). The microscopic examination showed that the tumor was well circumscribed but non-encapsulated and consisted mostly of adipose tissue with solid areas of elongated and rounded epithelioid cells, often arranged around thick-walled blood vessels (Figure 1F and 1G). In the solid areas, the cells expressed smooth muscle actin and the melanoma marker HMB-45 (Figure 1H). Extramedullary hematopoiesis was not observed. A diagnosis of hepatic angiomyolipoma was made. Six months after surgery our patient is in good clinical condition. Chronic fatigue and loss of efficiency have disappeared. Abdominal ultrasonography and serum biochemistry tests were without any pathological findings.