Imaging findings in myomatous angiomyolipoma of the liver.

Angiomyolipoma of the liver is a rare benign mesenchymal tumor, comprising three tissue components: blood vessels, smooth muscles, and adipose cells. Depending on the predominance of these components, tumors are categorized into various types, out of which the myomatous variant is the most rare. Most of these tumors are detected incidentally and are solitary when discovered. Definitive preoperative diagnosis is often difficult because the radiological appearance of hepatic angiomyolipoma can be non-specific and varied. This is because the distribution and relative proportion of the three tissue components vary widely from tumor to tumor. Here, we present ultrasonography (US), multidetector computed tomography (CT), and magnetic resonance imaging (MRI) findings with pathological correlations of myomatous angiomyolipoma of the liver in a 21-year-old asymptomatic man who had no history of liver disease, hepatitis, or tuberous sclerosis. The tumor was hypoechoic on US and showed wash-in in the arterial phase and wash-out in the portal-venous phase on both dynamic contrast-enhanced CT and MRI. Additionally, the lesion was hypointense in the hepato-biliary phase on MRI obtained two hours after gadobenate dimeglumine administration and was not clearly identified from fat tissue in the in-phase/opposed-phase T1-weighted sequences.