A case of renal angiomyolipoma with intracardiac extension and asymptomatic pulmonary embolism.

Angiomyolipoma (AML) is the most common benign tumor of the kidney, which is composed of a mixture of three tissue components: blood vessels, smooth muscle and adipose cells. Occasionally, AML may extend into the renal vein or the vena cava, but so far at least, intracardiac extension was rarely reported. We herein present one case of renal AML with intracardiac extension and pulmonary embolism simultaneously in a 52-year-old Chinese female patient. Contrast-enhanced computed tomography revealed a well-demarcated heterogeneous mass in the right kidney which extended into the right atrium through the right renal vein and inferior vena cava and resulted in embolization in the right pulmonary artery. The renal mass together with the thrombus was resected. The renal mass and thrombus in vena cava and right atrium shared the similar histological features: mature adipose tissue, smooth muscle and thick-walled vessels. The thrombus in the right pulmonary artery was mainly composed of mature adipose tissue. These histological features and the result of positive immunostaining for HMB-45, Melan-A, and smooth muscle actin supported the diagnosis of AML. The component of epithelioid cells was less than 5% and mitosis was rarely seen. Intracardiac extension is often observed in the malignant tumor and only seldom seen in benign tumors. Our case reminds the rare possibility of intracardiac extension in renal AML, which may potentially result in fatal complications if not appropriately managed.