Incidental renal angiomyolipoma as a cause of thrombosis of the renal vein and inferior vena cava

Angiomyolipoma (AML) is the most common benign mesenchymal tumor of the kidney. It normally has a variable number of blood vessels, smooth muscle, and adipose tissue, and is usually an incidental finding. Some of its rare complications are the invasion of the lymph nodes, vascular dissemination through the inferior vena cava, and, even more exceptionally, the development of fat embolism. We present two cases with vascular dissemination through the renal vein extending to the inferior vena cava, one of them with associated fat embolism. Vascular dissemination and fat embolism are rare but known complications of AMLs; once they appear, the treatment will always be surgical, even if the patient is completely asymptomatic.