Malignant epithelioid renal angiomyolipoma involving the inferior vena cava in a patient with tuberous sclerosis.

Renal angiomyolipomas (AMLs) are mesenchymal tumors that occur either sporadically or are associated with tuberous sclerosis, and are generally considered to be benign. Malignant AML is extremely rare, and most are found to be epithelioid histopathologically. The authors report the case of a patient followed for renal AML. On CT surveillance, this lesion developed features of a malignant tumor involving the renal vein and inferior vena cava. The patient was treated by nephrectomy and tumor thrombectomy with retroperitoneal lymph node dissection. Histological examination demonstrated renal AML with a malignant epithelioid contingent. The various aspects of this histological and radiological variant are discussed.