A Case of Life-threatening Rupture of Small Renal Angiomyolipoma with an Unidentified Intratumoral Aneurysm during Follow-up.

We report a case of a life-threatening ruptured renal angiomyolipoma (AML) that did not meet the criteria for prophylactic treatment (tumor >4 cm or intratumoral aneurysm >5 mm) during follow-up. A woman in her 70s was followed up for a 2.5-cm AML with a rich vascular component. An intratumoral aneurysm >5 mm was not identified for 2 years. She complained of a sudden abdominal pain with hypotension, and contrast-enhanced computed tomography revealed a retroperitoneal hematoma with contrast media extravasation from an intratumoral aneurysm. Emergency transcatheter arterial embolization was successfully performed using N-butyl cyanoacrylate glue. Rupture can occur in small AMLs or in AMLs not identified with intratumoral aneurysms during follow-up. AMLs with a rich vascular component at the kidney surface are more likely to rupture.