Emergency embolization of actively bleeding small renal angiomyolipoma with a fast growth in four months.

Angiomyolipoma (AML) is the most common benign tumour of the kidney and is composed of smooth muscle cells, blood vessels and fat elements. AMLs are usually casually discovered when the kidneys are imaged for other reasons. Their first presentation is often a spontaneous retroperitoneal haemorrhage or bleeding into the urinary collection system, which can be life-threatening. The bleeding tendency is related to the irregular, aneurysmal, tortuous blood vessels that compose the tumor. The greatest risks for bleeding are tumour size and grade of the vascular component of the tumour. Moreover, the risk of bleeding is proportional to the size of the lesion (it is higher in AMLs with a diameter more than 4 cm). Shock due to a grave haemorrhage from AML rupture is called Wunderlich syndrome that is clinically characterized by the Lenk's triad: acute flank pain, a flank mass and hypovolemic shock.Other symptoms and signs may be present: haematuria, palpable mass, flank pain, urinary tract infections, renal failure or hypertension. Small AMLs usually require no therapy, although follow-up is recommended in order to follow its growth. Larger or symptomatic lesions can be electively embolized and/or resected with a partial nephrectomy. AMLs that present with retroperitoneal haemorrhage frequently require emergency embolization. We describe a case of an actively bleeding small renal AML, with a rapid growth, without any evidence for big aneurysmal vessels, who underwent an emergency embolization at our hospital.