Aims: To report the outcomes of elective and emergency embolization of renal angiomyolipoma and describe an angiographic sign that will help localize the symptomatic aneurysm in emergency cases.
Materials and methods: A retrospective review of all patients undergoing embolization of renal angiomyolipoma at a two centres between 1998-2007. Indications for treatment and angiographic images were reviewed. Incidence of acute rupture during embolization was noted.
Results: Seventeen patients underwent 23 episodes of embolization using polyvinyl alcohol (PVA) particles, bead block, and coils. Thirteen were elective procedures for large or symptomatic angiomyolipoma and 10 were acute procedures for patients presenting with retroperitoneal haemorrhage. Patients presenting acutely with haemorrhage tended to have extensive multifocal renal involvement. Active bleeding on diagnostic angiography was seen in a single patient who presented with retroperitoneal haemorrhage 48h after elective embolization with PVA alone. Seven out of 10 (70%) of the acute cases displayed splaying of adjacent vessels due to peri-aneurysmal haematoma, known locally as the "light bulb sign". This allowed treatment to be focused on the symptomatic aneurysm. The light bulb sign was not present in any patient undergoing elective embolization. Aneurysm rupture with active extravasation occurred following embolization of the distal tumour circulation with PVA in four of 10 (40%) of the patients in the acute group and three of 13 (23%) patients in the elective group. Five patients required a subsequent embolization, three at a different site. Two patients in the elective group required repeat embolization of the target site, one for delayed haemorrhage and the other whose tumour did not shrink following the initial incomplete treatment.
Conclusions: Embolization of renal angiomyolipoma produces durable results. The presence of the light bulb sign is a strong indicator of the site of haemorrhage within the kidney. We advocate using a combination of particulate material and coils, as embolization with PVA alone may predispose to acute haemorrhage occurring during or after embolization.