Renal Angiomyolipoma Embolization

Background and indications

Renal angiomyolipoma (AML) is a benign tumor composed of blood vessels, smooth muscle, and fat. It can be sporadic (80%) or associated with tuberous sclerosis complex (TSC, 20%). The main risk is retroperitoneal hemorrhage from intratumoral microaneurysm rupture.

Selective arterial embolization is the first-line treatment for renal AMLs ≥ 4 cm (significant hemorrhagic risk), symptomatic AMLs (pain, hemorrhage), and AMLs in women of childbearing age. It preserves renal parenchyma while reducing bleeding risk.

Pre-procedure assessment

Assessment includes renal CT or MRI (fat component confirmation, size measurement, microaneurysm identification), renal function panel (creatinine, GFR), and tuberous sclerosis screening (if multiple or bilateral AMLs). MRI differentiates fat-rich from fat-poor AMLs (which can mimic renal carcinoma).

Procedure

Under local anesthesia and sedation, a catheter is introduced through the femoral artery. Under fluoroscopic guidance, renal arteries feeding the AML are selectively catheterized. Embolization is performed with calibrated particles (100-500 µm), sometimes supplemented by coils for large feeding vessels. The goal is tumor devascularization while preserving maximum healthy renal parenchyma. The procedure takes 1 to 2 hours.

Results and scientific evidence

Selective embolization achieves 40-60% tumor volume reduction at 6-12 months and eliminates hemorrhagic risk in 90-95% of cases. Long-term reintervention rate is 15-20% (mainly in TSC where AMLs are multiple). Renal function preservation is superior to partial nephrectomy (Ramon et al., Journal of Urology, 2009; DOI: 10.1016/j.juro.2009.02.057).

Risks and complications

Post-embolization syndrome (pain, fever: 30-50%, resolving in 3-5 days), limited renal infarction (5-10%, usually without functional consequence), abscess (< 2%). Major complications are rare (< 3%).

Recovery

1-2 night hospitalization. Control CT or MRI at 3-6 months. Long-term follow-up for TSC (recurrence possible).

Practical information

The procedure is performed as a short inpatient stay or outpatient depending on the case. It is performed by an interventional radiologist, in coordination with the urologist and nephrologist.