Retroperitoneal Fibrosis
	l Most commonly idiopathic l Other causes: aortic hemorrhage, aortitis, methysergide toxicity, prior surgery or XRT, collagen vascular disease (Riedel’s thyroiditis, sclerosing mediastinitis) l Clinical: 40-60 yrs, males>females l Hydronephrosis, ureteral narrowing, slight medial ureteral displacement