What is a key feature of retroperitoneal fibrosis when it comes to displacement of the ureters?
Although one might expect a mass to occupy space and therefore cause the ureters to displace laterally, fibrotic traction actually causes them to displace medially.
What observation can differentiate retroperitoneal fibrosis from lymphoma?
The non-displacement of the aorta is more suggestive of retroperitoneal fibrosis, whereas anterior displacement - or any displacement in general - of the aorta would favour lymphoma.
Contrast administered using the bilateral nephrostomy catheters (no intravenous contrast due to impaired renal function). Retropertineal mass surrounding, but not displacing, the abdominal aorta and part of the inferior vena cava with possible medialisation of the ureters due to fibrotic traction. At the location of the mass there is ureteral stenosis on the right and occlusion of the left ureter.