Typical case of retroperitoneal fibrosis. This was confirmed with CT-guided biopsy which demonstrated “fibroadipose tissue with fibroblasic/myofibroblasic proliferation, fibrosis and mixed chronic inflammation including plasma cells consistent with RPF; not sufficient for igG4-related.”

RPF usually starts around L4-L5 at the bifurcation and ascends, medializing and obstructing the ureters. While retroperitoneal lymphoma is a consideration, it typical “lifts” the aorta and displaces the ureters, NOT medializes them toward the mass.