Bilateral Hydronephrosis From Retroperitoneal Fibrosis

Area of Science:

• Rheumatology
• Nephrology
• Vascular Surgery

Background:

• Retroperitoneal fibrosis (RPF) is a rare condition, often idiopathic (IRF), characterized by fibroinflammatory tissue that can compress retroperitoneal structures.
• RPF is thought to be immune-mediated, frequently associated with autoimmune diseases like IgG4-related disease (IgG4-RD), and can be part of chronic aortitis syndromes, often presenting with aortic aneurysms.

Observation:

• A 63-year-old woman presented with flank pain and hydronephrosis due to a retroperitoneal mass compressing the left ureter, alongside a thoracoabdominal aneurysm.
• FDG-PET scan revealed hypermetabolism in the mass, which enlarged within four months, affecting the right ureter and requiring bilateral ureteral stents and aneurysm repair.
• Biopsy showed dense fibrosis with mononuclear infiltrate, and aneurysm histology revealed chronic periaortic inflammation. Lab tests showed elevated CRP and ESR.

Findings:

• The patient was diagnosed with idiopathic retroperitoneal fibrosis (IRF) presenting with obstructive uropathy and a thoracoabdominal aneurysm.
• Histopathological findings confirmed dense fibrosis and chronic inflammation, consistent with IRF and associated aortitis.

Implications:

• Idiopathic retroperitoneal fibrosis (IRF) requires consideration in patients with obstructive uropathy, mimicking malignancy or calculi.
• Prompt diagnosis and high-dose steroid treatment are essential for IRF management, with other immunosuppressants used for resistant cases.
• The association with aortic aneurysms highlights the need for multidisciplinary management involving rheumatology, nephrology, and vascular surgery.