Idiopathic retroperitoneal fibrosis

Idiopathic retroperitoneal fibrosis (IRF) is a subtype of retroperitoneal fibrosis where no obvious cause is found. It includes a spectrum of diseases which are characterized by fibroinflammatory tissue encasing the abdominal aorta and the iliac arteries. This process may extend into the retroperitoneum often enveloping the surroundingadjacent structures e.g. ureters. 

Epidemiology

Retroperitoneal fibrosis in general is an uncommon condition with an estimated incidence of about 1.38 cases per 100,000 people ¹; of these ~70% cases are idiopathic.

Pathology

This inflammatory pathology is thought to arise as an autoimmune response to ceroid which leaks out of the atherosclerotic plaques and causes vasculitis. It is seen in association with other autoimmune processes, suggesting the possibility of an underlying autoimmune pathology.

Associations

Reported associations include

• primary biliary cirrhosis
• fibrosing mediastinitis
• glomerulonephritis
• panhypopituitarism
• rheumatoid arthritis
• ankylosing spondylitis
• polyarteritis nodosa
• systemic lupus erythematosus (SLE)
• Hashimoto thyroiditis 

Radiographic features

Contrast enhancing-enhancing fibrosis encompassing the retroperitoneal structures causing ureteric and vascular obstruction and displacement is seen with no other demonstrable alternative conditions or malignancy.

Management and prognosis

Complications such as acute renal failure secondary to periureteral involvement require prompt intervention. Treatment usually involves corticosteroids with or without other immunomodulating medications or tamoxifen. In the presence of periureteral or perivascular involvement, surgical intervention may be necessary.