Retroperitoneal Fibrosis

Key Points:

Chronic Condition: Retroperitoneal fibrosis involves chronic inflammation and fibrosis around the abdominal aorta and iliac arteries, commonly extending to surrounding structures like the ureters.
Etiology:
- Idiopathic (Ormond's disease) in 70% of cases.
- 30% are associated with:
  - Drugs, notably ergot alkaloids and dopamine agonists.
  - Infections, trauma, surgeries, radiation therapy.
  - Primary or metastatic neoplasms.
- Many idiopathic cases are linked to inflammatory abdominal aortic aneurysms.
Pathophysiology:
- Considered a form of chronic periaortitis.
- Confined to central and paravertebral spaces between renal arteries and sacrum.
- Typically begins at the aortic bifurcation and extends cephalad.
- In 15% of cases, it extends outside the retroperitoneum to involve the peripancreatic and periduodenal spaces, pelvis, and mediastinum.

Associations and Manifestations:

Autoimmune Link: Idiopathic retroperitoneal fibrosis is thought to be a systemic autoimmune disease.
- Associated with HLA-DRB1*03, linked to autoimmune diseases such as:
  - Type 1 diabetes mellitus.
  - Myasthenia gravis.
  - Systemic lupus erythematosus.
- May present as part of a well-defined systemic autoimmune disorder or organ-specific autoimmune diseases, e.g., Hashimoto thyroiditis, sclerosing cholangitis.
Demographics:
- Affects men 2-3 times more often than women.
- Predominantly in the age group of 50-60 years.

Symptoms and Laboratory Findings:

Symptoms:
- Systemic symptoms like fatigue, low-grade fever, weight loss, myalgias.
- Localized symptoms may include side, back, or abdominal pain, lower extremity edema, scrotal swelling, varicocele, or hydrocele.
Laboratory Tests:
- Azotemia.
- Elevated acute-phase reactants (80-100% of patients), e.g., erythrocyte sedimentation rate, C-reactive protein.

Diagnosis and Management:

Diagnostic Imaging:
- CT scan is typically the initial step.
- MRI findings in early and mature stages of the disease.
Treatment Goals:
- Manage inflammation and fibrosis.
- Relieve ureteral obstruction.
- Address systemic inflammatory response and constitutional manifestations.
Treatment Options:
- Corticosteroids as the mainstay for idiopathic cases.
- Immunosuppressants, e.g., azathioprine, methotrexate, cyclosporine, and tamoxifen, when unresponsive to steroids.
- Operative management preferred for steroid-resistant obstructive uropathy.
- Ureterolysis with intraperitoneal transposition and omental wrapping.
- Placement of ureteral stents as a temporary measure.
- Repair of an associated abdominal aortic aneurysm if it exceeds 4.5 to 5 cm.

Comprehensive Summary: Retroperitoneal fibrosis is a potentially autoimmune-related condition primarily affecting middle-aged men. It's often idiopathic but can also be related to various drugs and medical conditions. The chronic inflammatory process starts at the aortic bifurcation and can spread to involve significant structures, leading to systemic symptoms and potential complications like ureteral obstruction. The association with specific HLA types hints at an autoimmune pathogenesis. Diagnosis is largely reliant on imaging, while treatment revolves around managing inflammation and addressing any obstruction caused. Steroids are the first line of treatment, with additional immunosuppressive therapies and surgical interventions applied as needed, particularly in steroid-resistant cases or those involving aneurysms.