Retroperitoneal fibrosis (RPF) is a rare, chronic inflammatory disorder characterized by the abnormal growth of dense, scar-like tissue in the abdomen. This progressive condition, sometimes called Ormond’s disease, is immune-mediated, meaning the body’s own immune system causes the inflammation and subsequent scarring. RPF is a serious health concern due to its tendency to compress surrounding structures.
Anatomy and Pathology of Retroperitoneal Fibrosis
The condition develops in the retroperitoneum, the anatomical space situated behind the abdominal lining, called the peritoneum. This space houses the kidneys, the ureters (tubes carrying urine from the kidneys to the bladder), and major blood vessels like the abdominal aorta and the inferior vena cava. The pathology involves an inflammatory reaction leading to excessive fibrosis, forming a dense plaque or mass typically centered around the lower abdominal aorta and iliac arteries. This fibrotic mass physically encases and compresses nearby structures. The most significant danger is the compression of the ureters. When the ureters are squeezed shut, urine flow is blocked and backs up into the kidneys. This obstruction causes hydronephrosis (kidney swelling) and, if untreated, can result in kidney failure.
Recognizing the Clinical Signs
The symptoms associated with RPF are often non-specific, frequently delaying the initial diagnosis. The most common complaint is a dull, poorly localized pain, present in over 90% of patients. This discomfort is typically felt in the flank, lower back, or abdomen; male patients may also experience scrotal pain. Due to the chronic inflammatory nature of RPF, patients often experience systemic symptoms, including unexplained weight loss, low-grade fevers, and fatigue. Progressive ureteral compression leads to urinary obstruction. As the obstruction worsens, symptoms related to kidney impairment, such as azotemia or decreased urine output, may develop. Compression of major blood vessels, especially the inferior vena cava, can cause lower limb swelling (edema) or an increased risk of blood clots. High blood pressure may also occur.
Identifying the Underlying Causes
Retroperitoneal fibrosis is broadly categorized into two types based on its origin. The majority of cases, estimated to be around 70%, are classified as idiopathic RPF, meaning the cause is unknown. This idiopathic form is believed to have an autoimmune component. A significant portion of these idiopathic cases are now recognized as part of Immunoglobulin G4 (IgG4)-related disease, a systemic fibro-inflammatory disorder. The remaining 30% of RPF cases are secondary, linked to an identifiable underlying factor.
Secondary Causes
Certain medications have been strongly implicated, particularly ergot alkaloids, as well as some beta-blockers and analgesics. The condition has also been associated with malignancies, with lymphomas being the most common cancer linked to RPF. Other secondary causes include prior abdominal trauma or surgery, infections like tuberculosis, and environmental factors. Occupational exposure to asbestos and heavy tobacco smoking are recognized risk factors. Establishing the correct cause is important because the management approach for secondary RPF often involves treating the underlying condition.
Diagnosis and Treatment Options
Diagnosing RPF requires a high level of clinical suspicion due to the vague nature of the initial symptoms. Initial laboratory tests often reveal elevated inflammatory markers, such as the Erythrocyte Sedimentation Rate (ESR) and C-reactive protein (CRP), which indicate chronic inflammation. Blood tests are also performed to assess kidney function, looking for signs of impairment caused by ureteral obstruction.
Diagnosis
Imaging studies are necessary to visualize the fibrous mass and confirm the diagnosis. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) scans of the abdomen and pelvis are the preferred methods. These scans clearly show the extent of the fibrous plaque and the degree to which it is compressing the ureters and other structures. A tissue biopsy of the mass may be required in some cases to rule out malignancy, as cancerous growths can sometimes mimic RPF on imaging.
Treatment
Treatment focuses on two primary goals: relieving the compression on the ureters and reducing the underlying inflammation. To urgently address the ureteral obstruction, a procedure called stenting may be performed, where a thin tube is inserted to hold the ureter open and allow urine to drain. This decompression is often done as an initial step to protect the kidneys from irreversible damage. Medical management centers on anti-inflammatory and immunosuppressive therapy to shrink the fibrous mass. High-dose corticosteroids are the standard first-line treatment to rapidly reduce inflammation. For long-term control or in cases where steroids are not sufficient, other immunosuppressive drugs like tamoxifen, azathioprine, or mycophenolate mofetil may be used. If medical therapy fails to resolve the obstruction, a surgical procedure called ureterolysis may be necessary to physically free the ureters from the surrounding fibrous plaque.