Retroperitoneal Fibrosis (RPF)
Summary
Retroperitoneal Fibrosis (RPF), also known as Ormond's Disease, is a rare condition characterised by the Development of Fibro-inflammatory Tissue in the Retroperitoneum, typically surrounding the Abdominal Aorta and Iliac Vessels and often Encasing the Ureters, leading to Ureteric Obstruction and Hydronephrosis. RPF is classified as Idiopathic (Primary) (~70%) or Secondary (~30%), with secondary causes including Malignancy, Medications (Ergot Derivatives, Methysergide), Infections, Radiotherapy, and Aortic Aneurysm. A significant proportion of idiopathic RPF is now recognised as part of the IgG4-Related Disease (IgG4-RD) spectrum. Patients typically present with Dull Back or Flank Pain, Constitutional Symptoms, and Renal Impairment from bilateral ureteric obstruction. Diagnosis involves CT or MRI Imaging (Peri-aortic soft tissue mass) and exclusion of malignancy (Often requires Biopsy). Treatment involves Corticosteroids (First-line for idiopathic/IgG4-RD), Ureteric Stenting or Nephrostomy to relieve obstruction, and Ureterolysis (Surgical freeing of ureters) in refractory cases. [1,2,3]
Clinical Pearls
"Peri-Aortic Mass Encasing Ureters": Classic imaging finding. CT shows soft tissue surrounding aorta and enveloping ureters.
"Exclude Malignancy": Biopsy often needed. Lymphoma, Retroperitoneal sarcoma, Metastatic disease can mimic.
"IgG4-Related Disease": Many cases of idiopathic RPF are now considered IgG4-RD. Check serum IgG4.
"Steroids Work Well": First-line for idiopathic. Dramatic response common.
Demographics
| Factor | Notes |
|---|---|
| Incidence | Rare. ~0.1-1.3 per 100,000 per year. |
| Age | Peak 50-60 years. |
| Sex | Male > Female (2-3:1). |
Classification
| Type | Proportion | Causes |
|---|---|---|
| Idiopathic (Primary) | ~70% | Unknown. Many now linked to IgG4-Related Disease. |
| Secondary | ~30% | Malignancy (Lymphoma, Sarcoma, Mets). Medications (Ergot derivatives, Methysergide, Dopamine agonists). Aortic aneurysm (Inflammatory AAA). Infections (TB). Radiotherapy. Prior surgery. Asbestosis. |
Idiopathic RPF / IgG4-RD
- Autoimmune/Inflammatory Process: Fibro-inflammatory tissue develops around the aorta.
- IgG4-Related Disease: Subset characterised by elevated Serum IgG4, Tissue Infiltration by IgG4+ Plasma Cells, Storiform Fibrosis, And Obliterative Phlebitis.
- Periaortic Plaque Theory: Reaction to atherosclerotic plaque antigens (Ceroid, Oxidised LDL).
Anatomical Distribution
- Typically arises around Infrarenal Aorta and Iliac Vessels.
- Extends laterally to Encase Ureters (Usually at L4-L5 level where ureters cross pelvic brim).
- May involve IVC, Renal vessels, Mesenteric vessels.
Consequences
- Ureteric Obstruction: Bilateral (Often). Leads to Hydronephrosis, Renal impairment.
- Vascular Involvement: Aortic encasement, IVC compression (Lower limb oedema), Renal artery stenosis.
Symptoms
| Symptom | Notes |
|---|---|
| Dull Lower Back / Flank Pain | Most common (~80%). Non-colicky. Constant. |
| Abdominal Pain | |
| Constitutional Symptoms | Weight loss, Fatigue, Malaise, Low-grade fever. |
| Symptoms of Ureteric Obstruction | Oliguria/Anuria (Bilateral obstruction). Uraemia symptoms. |
| Lower Limb Oedema | IVC compression. |
| Testicular Pain | Gonadal vein involvement. |
Examination Findings
| Finding | Notes |
|---|---|
| Often Unremarkable | |
| Hypertension | Renal artery involvement. |
| Lower Limb Oedema | |
| Reduced Urine Output | If bilateral obstruction. |
| Signs of Uraemia | If renal failure advanced. |
Laboratory
| Test | Findings |
|---|---|
| U&Es / Creatinine | Elevated (Renal impairment). |
| Inflammatory Markers (ESR, CRP) | Elevated in active disease. |
| FBC | Normocytic anaemia (Chronic disease). |
| LFTs | Usually normal. |
| Serum IgG4 | Elevated in ~50-70% of IgG4-RD cases. Not specific. |
| ANA, RF | Exclude other autoimmune conditions. |
| Urinalysis | Bland (No active sediment). |
Imaging
| Modality | Findings |
|---|---|
| CT Abdomen/Pelvis (With IV Contrast) | First-Line. Peri-aortic / Peri-iliac soft tissue mass. Medial deviation of ureters (Classic). Hydronephrosis. Delayed contrast enhancement of fibrotic tissue. |
| MRI Abdomen | Better soft tissue delineation. Useful if CT contraindicated or for monitoring. |
| Ultrasound | May show Hydronephrosis. Less sensitive for mass. |
| PET-CT | Assesses disease activity (FDG avid). Useful for differentiating active inflammation from fibrosis. Excludes occult malignancy. |
Biopsy
| Notes |
|---|
| Often Required: To exclude malignancy (Lymphoma, Sarcoma, Metastases). |
| CT-Guided or Laparoscopic |
| Histology: Dense collagenous tissue. Lymphoplasmacytic infiltrate. IgG4+ plasma cells (In IgG4-RD). Storiform fibrosis. |
Management Algorithm
SUSPECTED RETROPERITONEAL FIBROSIS
(Back/Flank pain, Renal impairment, CT showing peri-aortic mass)
↓
CONFIRM DIAGNOSIS
- CT/MRI Imaging
- Exclude malignancy (Biopsy often needed)
- Inflammatory markers (ESR, CRP)
- Serum IgG4
↓
ASSESS URETERIC OBSTRUCTION
- Renal function (U&Es)
- Hydronephrosis on imaging
┌────────────────┴────────────────┐
SIGNIFICANT OBSTRUCTION / NO SIGNIFICANT OBSTRUCTION
RENAL IMPAIRMENT
↓ ↓
**DRAINAGE (URGENT)** **MEDICAL THERAPY**
- Ureteric Stent (Retrograde) or
- Percutaneous Nephrostomy
↓
MEDICAL THERAPY (IDIOPATHIC / IgG4-RD)
┌──────────────────────────────────────────────────────────┐
│ **FIRST-LINE: CORTICOSTEROIDS** │
│ - Prednisolone 30-60 mg/day (0.5-1 mg/kg) │
│ - Taper over 6-12 months │
│ - Dramatic response in most idiopathic/IgG4-RD cases │
│ - Monitor: ESR/CRP, Renal function, Imaging │
│ │
│ **STEROID-SPARING / REFRACTORY (Second-Line)** │
│ - Tamoxifen (Anti-fibrotic, Anti-oestrogenic) │
│ - Mycophenolate Mofetil │
│ - Methotrexate │
│ - Azathioprine │
│ - Rituximab (For IgG4-RD) │
└──────────────────────────────────────────────────────────┘
↓
SURGICAL THERAPY
┌──────────────────────────────────────────────────────────┐
│ **URETEROLYSIS** │
│ - Surgical freeing of ureters from fibrotic tissue │
│ - + Intraperitonealisation (Wrapping ureters in omentum │
│ to prevent re-encasement) │
│ - Indicated: Failed medical therapy, Severe/Recurrent │
│ obstruction, Malignancy excluded │
│ │
│ **OPEN or LAPAROSCOPIC** │
└──────────────────────────────────────────────────────────┘
↓
SECONDARY RPF
- Treat underlying cause (Malignancy, Infection)
- Discontinue causative medication
- May still need drainage and medical/Surgical therapy
↓
MONITORING
- Regular inflammatory markers
- Renal function
- Imaging (CT/MRI) at intervals
- Long-term follow-up (Relapse common on steroid tapering)
Tamoxifen
| Notes |
|---|
| Anti-fibrotic effects. Reduces TGF-β. |
| Used as steroid-sparing agent or adjunct. |
| Dose: 20 mg BD. |
| Well-tolerated. Monitor for VTE. |
| Complication | Notes |
|---|---|
| Chronic Kidney Disease / ESRD | From prolonged obstruction. |
| Acute Kidney Injury | Bilateral obstruction. |
| Hypertension | Renal artery involvement. |
| Lower Limb DVT | IVC compression. |
| Aortic Aneurysm | May be associated (Inflammatory AAA). |
| Relapse | Common on steroid tapering. May need long-term therapy. |
| Steroid Side Effects | With prolonged use. |
| Factor | Notes |
|---|---|
| Response to Steroids | Excellent in idiopathic/IgG4-RD (~90% improvement). |
| Renal Function Recovery | Good if treatment initiated before irreversible damage. |
| Relapse Rate | ~20-50% on steroid tapering. May need maintenance/Steroid-sparing agent. |
| Mortality | Low with treatment. |
| Secondary RPF | Prognosis depends on underlying cause (Poorer if malignant). |
Key Guidelines
| Guideline | Notes |
|---|---|
| No formal consensus guidelines | Management based on case series and expert opinion. |
| IgG4-RD Guidance | Corticosteroids first-line. Rituximab for refractory. |
What is Retroperitoneal Fibrosis?
RPF is a rare condition where scar-like tissue develops in the back of the abdomen (Retroperitoneum). This tissue can wrap around the tubes that drain urine from the kidneys (Ureters), Blocking them and causing kidney problems.
What are the symptoms?
- Dull, Aching pain in the lower back or sides.
- Feeling tired, Weight loss.
- Reduced urine output (If both ureters blocked).
- Swelling in the legs.
What causes it?
In most cases, The exact cause is unknown ("Idiopathic"). It may be linked to an overactive immune system. Sometimes it is caused by certain medications, Cancers, Or infections.
How is it diagnosed?
- CT or MRI scan: Shows the abnormal tissue.
- Blood tests: Check kidney function and inflammation.
- Biopsy: May be needed to rule out cancer.
How is it treated?
- Steroids (Prednisolone): First-line treatment. Works well in most cases.
- Stent or Drain: If the ureters are blocked, A tube may be placed to allow urine to drain.
- Surgery: If medication doesn't work, Surgery to free the ureters may be needed.
- Long-term Follow-Up: The condition can come back, So regular monitoring is important.
Primary Sources
- Vaglio A, et al. Retroperitoneal fibrosis. Lancet. 2006;367(9506):241-251. PMID: 16427492.
- Stone JH, et al. IgG4-related disease. N Engl J Med. 2012;366(6):539-551. PMID: 22316447.
- Scheel PJ Jr, Feeley N. Retroperitoneal fibrosis. Rheum Dis Clin North Am. 2013;39(2):365-381. PMID: 23597968.
Common Exam Questions
- Classic Imaging Finding: "What is the classic CT finding in RPF?"
- Answer: Peri-aortic soft tissue mass surrounding the infrarenal aorta and iliac vessels, Often Encasing the ureters and causing Medial deviation of ureters.
- Associated Condition: "What is RPF increasingly recognised as part of?"
- Answer: IgG4-Related Disease (IgG4-RD).
- First-Line Treatment: "What is the first-line medical treatment for idiopathic RPF?"
- Answer: Corticosteroids (e.g., Prednisolone).
- Surgical Procedure: "What surgical procedure is used for refractory ureteric obstruction in RPF?"
- Answer: Ureterolysis (With Intraperitonealisation – Wrapping ureters in omentum).
Viva Points
- Exclude Malignancy: Biopsy often needed. Lymphoma is a key differential.
- Serum IgG4: Elevated in ~50-70% of IgG4-RD related cases.
- Bilateral Hydronephrosis + Peri-Aortic Mass = RPF: Until proven otherwise.
- Inflammatory AAA: Can be associated. Check for aneurysm.
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