What is the difference in treatment between malignant and benign retroperitoneal fibrosis?

Treatment Differences Between Malignant and Benign Retroperitoneal Fibrosis

The fundamental treatment difference is that benign retroperitoneal fibrosis (RPF) is primarily managed with immunosuppression and urinary drainage, while malignant RPF requires oncologic surgical resection with consideration of neoadjuvant radiotherapy and systemic chemotherapy. 1, 2

Critical Initial Distinction

The most important diagnostic challenge is differentiating benign from malignant RPF, as malignant RPF (accounting for up to 10% of cases) has a dismal prognosis compared to the good prognosis of benign forms. 3, 4

Diagnostic Approach

• Biopsy is mandatory to definitively distinguish malignant from benign RPF, as imaging alone (CT or MRI) cannot reliably differentiate between the two entities. 1, 2
• Image-guided core needle biopsy is preferred over open surgical biopsy to establish diagnosis and histologic subtype. 1
• The differential diagnosis must exclude lymphoma and germ cell tumors, which would require completely different treatment approaches—avoid inappropriate major resection of chemotherapy-sensitive tumors. 1, 5

Treatment of Benign (Idiopathic) Retroperitoneal Fibrosis

Initial Management

• Percutaneous nephrostomy placement is the treatment of choice for initial urinary drainage in patients with ureteral obstruction. 6, 7
• Internal ureteral stenting can be used, though its long-term efficacy is questionable. 2

Medical Therapy

• Long-term immunosuppression with corticosteroids (alone or combined with other immunosuppressants) represents the primary medical treatment. 6, 2
• Medical therapy is often combined with surgical intervention for optimal outcomes. 4

Surgical Management

• Open ureterolysis with omental flap wrapping remains the gold standard surgical treatment for severe cases with persistent ureteral obstruction. 7, 2
• Ureteral reimplantation is an alternative surgical option. 7
• Surgery is reserved for severe cases or when medical therapy fails—the purpose is to resolve ureteral obstruction, not to treat the fibrosis itself. 2
• Laparoscopic and robotic approaches are feasible in selected cases but lack comparative trial data. 2

Treatment of Malignant Retroperitoneal Fibrosis

Oncologic Surgical Approach

• Complete surgical resection with negative margins is the only curative treatment and must be performed at primary presentation by surgeons with sarcoma expertise. 1, 8
• The surgical extent depends on histologic subtype:
  • Liposarcomas: Extended resection including adjacent viscera (ipsilateral nephrectomy, hemicolectomy, psoas fascia/muscle resection, distal pancreatectomy/splenectomy) to minimize microscopic positive margins due to poorly defined borders. 1, 8
  • Leiomyosarcomas: Complete tumor resection with involved organs only, preserving uninvolved adjacent organs, as extended resections do not improve outcomes (dictated by metastatic disease risk). 1, 8

Radiation Therapy

• Neoadjuvant radiotherapy (45-50 Gy) is often preferred as it reduces tumor seeding risk and may improve resectability. 1, 8
• Adjuvant radiotherapy has limited value after complete resection and carries significant toxicity—discouraged except in highly selected cases where local recurrence would cause undue morbidity. 1, 8

Systemic Therapy

• Neoadjuvant chemotherapy may be considered when response would facilitate resection or improve symptoms. 1
• Histology-specific targeted therapies should be considered for appropriate subtypes. 1

Follow-Up Differences

Benign RPF

• Follow-up focuses on renal function tests, intravenous urography, and CT imaging to monitor for re-obstruction. 7, 2
• Ultrasonography and CT are valuable monitoring methods. 6

Malignant RPF

• Cross-sectional imaging at 3-6 month intervals initially, extending to annual after 5 years to detect asymptomatic recurrences. 1, 8
• Initial observation of image-detected recurrences may be appropriate to assess behavior before intervention. 1

Critical Pitfall

Never proceed with major surgical resection before establishing the diagnosis with biopsy—this prevents inappropriate resection of lymphoma, germ cell tumors, or benign inflammatory conditions that require medical rather than surgical management. 1, 5