Retroperitoneal Fibrosis


Article Author:
Joshua Engelsgjerd


Article Editor:
Chad LaGrange


Editors In Chief:
Emilio Volz
Robert Jarman
Michael Lambert


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Kyle Blair
Trevor Nezwek
Radia Jamil
Erin Hughes
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Navid Mahabadi
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beata Beatty
Daniyal Ameen
Altif Muneeb
Beenish Sohail
Nazia Sadiq
Hajira Basit
Phillip Hynes
Komal Shaheen
Sandeep Sekhon


Updated:
4/7/2019 12:19:43 AM

Introduction

Retroperitoneal fibrosis (RPF) is a relatively rare condition that is characterized by a chronic inflammatory and fibrotic process in the retroperitoneum that can lead to compression of structures within the retroperitoneum. This fibrotic process can often lead to encasement of the ureters and other abdominal organs including the inferior vena cava. The process can be idiopathic or secondary to other causes. Treatment can involve medical therapy and/or surgical management.

Etiology

Approximately 70% of cases of retroperitoneal fibrosis are idiopathic. Idiopathic retroperitoneal fibrosis is considered part of the spectrum of chronic periaortitis, a large vessel vasculitis. Ceroid, a complex polymer of oxidized proteins and lipids often found in atherosclerotic plaques, has been hypothesized as an antigen that initiates the inflammatory response[1][2].

Thirty percent of retroperitoneal fibrosis cases are a result of an identifiable cause. Numerous drugs have been implicated in the development of RPF. Drugs such as methysergide (Sansert) and other ergot alkaloids are most commonly associated with this condition. Other medications that have been implicated include beta blockers, methyldopa, hydralazine, and analgesics. The biological agents etanercept and infliximab have also been identified as secondary causes. Malignancy (carcinoid, Hodgkin and non-Hodgkin lymphoma, sarcomas), infections (TB, histoplasmosis, actinomycosis), radiation therapy for testicular seminoma, colon, and pancreatic cancer, retroperitoneal hemorrhage and surgery have also been identified as secondary causes of retroperitoneal fibrosis. Studies have demonstrated exposure to asbestos, and tobacco smoke may result in increased risk of RPF[3].

Epidemiology

RPF most commonly affects patients between the ages of 40 and 60. There is a male predominance, with a male to female ratio estimated to be approximately 2:1 or 3:1. The true incidence is unknown but is estimated to be 1 per 200,000 to 500,000 per year.

Pathophysiology

Idiopathic retroperitoneal fibrosis is currently hypothesized to be a manifestation of a systemic autoimmune disease, which may arise as a primary aortitis that elicits a periaortic fibro-inflammatory response. The condition is frequently associated with increased concentrations of acute phase reactants, autoantibodies, and known autoimmune diseases. The disease also affects other vascular segments such as the thoracic aorta and mesenteric arteries, which supports the concept that it is a primary systemic inflammatory disease of large arteries. Ceroid, a complex polymer of oxidized lipids and protein found in atherosclerotic plaques, is hypothesized as being the antigen that initiates the inflammatory response. Histologically, there is the presence of macrophages, plasma cells, B and T lymphocytes. Most plasma cells are positive for immunoglobulin 4 (IgG4). The presence of IgG4-producing plasma cells suggests that RPF could also be a manifestation of IgG4-related disease (IgG4-RD). This is a multisystem disease characterized by tumor-like swelling of involved organs; lymphoplasmacytic infiltrate enriched in IgG4 positive plasma cells and variable degrees of fibrosis. The exact pathophysiology of drug-induced RPF remains unclear[3][4][5][6].

Histopathology

Pathologically, the gross appearance of RPF is that of a smooth, flat, tan-colored dense mass that encases the retroperitoneal structures, usually centered at the fourth and fifth lumbar vertebrae. It has been shown to invade the ureter or psoas muscle. Histologically, the appearance of RPF is that of a nonspecific inflammatory process. There is fibroblastic proliferation with densely hyalinized collagen, and variable chronic infiltrates composed of IgG4 positive plasma cells and lymphocytes[3].

History and Physical

The retroperitoneal fibrosis mass centers around the distal aorta between L4 and L5 and encases the ureters. This can lead to hydronephrosis via extrinsic compression on the ureters leading to interference with ureteral peristalsis. Presenting symptoms usually include lower back and/or flank pain. This pain is often described as dull, non-colicky, unchanged with position, and with radiation into the groin or lower abdomen. The pain is relieved with aspirin rather than narcotics. In 2 of the largest retrospective series looking at RPF, the pain was present upon presentation in over 90 percent of patients[2]. Testicular pain was noted in more than 50% of male patients in one randomized trial of 40 patients[7]. Other possible associated symptoms include nausea, generalized malaise, anorexia, weight loss, oliguria, anuria. In retrospective studies, fatigue and substantial weight loss were present in 60% and 54% of presenting patients respectively. The inferior vena cava can also be obstructed due to extrinsic compression from the mass leading to deep venous thrombosis and lower extremity edema. Patient’s may also describe upper-leg claudication related to arterial compromise of the lower extremities, or symptoms of mesenteric ischemia due to compression of mesenteric arteries[3][8][2][9].

On physical exam, CVA tenderness to percussion is often present. Patient’s may have hypertension due to renal artery impingement. One study found hypertension present in 57% of patients on presentation. Lower extremity edema or evidence of thrombophlebitis or DVT may be present. A hydrocele may be evident on GU exam, as well as testicular tenderness.

Evaluation

Retroperitoneal fibrosis is often discovered incidentally in the workup of urinary tract obstruction or venous/arterial insufficiency. The diagnosis is often made by imaging studies, including CT imaging studies and MRIs. A definitive diagnosis requires a tissue biopsy, though it is controversial whether a biopsy is necessary for patients with imaging studies demonstrating findings characteristic of RPF.

Typically, initial evaluation of the patient a laboratory workup is obtained, as well as an initial renal ultrasound, if the patient is presenting with complaints of flank pain. Laboratory findings can be varied, and no hematologic or biochemical abnormality is specific to RPF. Often an elevation in creatinine concentration and blood urea nitrogen is found, depending on the presence and extent of ureteral obstruction. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are elevated in one half to two-thirds of RPF patients. Anemia can also be observed, likely related to renal insufficiency and chronic inflammation. Renal ultrasound often reveals a poorly marginated, periaortic mass that is typically hypoechoic and may be associated with hydronephrosis[3].

A contrast-enhanced CT scan is the exam of choice to visualize the extent of RPF and the presence of lymphadenopathy and tumor. On non-enhanced CT, RPF exhibits the same attenuation numbers to that of the psoas muscle (1 to 25 Hounsfield units). After administration of intravenous contrast, enhancement depends on the stage of the disease. Avid enhancement is often seen in early stages of the disease, whereas in late and inactive stages of the disease, there may be little or no enhancement. The mass is typically confluent and encasing the anterior and lateral sides of the aorta, often encircling and compressing the IVC. Typical findings also include hydronephrosis and medial deviation of the proximal ureter and mid-ureter and a smoothly tapered ureter at the level of the obstruction. One benefit of CT is it enables CT-guided biopsy to obtain tissue for pathologic diagnosis[9][10][11].

MRI is considered equivalent to CT in diagnosing and monitoring RPF, but it has a higher contrast resolution. It is helpful as the mass itself has characteristic T1 and T2-weighted images. RPF is characterized by diffusely low signal intensity on T1-weighted imaging, although the T2 signal may vary considerably, with high signal intensity consistent with the active disease. With treatment, T2 signal often diminishes and provides a measure of therapeutic efficacy. Gadolinium enhancement may also be valuable in assessing response to treatment. Associated decreases in gadolinium contrast enhancement should be expected after appropriate therapy[10][2].

The role of biopsy is controversial. If surgical intervention is planned for treatment of compression of ureters and/or IVC, an open biopsy of the mass is recommended. A CT-guided biopsy can be obtained during initial workup prior to any treatment as well. Expert consensus suggests a biopsy of the mass in certain scenarios. These cases include:

  • When the location of the mass is atypical 
  • When clinical and laboratory findings suggest the presence of an underlying infection or malignancy 
  • Bulky appearance on imaging studies; extension above the origin of the renal arteries or anterior displacement of the aorta 
  • Local experience with RPF is limited
  • Lack of response to initial therapy

The pathological findings in idiopathic and secondary RPF are often indistinguishable. Microscopically, the fibrous tissue is comprised of an extracellular matrix composed of type-1 collagen fibers organized in thick irregular bundles, often encircling small vessels. The infiltrate consists of macrophages, plasma cells, B and T lymphocytes. The aggregates usually have a core rich in CD20+ B cells and periphery rich in CD3+ T cells. Most plasma cells are positive for immunoglobulin G4 (IgG4)[12].

Treatment / Management

Initial Management

Initial management of RPF depends on the patient’s clinical status. Patient’s with signs of ureteral compression with hydronephrosis and uremia require emergent decompression by either percutaneous nephrostomy tube or indwelling ureteral stents. Ureteral stent placement is usually not difficult in the setting of ureteral obstruction caused by RPF. The advantage of ureteral stent placement is the opportunity for retrograde pyelograms at time of the procedure to evaluate the anatomy. In critically ill patients with electrolyte abnormalities and little or no urine output, nephrostomy tube placement is favored.

After renal decompression, the patient must be monitored closely for post-obstructive diuresis, renal function status and appropriate replacement of fluids and electrolytes. Post-obstructive diuresis is a prominent polyuria that occurs after relieving complete obstruction of the urinary system (exceeding more than 200 mL per hour). Patients are at risk for severe dehydration, electrolyte imbalances, and hypovolemic shock. The condition usually lasts less than 48 hours. Treatment includes close monitoring of serum BUN, creatinine and electrolytes, and replacement of fluid. Oral replacement is preferred, but if the patient cannot tolerate oral liquids or is unable to keep up with the loss, one-half normal saline is used to replace half of the fluid loss (500 mL for every 1 L lost).  After initial management, it is necessary to identify the potential cause of RPF. Any potential inciting drug should be discontinued immediately.

Medical Treatment

Once a diagnosis of RPF is made, whether by radiologic findings or biopsy proven, the common primary medical management has been steroid therapy. The medical literature describes an 80% response rate when treating RPF with steroids alone. This includes resolution of pain and constitutional symptoms within days after initiation of treatment, rapid decline in ESR and diuresis. Dosages and duration of steroid therapy vary considerably, but most regimens start with an initial dose of 60 mg daily tapered to 5 mg daily. One expert consensus recommends treating with prednisone 1 mg/kg per day for approximately 4 weeks. If improvement is observed, the dose is tapered over months to 10 mg/day and maintained for an additional 6 to 18 months. Chronic steroid therapy up to 2 years has been shown to provide a significant improvement in clinical symptoms and regression of retroperitoneal mass. Failure to detect clinical or radiologic improvement within 4 to 6 weeks of initiation of therapy should prompt reevaluation with CT scan and a biopsy to determine if the diagnosis of RPF is correct. If it is confirmed that the disease is RPF, other agents can be used concurrently with steroids. These agents include azathioprine, methotrexate, mycophenolate mofetil, cyclophosphamide, and cyclosporine. Medroxyprogesterone acetate, progesterone, and tamoxifen have also been found to be beneficial in the treatment of RPF. [13][14][15] Use of immunosuppressive agents is reserved for when steroid therapy fails, as relapse rates have been documented as high as 50% during steroid tapering [16][17][18][19].

Monitoring a patient’s response to therapy requires close follow up. The patient should be evaluated clinically within 1 month of initiating treatment for resolution of pain and resolution of urinary obstruction. After that, the patient should be monitored clinically every 2 to 3 months. Clinicians should obtain ESR, CRP, serum creatinine and BUN monthly for the first three months, then every 2 to 3 months. A CT scan should be obtained one month after initiating therapy, then approximately every 3 months to follow the size of the fibrotic mass. Following discontinuation of medical therapy, it is recommended to monitor for disease relapse by obtaining a renal ultrasound, ESR, CRP, serum creatinine concentration every 3 to 6 months and CT every 6 months for the first year, then laboratory testing every 6 to 12 months and CT every 1 to 2 years. Surveillance should be continued indefinitely.

Surgical Treatment

Surgical management is reserved for the following scenarios: 

  • Technical difficulties or complications with other cystoscopic or endoscopic obstruction-relieving maneuvers
  • Lack of regression of mass after medical therapy, with persistent encasement of ureters and other structures
  • Findings to suggest underlying malignancy to obtain a definitive diagnosis

Surgical management can be approached with an open, laparoscopic, or robotic exploration and entails ureterolysis and manipulation of the ureters to prevent recurrent obstruction. Methods employed to prevent recurrent ureteral obstruction include wrapping the ureters with omental fat to serve as a barrier to prevent encasement by fibrous tissue and promote revascularization, transplantation of ureters to an intraperitoneal position, or transposition of the ureters laterally, with interposition of retroperitoneal fat between ureters and fibrous tissue[20][21][22][23].

Differential Diagnosis

Retroperitoneal Lymphoma: Retroperitoneal fibrosis is centered at the L4 to L5 level. If imaging studies show mass centered more cephalad to L4 to L5, consider possible lymphoma diagnosis.

Retroperitoneal Erdheim-Chester disease: This is a rare non-Langerhans cell, non-familial multisystemic granulomatosis, widespread manifestations and variable severity that can sometimes present with involvement of retroperitoneum and hydronephrosis. Most commonly affects the bones and presents with bone pain.

Prognosis

Often within a few days of initiating treatment the patient's symptoms begin to improve. After several weeks CT imaging may demonstrate resolution of the mass. Full resolution of all associated manifestations is dependent on the degree of severity of the disease and the degree of entrapment of retroperitoneal structures. If medical management is not effective in treating the mass, surgical therapy can effectively remove the fibrotic tissue and protect the ureters.

Pearls and Other Issues

Retroperitoneal fibrosis is a disorder that is rare and most commonly encountered during the workup of a patient with renal insufficiency being caused by ureteral compression by a retroperitoneal mass. During the initial management, it is vital to determine the severity of the patient's renal impairment and to perform a procedure to allow decompression of the collecting system to protect the kidneys. This will be dependent on the patient's overall status at the time of diagnosis. After decompression of the collecting system, it is critical to monitor for post-obstructive diuresis and replace fluids/electrolytes as necessary.

After the kidneys are protected, the next step in the workup of retroperitoneal fibrosis is to obtain a diagnosis. It is argued that if CT imaging studies are characteristic of RPF, no biopsy is necessary. In this case, the clinician can begin medical therapy with steroids and follow the regimen as outlined in the treatment section. If surgical intervention is deemed necessary, an open biopsy can be obtained at that time. There are certain scenarios when a CT-guided biopsy may be performed to aid in diagnosis and guide medical therapy. These reasons are listed above. 

Surgical management is necessary if ureteral stents and/or percutaneous nephrostomy tubes are unable to be placed, medical therapy is ineffective in the treatment of RPF. or if it is felt that there could be an underlying malignancy. This can be approached robotically, laparoscopically or open and numerous maneuvers are discussed to increase the likelihood of a surgical procedure being effective.

Enhancing Healthcare Team Outcomes

RF is a complex disorder that is best managed by a multidisciplinary team that includes a urologist, general and vascular surgeon, internist, radiologist, and pathologist. Medical therapy with steroids and other immunosuppressive is widely used and it is important that the pharmacist educate the patient on the potential adverse effects. Once treatment starts, the outcomes depend on the chronicity of the condition. While some patients do have a reversal of the fibrosis, others continue to have residual renal and ureteral impairment. Some patients may benefit from surgical decompression but unfortunately, most patients are debilitated and frail for complex surgery.


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Retroperitoneal Fibrosis - Questions

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65-year-old female presents with numerous complaints, including loss of energy over 4 years, chronic pain in the chest and abdomen, fever, weight loss, and malaise. Multiple radiological investigations are performed over the past 2 years. The latest MRI reveals severe fibrosis of the retroperitoneum and pleura. What is the drug most likely responsible for these latest findings?



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A 50-year-old male is transported to the emergency department after being found on the floor in his apartment. On arrival, he is afebrile but hypotensive and tachycardic. He is nonresponsive. According to his wife, he has no significant past medical history. She reports that he has been complaining of back pain for several weeks. Initial laboratory workup reveals a serum creatinine of 5.7 mg/dL, potassium 6.2 mmol/L, sodium 124 mmol/L, and an elevated alkaline phosphatase level. There is no urine output with Foley catheter insertion. A bedside ultrasound reveals hydronephrosis bilaterally. What is the first step necessary in the care of this patient?



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After placement of percutaneous nephrostomy tubes by interventional radiology for a patient with newly diagnosed retroperitoneal fibrosis with acute renal failure, the patient is having excellent urine output, greater than 200 mL/hr for the past 4 hours. The patient is tolerating oral intake at this time. What should the next step in management be?



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A 47-year-old male presents to his primary care doctor with complaints of bilateral flank pain, fatigue, anorexia, and slight enlargement of his left testicle with associated pain. Physical exam reveals a small hydrocele of the left testicle with tenderness to palpation, bilateral costovertebral angle tenderness to percussion and hypertension. A renal ultrasound is performed which reveals bilateral hydronephrosis and possible retroperitoneal mass. Laboratory testing reveals a serum creatinine level of 1.2 mg/dL, which is slightly elevated from the patient’s baseline. What is the most appropriate next step in the care of this patient?



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A patient was recently diagnosed with retroperitoneal fibrosis causing hydronephrosis bilaterally and mild acute kidney injury. What is the appropriate medical therapy for this patient?



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What is the best imaging modality to monitor a patient’s response to medical therapy for retroperitoneal fibrosis?



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Histologically, the appearance of retroperitoneal fibrosis is that of a chronic inflammatory process and the infiltrate consists of macrophages, B and T lymphocytes, and what other characteristic cell?



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Retroperitoneal Fibrosis - References

References

Surgical treatment of retroperitoneal fibrosis with omentoplasty., Carini M,Selli C,Rizzo M,Durval A,Costantini A,, Surgery, 1982 Feb     [PubMed]
Retroperitoneal fibrosis., Pipitone N,Vaglio A,Salvarani C,, Best practice & research. Clinical rheumatology, 2012 Aug     [PubMed]
Idiopathic retroperitoneal fibrosis treated with tamoxifen only., al-Musawi D,Mitchenere P,al-Akraa M,, British journal of urology, 1998 Sep     [PubMed]
Idiopathic retroperitoneal fibrosis. A retrospective analysis of 60 cases., Baker LR,Mallinson WJ,Gregory MC,Menzies EA,Cattell WR,Whitfield HN,Hendry WF,Wickham JE,Joekes AM,, British journal of urology, 1987 Dec     [PubMed]
Idiopathic retroperitoneal fibrosis revisited., Barbalias GA,Liatsikos EN,, International urology and nephrology, 1999     [PubMed]
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Multi-institutional survey of laparoscopic ureterolysis for retroperitoneal fibrosis., Duchene DA,Winfield HN,Cadeddu JA,Clayman RV,Gomella LG,Kavoussi LR,Mikhail AA,Park S,Permpongkosol S,Shalhav AL,, Urology, 2007 Jun     [PubMed]
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Treatment of idiopathic retroperitoneal fibrosis by immunosuppression., McDougal WS,MacDonell RC Jr,, The Journal of urology, 1991 Jan     [PubMed]
Scrotal involvement with idiopathic retroperitoneal fibrosis., Schulte-Baukloh H,Knispel HH,Dallenbach F,Miller K,, The Journal of urology, 1999 Nov     [PubMed]
University of Michigan surgical experience with ureterolysis for retroperitoneal fibrosis: a comparison of laparoscopic and open surgical approaches., Styn NR,Frauman S,Faerber GJ,Wolf JS Jr,, Urology, 2011 Feb     [PubMed]
Prednisone versus tamoxifen in patients with idiopathic retroperitoneal fibrosis: an open-label randomised controlled trial., Vaglio A,Palmisano A,Alberici F,Maggiore U,Ferretti S,Cobelli R,Ferrozzi F,Corradi D,Salvarani C,Buzio C,, Lancet (London, England), 2011 Jul 23     [PubMed]
Retroperitoneal fibrosis., Vaglio A,Salvarani C,Buzio C,, Lancet (London, England), 2006 Jan 21     [PubMed]
Retroperitoneal fibrosis: new insights into clinical presentation and diagnosis., Vaglio A,, Medicine, 2009 Jul     [PubMed]
Retroperitoneal fibrosis., Day K,Nikolaidis P,Casalino DD,, The Journal of urology, 2012 Apr     [PubMed]
Computed tomography in the diagnosis of retroperitoneal fibrosis., Dalla-Palma L,Rocca-Rossetti S,Pozzi-Mucelli RS,Rizzatto G,, Urologic radiology, 1981     [PubMed]
Idiopathic retroperitoneal fibrosis and its overlap with IgG4-related disease., Rossi GM,Rocco R,Accorsi Buttini E,Marvisi C,Vaglio A,, Internal and emergency medicine, 2017 Apr     [PubMed]
Retroperitoneal fibrosis treated with methylprednisolon pulse and disease-modifying antirheumatic drugs., Harreby M,Bilde T,Helin P,Meyhoff HH,Vinterberg H,Nielsen VA,, Scandinavian journal of urology and nephrology, 1994 Sep     [PubMed]
Immunosuppressive therapy for idiopathic retroperitoneal fibrosis: a retrospective analysis of 26 cases., Marcolongo R,Tavolini IM,Laveder F,Busa M,Noventa F,Bassi P,Semenzato G,, The American journal of medicine, 2004 Feb 1     [PubMed]
Combined prednisone and mycophenolate mofetil treatment for retroperitoneal fibrosis., Scheel PJ Jr,Piccini J,Rahman MH,Lawler L,Jarrett T,, The Journal of urology, 2007 Jul     [PubMed]
Retroperitoneal fibrosis: the clinical, laboratory, and radiographic presentation., Scheel PJ Jr,Feeley N,, Medicine, 2009 Jul     [PubMed]

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