Immunoglobulin G4 disease-related retroperitoneal fibrosis: A series of five cases.

Immunoglobulin G4 (IgG4)-related disease has the potential to impact any part of the body, including the walls of large- and medium-sized blood vessels and the ureters. While histopathologic examination is currently the standard method for identifying organ involvement and diagnosing IgG4-related disease (IgG4-RD), obtaining biopsy or surgical samples from vessel or ureteral walls is challenging. Given that patients may display only mild symptoms, non-invasive imaging plays a vital role in both diagnosing and managing IgG4-related diseases. Multidetector CT scans are valuable in establishing the primary diagnosis, identifying anatomical landmarks and assessing their relationships. Involvement of the genitourinary organs, such as the ureter, bladder, urethra, and male and female reproductive organs in IgG4-RD, is infrequent when compared to kidney involvement. The imaging findings may include the presence of a localised mass within or surrounding the affected organ or a generalised enlargement of the organ. This report includes cross-sectional images of five cases of IgG4-RD involving large- and medium-sized blood vessels (the aorta and superior mesenteric artery) and the ureters. Contribution: This case series provides insight into the various imaging appearances of IgG4-related retroperitoneal organ involvement and helps differentiate it radiologically from retroperitoneal fibrosis.

Combined paraganglioma and IgG4-related retroperitoneal fibrosis.

A paraganglioma is a neuroendocrine tumor that may secrete catecholamines and present with symptoms of sympathetic overload such as hypertension and diaphoresis. It is important that paragangliomas are identified, as they must often be treated by surgical excision. IgG4-related retroperitoneal fibrosis (IgG4-RPF) is a systemic inflammatory disease that results in the infiltration of IgG4-positive plasma cells in the retroperitoneum. Such fibrosis may adversely affect nearby organs and tissues. Here, we describe a case of combined paraganglioma and IgG4-RPF in a 47-year-old female patient. This case demonstrates the deleterious effect of these two conditions when they occur simultaneously.

Retroperitoneal Fibrosis: A Puzzle of Elusive Causal Link.

Retroperitoneal fibrosis (RPF) is a rare condition characterized by the presence of fibro-inflammatory tissue surrounding the abdominal aorta and iliac arteries, often leading to the involvement of adjacent organs such as the ureters and inferior vena cava. We present a case report of a 56-year-old Caucasian woman with a complex medical history, including Hodgkin's lymphoma treated with chemotherapy and radiotherapy (31 years before), a significant smoking history, and a current presentation of acute kidney injury with oliguria, edema, and hypertension. Initial diagnostic considerations included rapidly progressive glomerulonephritis, supported by clinical and imaging findings. However, the absence of specific autoantibodies and the presence of bilateral calyx-pelvic dilation raised questions regarding alternative diagnoses. Imaging studies, including CT, contrast-enhanced CT, and subsequent MRI, revealed periaortic and paracaval adipose tissue thickening suggestive of periaortitis, leading to a diagnosis of retroperitoneal fibrosis. The multifactorial etiology, including previous radiation therapy, lymphoma history, and significant smoking, posed challenges in establishing a definitive causal link. Despite extensive investigations, including laboratory tests and imaging modalities, no single etiological factor could be conclusively identified. This case underscores the diagnostic complexity of RPF, especially in the presence of multiple potential risk factors, and highlights the importance of considering this condition in the differential diagnosis of patients presenting with renal dysfunction and obstructive uropathy.

Atypical Presentation of Retroperitoneal Fibrosis Causing Colonic Obstruction: A Case Report.

Retroperitoneal fibrosis (RPF), also referred to as Ormond's disease, is a rare fibroinflammatory condition characterized by abnormal fibrous tissue deposition in the retroperitoneal space, which traditionally presents with ureteral obstruction. Nonetheless, our case report showcases an exceptional instance involving a 70-year-old female patient who presented with symptoms suggestive of colonic obstruction, an unusual presentation that is not commonly associated with RPF. Although RPF has established associations with autoimmune conditions such as immunoglobulin G4-related disease and systemic lupus erythematosus, its connection to colonic obstruction remains undocumented in the medical literature. Our patient is a 70-year-old female who presented with constipation, anemia, and fecal occult blood. Her past medical history included a hysterectomy due to fibroids, right breast lumpectomy, type 2 diabetes mellitus, subclinical hyperthyroidism, hypertension, and obesity. Upon physical examination, the patient's abdomen appeared protuberant but was non-tender to palpation. Bowel sounds were normal, and there was no distension. Notably, there was no tenderness in the right or left costovertebral angles, nor was there any guarding. Workup with colonoscopy could not be completed due to the inability to pass a colonoscope beyond the rectosigmoid junction. Further workup with barium enema confirmed an apple core lesion seen in the rectosigmoid concerning for a neoplastic or inflammatory process. Finally, a computed tomography scan of the abdomen and pelvis showed a 7.1 cm right pelvic mass attached to the bladder and cecum, moderate right hydroureteronephrosis, and a 5.2 cm left adnexal mass with soft tissue changes narrowing the sigmoid colon. The next step was to take the patient for an exploratory laparotomy. During exploratory laparotomy, extensive adhesions and desmoplastic reactions were observed in the pelvic region, involving the sigmoid colon, bladder, cecum, and appendix. Two firm masses were identified in the retroperitoneum, one located in the left lower quadrant (LLQ) adherent to the posterior wall of the sigmoid colon and one in the right lower quadrant (RLQ) adherent to the posterior wall of the cecum. Three specimens were sent to pathology for further examination: a portion of the sigmoid colon, a resection from the RLQ mass, and a resection from the LLQ mass. Pathology reported dense fibrotic masses with abscess-like formation, reactive in nature and of unclear etiology, and negative for malignancy. They were negative for fibromatosis (ß-catenin negative), and IgG4+/IgG+ was approximately 5%. Interestingly, the LLQ mass also contained remnants of the fallopian tube and ovary and benign cystic changes. This case report presents a unique and atypical presentation of RPF, deviating from the conventional presentation of ureteral obstruction. The patient's initial symptoms suggested colonic obstruction, a clinical scenario rarely linked to RPF. This case underscores the significance of considering diverse clinical presentations when diagnosing RPF, thereby expanding our comprehension of the condition's clinical spectrum and ultimately refining patient care and management.

Bessel's disease-the first report of an IgG4-related disorder.

Many aspects of IgG4-related diseases were initially described during the late 19th and early 20th century. A variety of clinical presentations caused by this common pathology have been named after the researchers who first described the disorders, such as Mikulicz, Küttner, Riedel or Ormond. However, the initial description of retroperitoneal fibrosis dates back to even 50 years earlier, when in 1846, the Prussian private practitioner Raphael Jakob Kosch described a hitherto unknown constellation of symptoms and pathological findings in a famous patient. This celebrity was the mathematician and astronomer Friedrich Wilhelm Bessel, a close friend of Alexander von Humboldt and Carl Friedrich Gauss.

A retrospective analysis of perioperative complications of lateral approach lumbar interbody fusion in patients with prior abdominal surgery or a history of colonic inflammatory disease.

BACKGROUND CONTEXT: Lateral approaches for lumbar interbody fusion (LIF) allow for access to the lumbar spine and disk space by passing through a retroperitoneal corridor either pre- or trans-psoas. A contraindication for this approach is the presence of retroperitoneal scarring that may occur from prior surgical intervention in the retroperitoneal space or from inflammatory conditions with fibrotic changes and pose challenges for the mobilization and visualization needed in this approach. However, there is a paucity of evidence on the prevalence of surgical complications following lateral fusion surgery in patients with a history of abdominal surgery. PURPOSE: The primary aim of this study is to describe the association between surgical complications following lateral interbody fusion surgery and prior abdominal surgical. STUDY DESIGN: Retrospective study. PATIENT SAMPLE: Patients over the age of 18 who underwent lateral lumbar interbody fusion at a large, tertiary care center between 2011 and 2019 were included in the study. OUTCOME MEASURES: The primary outcome included medical, surgical, and thigh-related complications either in the intraoperative or 90-day postoperative periods. Additional outcome metrics included readmission rates, length of stay, and operative duration. METHODS: The electronic health records of 250 patients were reviewed for demographic information, surgical data, complications, and readmission following surgery. The association of patient and surgical factors to complication rate was analyzed using multivariable logistic regression. Statistical analysis was performed using R statistical software (R, Vienna, Austria). RESULTS: Of 250 lateral interbody fusion patients, 62.8% had a prior abdominal surgery and 13.8% had a history of colonic disease. The most common perioperative complication was transient thigh or groin pain/sensory changes (n=62, 24.8%). A multivariable logistic regression considering prior abdominal surgery, age, BMI, history of colonic disease, multilevel surgery, and the approach relative to psoas found no significant association between surgical complication rates and colonic disease (OR 0.40, 95% CI 0.02-2.22) or a history of prior abdominal surgeries (OR 0.56, 95% CI 0.20-1.55). Further, the invasiveness of prior abdominal surgeries showed no association with overall spine complication rate, lateral-specific complications, or readmission rates (p>.05). CONCLUSION: Though retroperitoneal scarring is an important consideration for lateral approaches to the lumbar spine, this study found no association between lateral lumbar approach complication rates and prior abdominal surgery. Further study is needed to determine the impact of inflammatory colonic disease on lateral approach spine surgery.

Validation of the Diagnostic Criteria for IgG4-Related Periaortitis/Periarteritis and Retroperitoneal Fibrosis (IgG4PA/RPF) 2018, and Proposal of a Revised 2023 Version for IgG4-Related Cardiovascular/Retroperitoneal Disease.

BACKGROUND: In 2018, diagnostic criteria were introduced for IgG4-related periaortitis/periarteritis and retroperitoneal fibrosis (PA/RPF). This study assessed the existing criteria and formulated an improved version.Methods and Results: Between August 2022 and January 2023, we retrospectively analyzed 110 Japanese patients diagnosed with IgG4-related disease (IgG4-RD) involving cardiovascular and/or retroperitoneal manifestations, along with 73 non-IgG4-RD patients ("mimickers") identified by experts. Patients were stratified into derivation (n=88) and validation (n=95) groups. Classification as IgG4-RD or non-IgG4-RD was based on the 2018 diagnostic criteria and various revised versions. Sensitivity and specificity were calculated using experts' diagnosis as the gold standard for the diagnosis of true IgG4-RD and mimickers. In the derivation group, the 2018 criteria showed 58.5% sensitivity and 100% specificity. The revised version, incorporating "radiologic findings of pericarditis", "eosinophilic infiltration or lymphoid follicles", and "probable diagnosis of extra-PA/-RPF lesions", improved sensitivity to 69.8% while maintaining 100% specificity. In the validation group, the original and revised criteria had sensitivities of 68.4% and 77.2%, respectively, and specificities of 97.4% and 94.7%, respectively. CONCLUSIONS: Proposed 2023 revised IgG4-related cardiovascular/retroperitoneal disease criteria show significantly enhanced sensitivity while preserving high specificity, achieved through the inclusion of new items in radiologic, pathological, and extra-cardiovascular/retroperitoneal organ categories.

Urothelial carcinoma masquerading as retroperitoneal fibrosis: A case report.

Retroperitoneal fibrosis, a rare and often idiopathic condition, poses significant diagnostic challenges. While most cases are considered idiopathic or immune-mediated, a small but important proportion are associated with malignant neoplasms, with implications for prognosis and management. The present study describes the case of a 69-year-old man who presented to the emergency department of the Virgen de las Nieves University Hospital (Granada, Spain), with a 2-week history of epigastric pain, vomiting and altered bowel habits. Laboratory investigations revealed previously undiagnosed renal insufficiency. An abdominal computed tomography (CT) scan showed extensive diffuse retroperitoneal infiltration extending from the periduodenal region to the pubic bone, resulting in gastric dilatation and hydronephrosis. A CT-guided retroperitoneal biopsy was performed and pathology confirmed the presence of urothelial carcinoma. This diagnosis led to the initiation of a chemotherapy regimen consisting of carboplatin and gemcitabine specifically designed for urothelial carcinoma. A follow-up 18F-FDG PET scan performed 6 months later showed a partial functional response. This case illustrates a rare presentation of urothelial carcinoma masked by extensive retroperitoneal fibrosis, and highlights the importance of accurate diagnosis in reducing tumor burden and improving the clinical status of patients.

Diagnostic value of contrast-enhanced ultrasound in the activity of idiopathic retroperitoneal fibrosis: a retrospective study.

OBJECTIVES: To explore the diagnostic value of contrast-enhanced ultrasound (CEUS) in the disease activity of idiopathic retroperitoneal fibrosis (IRPF). METHODS: This retrospective study included 148 CEUS examinations from 63 patients with IRPF treated in our hospital from April 2016 to September 2021. They were divided into two groups: IRPF active group (69 examinations) and inactive group (79 examinations). Uni- and multivariable analyses were used to identify independent risk factors for IRPF activity. Receiver operating characteristic (ROC) curves were drawn to establish different diagnostic models to evaluate the diagnostic value of IRPF activity. The z test was used to compare the differences of the area under the curves (AUCs). The value of CEUS in evaluating the variation of disease activity over time was also investigated between repeat patient studies. RESULTS: Univariate and multivariate logistic regression analyses revealed the thickness [odds ratio (OR) = 14.125, 95% confidence interval (CI) = 3.017-66.123] was the most significant independent risk factor for IRPF activity (P < 0.01). The best diagnostic model was model 3, which was established by CEUS score combined with thickness. The AUC was 0.944 (95%CI = 0.912-0.977), and the sensitivity and specificity were 89.86% and 86.08%, respectively. The diagnostic performance was not significantly improved after combining clinical symptom (back pain) and laboratory indicators [erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)]. Compared with before treatment, the CEUS score and thickness were significantly decreased after treatment (x2 = 14.580, P < 0.001 and z = 4.708, P < 0.001, respectively). CONCLUSION: CEUS has good diagnostic value for IRPF disease activity. Key points • Thickness and contrast-enhanced ultrasound score were significantly higher in the active group than those in inactive group (P < 0.001). • With thickness of 4 mm and contrast-enhanced ultrasound 2 score as optimal cut-off values, the sensitivity and specificity were 89.86%, 81.01% and 52.17%, 100.00%, respectively. • During follow-up, when the disease progressed, the change of CEUS score was earlier than the change of thickness.

IgG4-Related Kidney Disease: A Diagnostic Conundrum Successfully Treated With Steroids and Rituximab.

IgG4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory condition that has been recognized as a unified systemic disease that links many individual organ conditions that were previously considered to be unrelated. The pathological hallmark of the disease is an abundant IgG4-positive plasma cell infiltration in the affected tissues and fibrosis. It is a great mimicker of neoplastic, inflammatory, and infectious conditions. We report a 72-year-old man who presented to our hospital with dyspnea and oliguria. Detailed evaluation revealed that he was treated at multiple places for right-sided loin pain over the past 10 months and was found to have right-sided hydronephrosis, renal dysfunction, and multiple enlarged lymph nodes. A search for underlying malignancy previously was unyielding and he had rapid worsening of renal function prior to the current presentation. He was uremic and was initiated on hemodialysis. Kidney biopsy revealed features of IgG4-related tubulointerstitial nephritis. Despite tubular atrophy and interstitial fibrosis involving more than 50% of the sampled cortex, he showed a good response to steroids and rituximab (RTX) and became dialysis-independent. This report underscores the masquerading presentation of IgG4-RD which can hinder timely diagnosis and demonstrates the usefulness of a regimen of steroids and RTX in its treatment.

Zinner's Syndrome and Retroperitoneal Fibrosis: An Unknown Association.

We report the case of a 24-year-old male presenting with obstructive renal failure, characterised by imaging evidence of a cystic lesion contingent upon the seminal vesicle and concurrent renal agenesis. Initial management involved urinary diversion, followed by outpatient monitoring and subsequent recurrence. Subsequent diagnostic assessments led to the identification of Zinner's syndrome, accompanied by retroperitoneal fibrosis. We present the clinical course, diagnostic methodology and the efficacious implementation of medical-surgical therapeutic interventions, yielding favourable outcomes. LEARNING POINTS: The value of the Internal Medicine team in the assessment of low prevalence diseases.The importance of multidisciplinary teams.Integration of the internists in the surgical teams.

IgG4-related retroperitoneal fibrosis induced by nivolumab and ipilimumab in a patient with non-small cell lung cancer: A case report.

IgG4-related diseases are adverse events that occur after receiving treatment with immune checkpoint inhibitors (ICI). This study reports the first case of IgG4-related retroperitoneal fibrosis after the administration of chemotherapy with nivolumab and ipilimumab (NI therapy). An 80-year-old man developed lower abdominal pain eight months after NI therapy was initiated. Although the primary lesion maintained its reduced size on computed tomography, there was an increase in the soft tissue shadows intensity around the abdominal aorta, bladder, and seminal vesicles, suggesting retroperitoneal fibrosis. Blood tests showed elevated IgG4 levels. Computed tomography-guided biopsy of the retroperitoneum showed B cell-dominant lymphocyte infiltration consistent with IgG4-related retroperitoneal fibrosis and characteristic CD8-positive lymphocyte infiltration, suggestive of the involvement of cytotoxic T cells. Based on the clinical, imaging, and pathological findings, the patient was diagnosed with IgG4-related retroperitoneal fibrosis due to ICI. Immunotherapy discontinuation alone did not result in improvement; therefore, steroid therapy was initiated. In clinical practice, IgG4-related retroperitoneal fibrosis can occur as an immune-related adverse event when administering anti-PD-1 and anti-CTLA-4 antibodies for cancer immunotherapy. Early steroid therapy could be effective in controlling this immune-related adverse event.

IgG4-related periaortitis presenting as left flank pain.

We present the case of periaortitis which presented initially with left flank pain. A diagnosis of IgG4-related disease (IgG4-RD) was subsequently made and managed as such. IgG4-RD is rare, can be difficult to diagnose, and requires clinical, serological, radiological and pathological correlation, particularly given that serum IgG4 levels may be normal. Immunosuppression is the mainstay treatment for this chronic condition alongside regular rheumatology input.

Rotura de aorta abdominal en fibrosis retroperitoneal idiopática / Abdominal aortic rupture in idiopathic retroperitoneal fibrosis

Introducción: la fibrosis retroperitoneal (FRP) es una enfermedad poco frecuente que se caracteriza por la formación de tejido inflamatorio y fibroso en el espacio retroperitoneal, alrededor de la aorta abdominal y de las arterias ilÍacas, incluyendo con frecuencia los uréteres. Caso clínico: describimos el caso de un paciente de 90 años con diagnóstico de FRP tratado previamente con metilprednisona que acudió a urgencias por la rotura de un aneurisma inflamatorio de la aorta abdominal. Discusión: en las formas de FRP asociadas con aneurisma aórtico abdominal se recomienda tratamiento quirúrgico o endovascular cuando el diámetro aórtico es superior a 5,5 cm o tiene un crecimiento rápido (> 1 mm al mes), ya que el peligro de ruptura parecería no ser mayor que para los aneurismas ateroscleróticos. Sin embargo, no existen pautas ni algoritmos a seguir en el manejo vascular de pacientes con FRP y una aorta “no aneurismática” ante el fracaso del tratamiento con esteroides. Por otro lado, está descrito el riesgo de remodelación arterial y dilatación aórtica progresiva durante el tratamiento con esteroides. Aunque tales cambios suelen ser subclínicos, se han reportado casos que requirieron tratamiento quirúrgico por ruptura, como en nuestro paciente, en el que la complicación ocurrió a pesar de tener un diámetro aórtico máximo inferior a 4 cm.(AU)

Introduction: retroperitoneal fibrosis (RPF) is a rare disease characterized by the formation of inflammatory and fibrous tissue in the retroperitoneal space, around the abdominal aorta and iliac arteries, often including the ureters. Case report: we present a 90-year-old male patient with RPF treated with meprednisone, who attended to the emergency room due to a ruptured inflammatory abdominal aortic aneurysm.Discussion: in RPFs associated with abdominal aortic aneurism, endovascular or surgical treatment is recommended when the aortic diameter is larger than 5.5 cm or when it is rapidly growing (> 1 mm/month) because the danger of rupture would appear to be the same as atherosclerotic aneurysms. However, there are no guidelines or algorithms to follow the vascular management of patients with PRF and a "non-aneurysmal" aorta in the event of failure steroid treatment. On the other hand, the risk of arterial remodeling and progressive aortic dilatation during steroids treatment has been described. Although the changes are subclinical, there were reported cases in which the patients received surgical treatment due to the rupture, such as in our patient where a complication occurred despite having a maximum aortic diameter of less than 4 cm. Recently, a series of 6 patients with RPF non-aneurysmal abdominal aorta, that had not responded properly to medical treatment, received infrarenal abdominal aorta endovascular exclusion.(AU)

3D Laparoscopic Ureterolysis for Retroperitoneal Fibrosis Secondary to Radical Hysterectomy and Radiation Treatment for Cervical Cancer: Results from the Oncological Institute, Cluj Napoca.

BACKGROUND: Ureterolysis represents the surgical treatment for retroperitoneal fibrosis. The aim of the study was to review the outcomes of patients who had undergone radical hysterectomy and radiotherapy for cervical cancer that later developed retroperitoneal fibrosis, for whom 3D laparoscopic ureterolysis was performed in our department and to review current published studies. METHODS: We present a series of cases consisting of 6 patients with secondary retroperitoneal fibrosis. In all cases, the intervention was performed by the same surgeon from the Oncological Institute "Prof. Dr. Ion Chiricuța" Cluj-Napoca, Romania. We carried out a literature review, searching in the PubMed and MEDLINE studies published between 2000 and 2021 relevant to the matter and a total of 12 papers were selected. We reviewed the functional outcomes of patients that underwent minimally invasive ureterolysis. RESULTS: 3D laparoscopic ureterolysis was performed in 6 patients. Mean operative time was 166 minutes and mean blood loss was 203 mL. No surgery required conversion. Five patients showed good functional results after ureteral stent removal. In one case, the patient developed acute pyelonephritis and the ureteral stents were kept. CONCLUSIONS: Laparoscopic ureterolysis for retroperitoneal fibrosis secondary to operated and radiation-treated cervical cancer represents one of the most complex and challenging surgeries in the urological field. From personal experience we conclude that in oncological centers with vast experience in laparoscopy this minimally invasive approach is feasible and safe. Published data, even though scarce, strengthens our results and the need for this surgery in patients with retroperitoneal fibrosis with urological impact. The laparoscopic approach comes with good functional results and with the advantages of faster post-operative recovery comparing to open surgery and comparable results with the precision and dexterity offered by the robotic approach, but with lower economic burden.

[IgG4-related disease: A proteiform pathology with frequent chest manifestations]. / Maladie associée aux IgG4 : une maladie protéiforme aux manifestations thoraciques fréquentes.

INTRODUCTION: While IgG4-related disease (IgG4-RD) was initially described in the early 2000s, its polymorphic clinical manifestations were previously reported under different names ; they have in common the presence of IgG4+ oligoclonal plasma cells and fibrosis. STATE OF THE ART: Ruling out certain differential diagnoses, the diagnosis of IgG4-RD is based on a bundle of clinical, biological and histological features. Chest involvement is variable and can affect the mediastinum, bronchi, parenchyma, pleura and/or, more rarely, bones and (pericardium, aorta, coronary…) vascular structures. The most frequent radiological manifestations are peribronchovascular thickening, mediastinal lymphadenopathy, and nodular or interstitial patterns. Pleural involvement and posterior mediastinal fibrosis are less frequent, while thoracic paravertebral tissue thickening is highly specific. Systemic corticosteroids are the cornerstone of treatment. In case of relapse or as frontline therapy in case of risk factors for relapse and/or poor tolerance of corticosteroids), a steroid-sparing agent (most often rituximab) is added, and biannual maintenance infusions are associated with a lower risk of relapse. PERSPECTIVES: An international consensus has recently led to the development of classification criteria that should standardize the diagnostic approach and homogenize the enrolment of patients in epidemiological as well as therapeutic studies. Other treatments are also under evaluation, including biologics targeting T2 inflammation, CD-19 (inebilizumab, obexelimab), SLAMF7 (elotuzumab) surface proteins, Bruton's tyrosine kinase, and the JAK/STAT pathway. CONCLUSIONS: Substantial progress has been made over recent years in understanding IgG4-RD pathophysiology, and personalized patient care seems to be an achievable medium-term goal.

Clinical Characteristics of Retroperitoneal Fibrosis Patients at a Tertiary Hospital in Japan.

Retroperitoneal fibrosis (RPF) is a rare cause of hydronephrosis and progressive renal dysfunction with unidentified origin. RPF is categorized into idiopathic RPF with/without immunoglobulin G4 (IgG4)-related disease (IgG4-RD), and secondary RPF. Identifying the underlying cause is challenging and often associated with delayed diagnosis or therapeutic interventions. We investigated RPF's clinical characteristics based on different etiologies and factors that may help distinguish the underlying causes. We analyzed the cases of 49 patients with RPF that was radiographically diagnosed at our institution (2008-2022). The cohort was 77.6% males; 75.5% had idiopathic RPF and 24.5% had secondary RPF. Among the idiopathic patients, 54.1% had IgG4-RD. The patients were likely to have abdominal pain, lower back pain/lumbago, and constitutional symptoms including generalized fatigue and fever. The idiopathic patients were likely to have higher serum IgG4 and IgG levels and lower serum C3 levels compared to secondary RPF. The IgG4-RPF patients were likely to have higher serum IgG4 levels and lower serum C-reactive protein, ferritin, and C3 levels compared to the idiopathic RPF patients without IgG4-RD. These findings might reflect underlying systemic inflammatory responses. Comprehensive laboratory testing, including serum inflammatory markers and immunological panels, is recommended for radiologically diagnosed RPF patients.

IgG4-related retroperitoneal fibrosis: A case report of a challenging disease.

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is a multi-organ immune-mediated fibroinflammatory disorder that may imitate malignancy, infectious or any other inflammatory disorder. IgG4-related retroperitoneal fibrosis (IgG4-RPF) is a rare form of IgG4-RD, diagnosis of which is often relied on radiological technology. Herein, we describe a case of 60 year old male, presenting with low back pain and weight loss for a period of 2 months and 15 days. Imaging studies showed a retroperitoneal tumorous mass along with bilateral hydroureteronephrosis, which was later confirmed to be IgG4-related retroperitoneal fibrosis on the basis of extensive histopathological analysis. Immunosuppressive therapy resulted in a decrease in fibrosis and restoration of renal function.

Investigating the Link Between Low Back Ache, Abdominal Discomfort and Oliguria: A Unique Case of Histopathology-Proven Retroperitoneal Fibrosis.

Retroperitoneal fibrosis (RPF) is a rare condition characterized by systemic inflammation and the proliferation of fibroinflammatory tissues in the retroperitoneum. It may lead to the formation of a retroperitoneal mass and can encase the aorta, its branches and ureters. The pathogenesis of RPF is not fully known. We report a case of a 52-year-old male presented with low back ache, flank pain, swelling of legs, oliguria and features of obstructive uropathy, later diagnosed to be RPF. The mainstay of diagnosis includes blood workup, imaging and biopsy. The first line of treatment is corticosteroids. Surgical intervention is carried out when medical measures have failed or when contraindicated. Early diagnosis and prevention of complications is the key, and a high degree of suspicion is needed.