IgG4-related disease (IgG4-RD) is a multi-organ inflammatory immune-mediated illness caused by IgG4-secreting plasma cells infiltrating the tissue. This condition usually affects elderly men. A 90-year-old Chinese male was diagnosed with IgG4-RD based on the new 2019 ACR/EULAR classification criteria, as he had multiple organ involvement. After receiving treatment with glucocorticoids, leflunomide, and gamma-globulin, the patient\'s clinical symptoms significantly improved, confirming the accuracy of the diagnosis. The patient had an 18-year medical history during which the disease progressively worsened due to delayed diagnosis and treatment. Although the relevant symptoms were alleviated with appropriate medication, the overall treatment process encountered challenges. Due to the patient\'s relative lack of adrenocortical function, he experienced symptoms such as nausea, exhaustion, and loss of appetite during the hormone reduction process. Therefore, timely intervention is especially crucial to address the side effects of hormone therapy.

OBJECTIVE: Retroperitoneal fibrosis is a rare disease characterized by chronic inflammation and fibrosis in the retroperitoneal space that may wrap around the ureter and cause an obstruction. Here we present the cases of three patients diagnosed and treated between April and August 2022.
METHODS: Here we present three cases of retroperitoneal fibrosis. Imaging revealed hydronephrosis and/or ureteral dilation, whereas laboratory findings such as erythrocyte sedimentation rate, C-reactive protein, and immunoglobulin G4 were abnormal. Serum creatinine and blood urea nitrogen levels suggested renal injury. Additionally, two patients had unclear diagnoses from other hospitals. Later, all patients underwent ureteral stenting and laparoscopic ureterolysis at our hospital and simultaneous diagnosis by biopsy. The two patients with high immunoglobulin G4 levels exhibited extremely severe fibrosis. After discharge, each received maintenance prednisone to prevent recurrence as well as methotrexate, followed by follow-up every 3 months. Fortunately, serum creatinine, blood urea nitrogen, and intravenous urography findings remained normal with an average follow-up of 8.5 months.
CONCLUSIONS: Here we discovered interesting findings in the diagnosis and treatment of retroperitoneal fibrosis, including the stable effect of medical plus surgical treatment, an unclear ureteral obstruction etiology, and the relationship between immunoglobulin G4 level and fibrosis hardness. However, the mechanisms behind these new findings require further study.

UNASSIGNED: A 5.5-year-old male neutered domestic shorthair cat was presented with a 2-year history of progressive chronic kidney disease. Abdominal ultrasonography revealed bilateral chronic renal degeneration, nephrolithiasis, cortical hyperechogenicity and infarction. Left orthotopic renal transplantation was performed using the Synovis vascular coupling system for end-to-end anastomosis of the renal arteries and veins. Two months after transplantation, renal values were elevated, and abdominal ultrasonography revealed hydronephrosis and hydroureter of the transplanted kidney. Fluoroscopic antegrade pyelography identified a proximal ureteral stricture. Proximal neoureterocystostomy was performed and renal values normalized postoperatively. The cat was re-evaluated for acute stranguria and severe azotemia 12 months later. Contrast-enhanced CT revealed severe hydronephrosis of the transplanted kidney, obstruction of the proximal ureter and adhesions to the urinary bladder. Upon exploration, retroperitoneal fibrosis was found covering the transplanted kidney. Given the clinical situation, a subcutaneous ureteral bypass device (SUB) was placed. Clinicopathologic analyses, trough cyclosporine levels, aerobic urine cultures and ultrasonographic evaluations of the transplanted kidney were monitored every 1-3 months. Patency of the SUB was reassessed every 3-6 months. At 15 months after placement, the SUB occluded due to kinking of the cystostomy catheter and was replaced. At 28 months after SUB placement, renal function and clinical status deteriorated, and the cat was euthanized.
UNASSIGNED: To the authors\' knowledge, this is the first report of a SUB device being used for management of ureteral obstruction in a transplanted kidney in a cat.

We report an interesting case of a 25-year-old male patient who presented with a complaint of pain in the abdomen for six months, which was not associated with any other symptom, the patient was diagnosed with IgG4-related retroperitoneal fibrosis (RF) via endoscopic ultrasound (EUS)-guided biopsy. He was prescribed steroids and proton pump inhibitors. Due to the limited presentation and rarity of RF, diagnosis of this disease requires extensive diligence and care. In this case report, we underscore the importance of considering the differential diagnosis of RF or Ormond\'s disease when a patient presents with vague symptoms of pain in the abdomen. According to our knowledge, this is the first case of IgG4-related RF in a patient with B-cell lymphoproliferative disorder reported from Pakistan.

UNASSIGNED: Retroperitoneal fibrosis (RPF) is a fibroinflammatory disease in which patients may suffer obstructive uropathy (OU). The optimum treatment strategy for RPF with secondary OU is currently unclear, and the aim of this literature review is to assess the methods used to treat this patient cohort.
UNASSIGNED: Medline, Embase, Cinahl, the Cochrane Library and PubMed were systematically searched to find studies assessing treatment outcomes in this patient cohort. After reviewing the studies\' titles, abstracts and full texts, 12 were found that matched our search aims. Data from these publications were analysed and reported.
UNASSIGNED: The demographic and symptomatic features of patients across the 12 studies were representative of the general RPF population. No randomised control trials (RCTs) were found, and just one study formally compared outcomes between patients who underwent different treatment strategies. Many of the studies concluded that using medical and surgical methods in combination led to positive outcomes; whereas, others found positive outcomes following a variety of regimens. Many studies also highlighted, however, that significant minorities required further treatment after initial therapy. Conclusions regarding optimum treatment methods were limited as most publications did not formally compare outcomes following different strategies and had an observational study design.
UNASSIGNED: Although positive outcomes were commonly seen following medical, surgical and a combination of treatments, the literature currently lacks research formally comparing outcomes after assigning specific treatment protocols to groups of RPF patients. More research is therefore required to determine how to best manage RPF leading to secondary OU.

An asymptomatic 75-year-old man who underwent transverse colon cancer surgery two years previously presented with retroperitoneal fibrosis (RPF) around the ventral sacral and right external iliac artery and vein on abdominal computed tomography (CT) during a routine surveillance visit. We assumed cancer recurrence or immunoglobulin G4 (IgG4)-related disease (RD), but although generic tumor markers and IgG4 levels were normal, soluble interleukin 2 receptor (sIL-2R) was elevated at 569 U/mL (reference: 122-496 U/mL). No diagnosis was made at this time, and the patient was followed up. He subsequently developed edema of both lower extremities. Abdominal enhanced CT showed an enlarged RPF without invasion of surrounding organs and with a delayed contrast effect, and positron emission tomography-CT showed fluorodeoxyglucose accumulation in the same area but a lower standardized uptake value (SUV) than at the time of transverse colon cancer diagnosis. Although generic tumor markers and IgG4 levels remained within the reference range, sIL-2R was further elevated to 1100 U/mL. An open biopsy and histopathology showed a high IgG4/IgG-positive cell ratio and infiltration of IgG4-positive plasma cells. The patient was finally diagnosed with IgG4-RD RPF. In cases of RPF after colorectal cancer surgery, the combined findings of elevated sIL-2R, lack of infiltration into surrounding organs, and lower SUV values ​​than at the cancer site could provide useful information to aid the diagnosis of IgG4-RD RPF.

IgG4-related disease (IgG4-RD) is a rare, systemic immune-mediated fibro-inflammatory condition with an unclear etiology and pathophysiology, potentially affecting multiple organs. It presents with common clinical, radiological, and serological characteristics. This study aims to compare the latest two IgG4-RD classification and diagnostic criteria: Umehara-Okazaki 2011 and ACR/EULAR 2019.
In a retrospective cross-sectional study conducted across two centers from January 2010 to July 2023, we included patients suspected of having IgG4-RD from various hospital departments. Patients finally diagnosed with other pathologies were excluded. The remaining suspected IgG4-RD cases were evaluated using both Umehara-Okazaki 2011 and ACR/EULAR 2019 criteria.
Out of 34 patients with a clinical diagnosis of IgG4-RD, the Umehara-Okazaki 2011 classified 20 patients: 5 as definitive, 7 as probable, and 8 as possible cases. Applying the ACR/EULAR 2019 criteria to the same cohort resulted in the diagnosis of 9 patients. Notably, retroperitoneal fibrosis and aortitis were the most prevalent form of presentation, accounting for 25% and 22.2% of cases classified under the 2011 and 2019 criteria, respectively.
The more recent and stringent ACR/EULAR 2019 criteria focus on histopathology, various forms of presentation, and analytical data, allow for a more accurate classification of patients.

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.
UNASSIGNED: This case series provides insight into the various imaging appearances of IgG4-related retroperitoneal organ involvement and helps differentiate it radiologically from 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 (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.