Retroperitoneal fibrosis associated with immunoglobulin G4-related disease

IgG4-related kidney disease: Clinicopathologic features, differential diagnosis, and mimics

IgG4-related kidney disease (IgG4-RKD) encompasses all forms of kidney disease that are part of IgG4-related disease (IgG4-RD). First recognized as IgG4-related tubulointerstitial nephritis (IgG4-TIN), and then IgG4-related membranous glomerulonephritis (IgG4-MGN), we now recognize additional patterns of interstitial nephritis, glomerular disease, and vascular disease that can be seen as part of IgG4-RKD. The clinical presentation is variable and can include acute or chronic kidney injury, proteinuria or nephrotic syndrome, mass lesion(s), and obstruction. While usually associated with other organ involvement by IgG4-RD, kidney-alone involvement is present in approximately 20 % of IgG4-RKD. Compared to IgG4-RD overall, patients with IgG4-RKD are more likely to show increased serum IgG4 or IgG, and more likely to have hypocomplementemia. In this review, we extensively cover other types of autoimmune and plasma cell-rich interstitial nephritis, mass forming inflammatory diseases of the kidney, and other mimics of IgG4-TIN, in particular ANCA-associated disease.

Systemic Involvement in Immunoglobulin G4-Related Ophthalmic Disease

BACKGROUND

Immunoglobulin G4-related ophthalmic disease (IgG4-ROD) poses clinical challenges due to its heterogeneous ocular and systemic manifestations. We aim to report the systemic involvement and the clinical, serological and radiological associations of a cohort of Chinese patients.

METHODS

A territory-wide, biopsy-proven, Chinese cohort. A retrospective, masked chart review of medical records, orbital images, and histopathology reports.

RESULTS

A total of 122 (65 male) patients with a follow-up of 81 ± 49 (24 to 84) months were reviewed. Ninety (74%) patients presented bilaterally. Subacute upper eyelid swelling was the commonest presentation (82/122, 67%). During follow-up, 91/122 patients (75%) underwent extra-orbital imaging including computer tomography (692 films), ultrasonography (182 films), magnetic resonance imaging (76 films) and whole body FDG-PET scan (33 films). Eighty-six (95%) of these 91 patients had extra-orbital involvement radiologically (2.7 ± 1.6 regions, range: 0 to 9). Lymph node was the most prevalent (N = 60,66%), followed by salivary gland (N = 51,56%), lung (N = 49,54%), kidney (N = 22, 24%), hepatobiliary tree (N = 18, 20%) and pancreas (N = 17, 19%). Other organs include thyroid, aorta, meninges/brain and skin. Twenty-eight (23%) patients had allergic diseases (19 asthma, 16 allergic rhinitis, and 6 eczemas). Fifty-seven (48%) patients had paranasal sinusitis. Serum eosinophilia was associated with a higher number (3.24 versus 2.52, P = 0.0304) of organ involvement. Patients with deep organ involvement was associated with a higher age of IgG4-ROD onset (70 ± 12 versus 56 ± 13, P < 0.0001).

CONCLUSIONS

95% of the patients who underwent systemic imaging in our cohort had systemic organ involvement. An early physicians' assessment and radiological imaging are recommended after the diagnosis of IgG4-ROD.

[The clinical case of IgG4-related thyroid disease in a 6-year-old child]

IgG4-related disease is a rare chronic pathology manifested by lymphoplasmacytic infiltration of one or more organs, the formation of storiform fibrosis, tissue edema, and an increase of IgG4 in the blood. This disease was singled out as an independent nosological unit only in 2001. The incidence is less than 1 in 100,000 people per year. Almost any organ can be affected in IgG4-related disease. The association of Riedel's thyroiditis with IgG4 was established in 2010. Riedel's thyroiditis is an extremely rare inflammatory disease of the thyroid gland, which diagnosis is complicated by an atypical course and the absence of characteristic symptoms. Less than 300 clinical cases of the disease have been described in the world, only two from them were in children. This article presents a clinical case of a 6-year-old boy with Riedel's thyroiditis.

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.

Anatomic and Functional Imaging of Immunoglobulin G4-related Disease and Its Mimics

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is an immune-mediated fibrosclerosing disease with tumefactive lesions infiltrated by IgG4-positive plasma cells. Initially described as autoimmune pancreatitis, IgG4-RD is now recognized as a discrete entity and is found to affect virtually any organ in the body. Common extrapancreatic sites include the biliary tree, salivary glands, periorbital tissue, lungs, kidneys, lymph nodes, aorta, retroperitoneum, and thyroid gland. Diagnosis-which relies on histopathologic, serologic, and radiologic features-can be challenging with the disease underdiagnosed, as IgG4-RD often mimics malignancy, infectious processes, or other immune-mediated conditions. Patients may present with signs of compression of nearby structures due to mass effect or with organ failure when the disease is left untreated. The clinical course is complex, with single- or multiorgan involvement and metachronous or synchronous occurrence of lesions. IgG4-RD responds well to glucocorticoid therapy, disease-modifying antirheumatic drugs, and B-cell-depleting biologic agents; prompt diagnosis is important to avoid delay in treatment and unnecessary pharmacologic or surgical intervention. While imaging features may not be specific for IgG4-RD, functional whole-body imaging with fluorine 18-fluorodeoxyglucose PET/CT is a useful adjunct for localizing extrapancreatic sites for biopsy, monitoring therapeutic response, and demonstrating disease relapse. The authors describe the pancreatic and extrapancreatic sites of involvement in IgG4-RD, with imaging features and patterns to aid in distinguishing IgG4-RD from its mimics through a multimodality approach with emphasis on functional imaging evaluation. ^©RSNA, 2023 Quiz questions in the supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Eosinophilic pancreatitis with serum IgG4-positivity, potentially associated with autoimmune pancreatitis

A 70-year-old man presented with unprovoked weight loss and intermittent left upper quadrant tenderness for one-and-a-half month. Computed tomography revealed irregular cystic lesions in the pancreatic tail. Endoscopic ultrasonography (EUS) revealed pancreatic tail enlargement and giant, thick-walled cysts surrounding the pancreatic tail with no connection with the pancreatic duct. Endoscopic ultrasonography-guided fine-needle aspiration was performed on the enlarged pancreatic parenchyma and thickened cyst wall. Both biopsies showed hyper eosinophilia and few plasma cells. Endoscopic retrograde pancreatography revealed an irregular narrowing of the main pancreatic duct. Pancreatic juice cytology revealed substantial eosinophilia. Blood sampling showed an elevated eosinophil count and immunoglobulin G4 (IgG4) and immunoglobulin E (IgE) levels at the initial examination. We considered the patient to have eosinophilic pancreatitis (EP) with autoimmune pancreatitis, or alternately, EP with IgG4-related retroperitoneal fibrosis (RPF). Upon prednisolone administration, the abdominal pain improved, the peripheral blood eosinophil count decreased to zero, IgG4 and IgE levels decreased, pancreatic enlargement improved, and the cystic lesions disappeared. The condition did not recur within the following 3 years. Both EP and EP with IgG4-related RPF are rare etiologies of pancreatitis, and this case is very instructive.

Serum IgG4 Concentration Is a Potential Predictive Biomarker in Glucocorticoid Treatment for Idiopathic Retroperitoneal Fibrosis

Objectives: To evaluate the management and outcome of idiopathic retroperitoneal fibrosis (iRPF) in Japan, and to identify its clinical biomarker. Methods: We retrospectively analyzed 129 patients with iRPF treated between January 2008 and May 2018 at 12 university and related hospitals. Patients treated with glucocorticoid were analyzed to identify a predictive biomarker. These patients were classified into three groups according to overall effectiveness (no change: NC, complete response: CR, and partial response groups: PR), and each parameter was compared statistically. Results: Male–female ratio was 5:1, and median age at diagnosis was 69 (33–86) years. Smoking history was reported in 59.6% of the patients. As treatment, 95 patients received glucocorticoid therapy with an overall response rate of 84%. As a result, serum concentration of IgG4 was significantly decreased in NC group compared with the other two groups (56.6 mg/dL vs. 255 mg/dL, 206 mg/dL, p = 0.0059 and 0.0078). ROC analysis was performed between the nonresponder (NC) and responder groups (CR + PR) to identify the cut-off value of serum IgG4 as a predictive marker. As a result, AUC of 0.793 was confirmed. Conclusions: Pre-treatment serum IgG4 concentration may have potential as a predictive biomarker of steroid treatment.

Non-infectious diseases of the aorta and large arteries

This article describes the various forms of inflammatory lesions of the aorta and large arteries, including chronic periaortitis, as well as the diagnostic methods are considered. Large vessel vasculitis represent the most common entities, however, there is also an association with other rheumatological or inflammatory diseases, drug-induced or paraneoplastic entities. Instrumental imaging modalities play an important role in the diagnosis.

The contribution of the immune system to genitourinary fibrosis

Fibrotic diseases of the genitourinary tract are devastating and incompletely understood pathologies. These diseases include urethral and ureteral strictures, retroperitoneal fibrosis, and Peyronie's disease. They can contribute to obstructive uropathy and sexual dysfunction. Poor understanding of the pathophysiology of these diseases severely limits our ability to prevent and treat them. Genitourinary fibrotic diseases likely represent related pathologies that share common underlying mechanisms involving wound healing in response to injury. These diseases share the common feature of extracellular matrix abnormalities-such as collagen deposition, transforming growth factor-β accumulation, and dysregulation of collagen maturation-leading to abnormal tissue stiffness. Given the association of many of these diseases with autoimmunity, a systemic pro-inflammatory state likely contributes to their associated fibrogenesis. Herein, we explore the immunologic contribution to fibrogenesis in several fibrotic diseases of the genitourinary system. Better understanding how the immune system contributes to fibrosis in these diseases may improve prevention and therapeutic strategies and elucidate the functions of immunologic contributors to fibrosis in general.

Immunoglobulin G4-Related Thyroid Disease: A Single-Center Experience and Literature Review

BACKGROUND

Immunoglobulin G4 (IgG4)-related disease is an entity that can involve the thyroid gland. The spectrum of IgG4-related thyroid disease (IgG4-RTD) includes Hashimoto thyroiditis (HT) and its fibrotic variant, Riedel thyroiditis, as well as Graves' disease. The early diagnosis of IgG4-RTD is important because it is a medically treatable disease, and a delay in the diagnosis might result in unnecessary surgery. We present a case series of IgG4-RTD with a review of the literature.

METHODS

We retrospectively reviewed the clinical presentation and the radiological and pathological findings of patients diagnosed with IgG4-RTD between 2017 and 2021 at a tertiary medical center in Korea. We also conducted a literature review of IgG4-RTD.

RESULTS

Five patients were diagnosed with IgG4-RTD during the study period. The patients' age ranged from 31 to 76 years, and three patients were men. Most patients visited the clinic for a neck mass, and hypoechogenic nodular lesions were observed on neck ultrasonography. Three patients had IgG4 HT, and two patients had IgG4 Riedel thyroiditis. All patients developed hypothyroidism that necessitated L-thyroxine replacement. The diagnosis of IgG4-RTD was confirmed after a pathological examination of the surgical specimen in the first two cases. However, the early diagnosis was possible after a core needle biopsy in three clinically suspected patients.

CONCLUSION

The diagnosis of IgG4-RTD requires clinical suspicion combined with serology and histological analyses using IgG4 immunostaining. The early diagnosis of IgG4-RTD is difficult; thus, biopsy with IgG4 immunostaining and serum IgG4 measurements will help diagnose patients suspected of having IgG4-RTD.

The Role of IgG4 in Autoimmunity and Rheumatic Diseases

The distinguishing of the IgG4-related disease (IgG4-RD) from among other rheumatic diseases has brought attention to the IgG4 subclass of immunoglobulins. It is the least numerous subclass among immunoglobulins G. In general, IgG4 is considered to be non-inflammatory and tolerance inducing, due to its unique structure. However, in IgG4-RD this antibody plays a pathogenic role in activation of the fibrinogenesis and of the inflammatory process; there are also suggestions that it may be a marker of an abnormal inflammatory response. The importance of IgG4 for the pathogenesis of allergic diseases, with a vital role of its ratio to immunoglobulin E (IgE/IgG4 ratio), has been known for years. The role of IgG4 in the course and pathogenesis of rheumatic diseases is still being researched and is not yet fully understood. Increased IgG4 levels have been revealed in rheumatoid arthritis, although no clear link between this phenomenon and disease activity has been demonstrated. There are articles on the potential importance of IgG4 concentration (of both elevated and decreased serum levels) in Sjogren’s syndrome. Additionally, anti-nuclear IgG4 antibody significant titers have been detected in SLE patients, and it has been suggested that the effect of these antibodies on complement consumption and the production of proinflammatory cytokines may play a role in inhibiting the progression of SLE. IgG4 plays a role in autoimmune diseases other than rheumatic diseases, such as pemphigus, bullous pemphigoid, idiopathic membranous glomerulonephritis, or myasthenia gravis, but also in helmints infections. Research shows the importance of IgG4 in malignancy of neoplasms. Melanoma cells are known to stimulate IgG4 production through a modified Th2-based inflammatory response. The role of this immunoglobulin in cholangiocarcinoma is also considered as possible. The aim of this review article is to discuss the current knowledge of IgG4 not only from the perspective of the IgG4-RD but also from a point of view of other autoimmune diseases with particular emphasis on rheumatic diseases.

Anti-Neuronal IgG4 Autoimmune Diseases and IgG4-Related Diseases May Not Be Part of the Same Spectrum: A Comparative Study

Background

IgG4 is associated with two emerging groups of rare diseases: 1) IgG4 autoimmune diseases (IgG4-AID) and 2) IgG4-related diseases (IgG4-RLD). Anti-neuronal IgG4-AID include MuSK myasthenia gravis, LGI1- and Caspr2-encephalitis and autoimmune nodo-/paranodopathies (CNTN1/Caspr1 or NF155 antibodies). IgG4-RLD is a multiorgan disease hallmarked by tissue-destructive fibrotic lesions with lymphocyte and IgG4 plasma cell infiltrates and increased serum IgG4 concentrations. It is unclear whether IgG4-AID and IgG4-RLD share relevant clinical and immunopathological features.

Methods

We collected and analyzed clinical, serological, and histopathological data in 50 patients with anti-neuronal IgG4-AID and 19 patients with IgG4-RLD.

Results

A significantly higher proportion of IgG4-RLD patients had serum IgG4 elevation when compared to IgG4-AID patients (52.63% vs. 16%, p = .004). Moreover, those IgG4-AID patients with elevated IgG4 did not meet the diagnostic criteria of IgG4-RLD, and their autoantibody titers did not correlate with their serum IgG4 concentrations. In addition, patients with IgG4-RLD were negative for anti-neuronal/neuromuscular autoantibodies and among these patients, men showed a significantly higher propensity for IgG4 elevation, when compared to women (p = .005). Last, a kidney biopsy from a patient with autoimmune paranodopathy due to CNTN1/Caspr1-complex IgG4 autoantibodies and concomitant nephrotic syndrome did not show fibrosis or IgG4+ plasma cells, which are diagnostic hallmarks of IgG4-RLD.

Conclusion

Our observations suggest that anti-neuronal IgG4-AID and IgG4-RLD are most likely distinct disease entities.

Retroperitoneal fibrosis masquerading as pelvi-ureteric junction obstruction - Laparoscopic management

Introduction

Retroperitoneal fibrosis (RPF) is a rare fibro-inflammatory condition which is characterized by development of extensive fibrosis throughout the retroperitoneum. It is classically centred over the anterior surface of the fourth and fifth lumbar vertebrae. It results in entrapment and extrinsic compression of retroperitoneal structures.

Presentation of the case

We present the case of a 69 years old man who was reported to have right pelvi - ureteric junction obstruction on computed tomography, but turned out to have RPF.

Discussion

Retroperitoneal fibrosis commonly causes obstructive uropathy (either unilateral, bilateral or progressing from unilateral to bilateral) and if untreated, renal failure. It has high response/remission rates to glucocorticoid therapy. However, relapse rates are also high. Hence, close surveillance with serial laboratory and imaging investigations, after achieving remission, is key to long term disease control.

Conclusion

Although classical imaging findings, supportive laboratory markers and suggestive/diagnostic histopathology appearances for RPF are well documented, its accurate preoperative diagnosis is not always an assured certainty.

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This case is unique in that the original plan to perform a laparoscopic pyeloplasty, purportedly for right pelvi-ureteric junction obstruction; was aborted ‘on table’ and a laparoscopic ureterolysis performed, instead.

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Though ureteral involvement is bilateral in most cases of retroperitoneal fibrosis, this case is rare and unique in that the patient had unilateral involvement of his ureter (right sided).

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Periaortic fibro-inflammatory mass at the level of the lumbar vertebrae is the hallmark of primary / idiopathic retroperitoneal fibrosis. However in this case, no such imaging finding was noted. Instead, the patient had just obvious unilateral (ride sided) disease on pre-operative imaging.

Retroperitoneal Fibrosis as a presentation with masked multiorgan involvement of IgG4-related disease-demystifying the diagnosis: A case report from Nepal

The timely diagnosis of the disease helps in preventing the progression of RF and unnecessary interventions that may mislead the diagnosis. Biopsy and serum IgG4 both can be non-specific.

[SIGNIFICANCE OF IgG4 IN IDIOPATHIC RETROPERITONEAL FIBROSIS]

(Objective)Retroperitoneal fibrosis is largely divided into the idiopathic and secondary types. Some idiopathic cases include IgG4-related diseases, which are often similar to malignant diseases, such as lymphoma and sarcoma. The diagnostic criteria for IgG4-related disease are used and pathologic examination is necessary for a definitive diagnosis of IgG4-related retroperitoneal fibrosis. The first choice of treatment for IgG4-related retroperitoneal fibrosis is steroid administration, but no consensus has been established regarding its dose and tapering schedule. We investigated the significance of IgG4 in diagnosis and treatment of idiopathic retroperitoneal fibrosis. (Patients and methods)We examined 14 cases diagnosed as idiopathic retroperitoneal fibrosis between April 2013 and March 2019. Serum IgG4 was measured at the time of diagnosis in 13 cases, and changes over time in serum IgG4 before and after the induction of steroid therapy were measured in 6 cases. Computed tomography-guided biopsy was performed on 4 cases. (Results)Of all cases, 1 patient was diagnosed as IgG4-related retroperitoneal fibrosis and 5 patients were classified as possible group. Ten patients were administered steroid therapy. Percutaneous nephrostomy tube was placed in 3 patients and was removed in 2 of these patients after steroid therapy. The serum high levels of IgG4 were confirmed in all 4 patients who were classified into the possible group and who were treated with steroids. (Conclusion)Although histologic examination is necessary for the diagnosis of retroperitoneal fibrosis, tissue collection by open or laparoscopic surgery is highly invasive. CT-guided biopsy may be useful in high-risk cases, such as elderly patients on anticoagulation. After excluding other diseases in high-risk cases, response to empiric steroid therapy may be diagnostic. In the possible group, changes in serum IgG4 levels may reflect the disease condition and might be useful in determining the maintenance dose of steroids.

Relapse patterns and predictors of IgG4-related diseases involved with autoimmune pancreatitis: A single-center retrospective study of 115 patients

OBJECTIVE

Autoimmune pancreatitis is an autoimmune disorder accompanied by clinicopathological manifestations that have been established as immunoglobulin (IgG)4-related diseases (IgG4-RD). Other IgG4-RD are often involved with autoimmune pancreatitis. They sometimes relapse despite a favorable response to steroid therapy. This study aimed to clarify the patterns and risk factors for extrapancreatic relapse.

METHODS

We reviewed the data of 115 patients diagnosed with definite autoimmune pancreatitis type 1 and followed up for > 1 year. We analyzed two items: the timing and pattern of extrapancreatic relapse, and risk factors for relapse with three common manifestations: IgG4-related sclerosing cholangitis (SC), IgG4-related dacryoadenitis and sialadenitis (DS), and IgG4-related retroperitoneal fibrosis (RF).

RESULTS

Remission was achieved in all patients, except one. The extrapancreatic relapse rates were 11.0%, 19.7%, and 40% within 3, 5, and 10 years, respectively. Of 26 patients with extrapancreatic relapse, nine (34.6%) relapsed with a new IgG4-RD. Based on multivariate analysis, the interval between symptom onset and steroid initiation, and the presence of RF at onset were significant risk factors for relapse with SC and RF, respectively.

CONCLUSIONS

Our results indicate that they may be various extrapancreatic relapse patterns especially in autoimmune pancreatitis with other organ involvement. Patients with a delayed initiation of steroids or RF at onset should be carefully followed up as high-risk groups for SC and RF relapse.

Gastrointestinal and Extra-Intestinal Manifestations of IgG4-Related Disease

IgG4-related disease (IgG4-RD) is a chronic relapsing multi-organ fibro-inflammatory syndrome of presumed autoimmune etiology. It is characterized by increased serum levels of IgG4 and tissue infiltration by IgG4⁺ cells. Increased titers of autoantibodies against a spectrum of self-antigens and response to steroids have led to its characterization as an autoimmune disease. However, the pathognomonic antigens probably differ among manifestations, and different antigens or autoantibodies produce similar immune reactions in different organs. Little is known about the pathogenic effects, if any, of serum IgG4 or IgG4⁺ plasma cells in tissues. Despite several animal models of the disease, none truly recapitulates human IgG4-RD. Histologic analyses of tissues from patients with IgG4-RD reveal a dense lymphoplasmacytic infiltrate rich in IgG4⁺ plasma cells, storiform fibrosis, and obliterative phlebitis, although these features vary among organs. Typical presentation and imaging findings include mass-forming synchronous or metachronous lesions in almost any organ, but most commonly in the pancreas, bile duct, retroperitoneum, kidneys, lungs, salivary and lacrimal glands, orbit, and lymph nodes. In all organs, inflammation can be reduced by corticosteroids and drugs that deplete B cells, such as rituximab. Patients with IgG4-RD have relapses that respond to primary therapy. Intense fibrosis accompanies the inflammatory response, leading to permanent organ damage and insufficiency. Death from IgG4-RD is rare. IgG4-RD is a multi-organ disease with predominant pancreatico-biliary involvement. Despite its relapsing-remitting course, patients have an excellent prognosis.

Rituximab for retroperitoneal fibrosis due to IgG4-related disease: A case report and literature review

Retroperitoneal fibrosis (RPF) is a progressive fibroinflammatory disease that can be complicated by urinary obstruction. RPF can be the only manifestation of IgG4-related disease (IgG4-RD). Treatment of IgG4-related RPF is challenging and mostly consists of long-term glucocorticoids leading to significant side effects and treatment intolerance. Recent exploration of the role of rituximab as a B-cell depleting therapy in the treatment of IgG4-RD provides therapeutic potential as a well-tolerated alternative to glucocorticoids. We present a case of IgG4-related RPF for which rituximab was instituted as a steroid-sparing treatment strategy. Following 4 doses, kidney function partially recovered, and the disease went into remission. We discuss the potential merit of rituximab for the treatment of patients with IgG4-related RPF.

[Diseases of connective tissue in IgG4-associated autoimmune diseases]

The IgG4-associated diseases of connective tissue are caused by allergen-mediated autoimmune processes. The retroperitoneum, mesentery and mediastinum as well as other less common localizations, such as the neck, orbit and periarticular connective tissue can be affected. Inflammatory fibrosis is initially dominated by a lymphocytic and plasma cell-rich infiltrate and later by cell-poor storiform fibrosis. Stenosis and occlusion of vessels, ureters and intestines can cause severe complications. Computed tomography (CT) and magnetic resonance imaging (MRI) can be implemented in the diagnostic algorithm to narrow the differential diagnosis, delineate the distribution of fibrosis and reveal complications.

Retroperitoneal fibrosis associated with immunoglobulin IgG4-related disease in the differential diagnosis in retroperitoneal tumors. Case report

The patient was a 55-year-old woman with a 4-month history of pain in left flank that irradiated to the lumbar region. Computed tomography revealed a cystic tumor in the retroperitoneal region that compresses the ureter and left renal pelvis in contact with pancreatic body and tail. Surgery was performed and the definitive pathological report diagnosed nodular retroperitoneal fibrosis associated with IgG4; Ki67-positive in germinal centers (5%) and IgG4-positive (40 plasma cells in 3 fields of 40x) by immunohistochemistry. Retroperitoneal fibrosis is a rare disease, that develops gradually and has an excellent response to steroid management. Surgical treatment is reserved for cases that compromise adjacent structures. Thus, identifying it when studying a retroperitoneal tumor leads to better prognosis and survival.

Idiopathic retroperitoneal fibrosis causing unilateral ureteral and sigmoid colon obstruction: A case report

OBJECTIVE

The present report aimed to present a unique case of idiopathic retroperitoneal fibrosis (RPF) presenting features of unilateral ureteral and sigmoid colon obstruction. RPF is a rare disorder with unclear etiology.

CASE REPORT

A 43-year-old female had a 10-day history of lower right abdominal and lumbar pain. Gynecological examination, ultrasound, and computed tomography (CT) were all suggestive of right ovarian tumor. An enhanced CT showed right-sided hydronephrosis. The patient was diagnosed as having ovarian cancer. Ten days after hospitalization, a right intraureteral stent with a double-J catheter was inserted. Upon exploring the abdomen, unyielding RPF was encountered. A partial sigmoidectomy and colostomy were performed. Postoperative pathological results suggested idiopathic RPF. She received steroid treatments.

CONCLUSION

RPF is a rare disease that can be misdiagnosed. Our understanding about its presentation has to be improved and it should be considered as a differential diagnosis for patients presenting with abdominal diseases.

Elevated serum IgG4 levels in diagnosis and treatment response in patients with idiopathic retroperitoneal fibrosis

Idiopathic retroperitoneal fibrosis (iRPF) may be a manifestation of IgG4-related disease. Measuring serum IgG4 (sIgG4) may be of value in monitoring iRPF, but this has scarcely been evaluated. It is unknown if tamoxifen (TMX) affects sIgG4 levels. We performed a prospective inception cohort study of 59 patients with untreated (re)active iRPF stratified by elevated (>1.4 g/L) or normal sIgG4 level. Changes in sIgG4 levels following TMX initiation and, if treatment failed, during subsequent corticosteroid (CS) treatment were analyzed. The median sIgG4 level was 1.1 g/L (interquartile range (IQR) 0.4-2.2); 24 patients (40%) had elevated sIgG4 level. Patients with elevated sIgG4 tended to present with higher ESR (46 vs. 34 mm/h; P = 0.08) and more frequent locoregional lymphadenopathy adjacent to the mass (41.7 vs. 20.0%; P = 0.08). sIgG4 also correlated with ESR (ρ = 0.26; P = 0.05) and serum creatinine (SC) (ρ = 0.26; P = 0.04). Following TMX initiation, sIgG4 level decreased, particularly when achieving treatment success (P < 0.01). Odds ratio for TMX treatment success in patients with elevated sIgG4 level was 0.77 (95% CI 0.53-1.14; P = 0.19). After adjusting for age, sex, and SC, the odds ratio was 0.78 (95% CI 0.51-1.18; P = 0.24). ROC curve analyses of sIgG4 on a continuous scale and treatment success showed an AUC of 0.62. Treatment success and concurrent sIgG4 decrease (P < 0.01) were achieved in 78% of patients who converted to CS therapy. Patients with elevated sIgG4 level may be more inflammatory than patients with normal sIgG4 level, but this needs further study. TMX affects sIgG4 levels, but to a lesser extent than CSs. sIgG4 cannot be used as an outcome prediction tool, irrespective of which cutoff value was chosen.

Overlap of Post-obstructive Diuresis and Unmasked Diabetes Insipidus in a Case of IgG4-related Retroperitoneal Fibrosis and Tuberoinfundibular Hypophysitis: A Case Report and Review of the Literature

The clinical picture of IgG4-related disease (IgG4-RD) is diverse because various organs can be affected. We describe the case of a 56-year-old man with acute renal failure and tuberoinfundibular hypophysitis due to IgG4-RD. Steroid therapy lowered the serum IgG4 level and ameliorated renal dysfunction, bilateral hydronephrosis and retroperitoneal fibrosis. However, polyuria from post-obstructive diuresis and unmasked central diabetes insipidus ensued. The patient's polyuria continued despite the administration of a therapeutic dose of glucocorticoid; the patient's pituitary swelling and anterior pituitary dysfunction were partially ameliorated. The pituitary swelling recurred seven months later. In patients with IgG4-RD, the manifestation of polyuria after steroid therapy should prompt suspicion of post-obstructive diuresis and the unmasking of central diabetes insipidus.

Pathologically Proven Spontaneous Remission of IgG4-related Retroperitoneal Fibrosis

Some forms of idiopathic retroperitoneal fibrosis (RF) have recently been considered to be a part of the spectrum of immunoglobulin G4 (IgG4)-related disease. This case report is the first description of a spontaneous remission in a patient with pathologically proven IgG4-related RF. Although the pathogenesis and long-term disease behavior of IgG4-related RF remains unknown, we believe that an initial assessment consisting of only careful monitoring might be one important strategy, especially in asymptomatic IgG4-related RF patients without nephropathy, while carefully monitoring these patients for the risk of recurrence.

Immunoglobulin G4-Related Thyroid Diseases

Immunoglobulin G4-related disease (IgG4-RD) is a new disease category involving many organ systems, including the endocrine system in general and the thyroid in particular. Since an initial association was made between hypothyroidism and autoimmune (IgG4-related) pancreatitis, more forms of IgG4-related thyroid disease (IgG4-RTD) have been recognized. Four subcategories of IgG4-RTD have so far been identified: Riedel thyroiditis (RT), fibrosing variant of Hashimoto thyroiditis (FVHT), IgG4-related Hashimoto thyroiditis, and Graves disease with elevated IgG4 levels. Although a male predominance is seen for IgG4-RD in general, RT and FVHT have a female preponderance. The pathogenesis of IgG4-RD is not completely understood; however, genetic factors, antigen-antibody reactions, and an allergic phenomenon have been described. Diagnosis of IgG4-RD requires a combination of clinical features, serological evidence, and histological features. Histology is the mainstay of diagnosis, with IgG4 immunostaining. Although serum IgG4 levels are usually elevated in IgG4-RD, raised serum IgG4 is neither necessary nor adequate for diagnosis. Imaging supports the diagnosis and is a useful tool in disease monitoring. Management of IgG4-RTD is both medical and surgical. Steroids are the first-line treatment and may produce a swift response. Tamoxifen and rituximab are second-line agents used in steroid-resistant patients. Surgical debulking is carried out in RT solely as a procedure to relieve obstruction. Other endocrine associations described with IgG4-RD are hypophysitis and Hashimoto encephalopathy. IgG4-RTD is an uncommon disease entity, and prompt diagnosis and treatment can improve outcomes.

Retroperitoneal fibrosis - the state-of-the-art

Retroperitoneal fibrosis (RPF) is a rare disease, hallmarked by inflammation and deposition of fibrous tissue around the abdominal aorta. This process may spread contiguously and involve adjacent structures, leading to many complications, among which the most frequent and most severe is ureteral obstruction. The condition usually has idiopathic origin (idiopathic retroperitoneal fibrosis – IRF), but can also develop secondarily to a number of factors. The etiology of the disease remains unclear. Current research suggests that about half of the cases of IRF may be a symptom of a recently discovered, clinically heterogeneous immunoglobulin G4-related disease (IgG4-RD). Corticosteroids are the first-line treatment for IRF, but effective attempts to use immunosuppressants are also made. This paper presents the current state of knowledge on the etiopathogenesis, clinical presentation, diagnosis and therapeutic possibilities in different forms of RPF. Based on the latest research, an analysis of the relationship between IRF and IgG4-RD was performed.

IgG4-related retroperitoneal fibrosis: a newly characterized disease

Retroperitoneal fibrosis (RPF) is a rare disease characterized by chronic, nonspecific inflammatory and sclerotic or fibrotic tissue in the periaortic or periiliac retroperitoneum that encases adjacent structures. There will be a series of clinical manifestations once the proliferated fibrous tissues encase the abdominal aorta, iliac arteries and urinary duct. RPF is generally divided into two types: idiopathic retroperitoneal fibrosis (IRPF) without identified pathogenesis, making up about two-thirds of cases, and secondary retroperitoneal fibrosis. Recent studies on Immunoglobulin G4-related disease (IgG4-RD) reveal that abundant infiltration of IgG4 positive plasma cells is found in biopsies on the mass of RPF of some IRPF patients, which is identified as one spectrum of IgG4-RD and is named IgG4-related RPF. IgG4-related RPF is often misdiagnosed as retroperitoneal visceral malignancy and is treated with surgery. In addition, because of its good response to glucocorticoid, early detection and treatment is important. We review the definition, epidemiology, clinical features, diagnostic criteria, treatment and prognosis of IgG4-related RPF in this article to raise awareness of this newly characterized disease.

Retroperitoneal fibrosis due to B-cell non-Hodgkin lymphoma: Responding to rituximab!

Retroperitoneal fibrosis is a rare disease manifesting as chronic soft tissue fibrosis in the retroperitoneum, with potential anatomic and/or functional compromise of adjacent organs. It can be primary (idiopathic) or secondary to other conditions such as cancers, autoimmune disorders, or drugs. We report herein a 66-year-old patient with symptomatic retroperitoneal fibrosis leading to bilateral hydronephrosis and renal failure, in whom, after a complex diagnostic work-up and protracted clinical course, a B-cell non-Hodgkin lymphoma in the retroperitoneal space and several vertebral bodies was identified. The patient was treated with radiation therapy and weekly rituximab infusions, with resolution of hydronephrosis and lower back pain. We include a thorough literature review on etiopathogenesis, diagnosis, therapy, and prognosis of retroperitoneal fibrosis. A meticulous search for malignancy is necessary in this rare condition that, if positive, may have significant therapeutic and prognostic implications.

Acute renal vein thrombosis and nephrotic syndrome in the setting of retroperitoneal fibrosis

Idiopathic retroperitoneal fibrosis (RPF) is a rare disease that involves non-specific inflammation and fibrosis surrounding the aorta. As a result, RPF is a challenging diagnosis to make; patients often seek medical attention after complications arise, such as nephrotic syndrome. The patient in our case report initially complained of flank pain. Laboratory evaluation revealed acute renal failure and nephrotic syndrome with substantial proteinuria. Multiple imaging modalities demonstrated a large, ill-defined, infiltrative retroperitoneal soft tissue mass that encased the great vessels. The patient was also noted to have acute left renal vein thrombosis. Although the patient was eventually diagnosed with RPF of unknown etiology, his clinical course is particularly unique given the rarity of the renal vein thrombosis. This case report adds a value to the medical community by helping to elucidate RPF and exposing its potentially life-threatening complications.

Clinicopathologic characteristics of IgG4-related retroperitoneal fibrosis among patients initially diagnosed as having idiopathic retroperitoneal fibrosis

Abstract Objective. The purpose of our study was to determine the number of IgG4-related retroperitoneal fibrosis (RPF) cases that were initially diagnosed as idiopathic RPF and to investigate clinical characteristics of IgG4-related RPF. Methods. We retrospectively reviewed the medical records of 41 RPF patients who were treated at our tertiary care medical center in South Korea between January 2000 and January 2013. We identified cases of 19 patients in which a diagnosis was made based on percutaneous biopsy or surgery and selected these cases for further analysis. Immunostaining for IgG4 and histopathologic examinations were performed for pathology specimens. Results. In the 19 RPF patients, more than 30 IgG4-positive plasma cells per specimen were identified in 9 cases with dense lymphoplasmacytic infiltrates, storiform fibrosis, or obliterative phlebitis (IgG4-related RPF group). The recurrence rate of IgG4-related RPF was significantly higher than that of idiopathic RPF (67% vs. 10%, p = 0.015). Initial and cumulative steroid dosages were not different between the two groups. Conclusions. We found that 47% of the patients initially diagnosed with idiopathic RPF showed IgG4-related RPF evidence according to the pathology and IgG4-related RPF patients showed higher recurrence rate than idiopathic RPF patients. We suggest that maintenance immunosuppressive therapy is required in IgG4-related RPF patients.

Immunoglobulin G4-Related Retroperitoneal Fibrosis Treated with Hochuekkito, a Kampo Medicine, following Steroid Treatment

We report a case of immunoglobulin G4 (IgG4)-related retroperitoneal fibrosis (RF) with complete remission and no relapses after therapy with steroids and Hochuekkito, a Kampo (i.e. traditional Japanese herbal) medicine. A 62-year-old Japanese man was admitted to our hospital for treatment of a retroperitoneal mass detected by computed tomography. The mass had a maximum diameter of 11.0 cm; it involved the left ureter and was associated with left hydronephrosis. After inserting a ureteral stent, we performed a biopsy by laparotomy. Histopathology revealed IgG4-related RF. The lesion disappeared after 7 months of steroid therapy. We subsequently used Hochuekkito as an alternative maintenance treatment because of steroid-related complications. The patient has not relapsed in the 3 years since starting the medication. To the best of our knowledge, this is the first case of IgG4-related RF treated with Hochuekkito as a maintenance treatment.

Clinical features and comprehensive diagnosis of autoimmune pancreatitis in China

AIM

To search for the key factors of autoimmune pancreatitis (AIP) in China and to improve the early identification of AIP in order to avoid misdiagnosing it as pancreatic carcinoma.

METHODS

Clinical, imaging, laboratory, and pathological data about AIP were collected and analyzed from 1996 to 2011 in The Chinese People's Liberation Army General Hospital.

RESULTS

A total of 33 patients (male 29, female 4) aged 35-76 years (52.3 ± 9.3 years) meeting the International Consensus Diagnostic Criteria for type 1 (n = 32) or type 2 (n = 1) AIP were included. With improved understanding of AIP, the misdiagnosis rate and unnecessary laparotomy rate was decreased from 95.7% (22/23) and 91.3% (21/23) before 2006, to 20.0% (2/10) (p = 0.001) and 0.0% (p = 0.001) respectively after 2006. The major symptoms were jaundice in (24/33, 72.7%) and abdominal pain (12/33, 36.4%). Half of the patients had other accompanied autoimmune disorders. Laboratory tests showed an elevated level of serum IgG in 9 out of 11 patients (81.8%) and an increased eosinophil count in 16 out of 33 patients (48.5%). The serum IgG4 levels were twice the upper limit of the normal value. CT scan showed a low-contrast margin characterized by a capsule-like rim in 24 of 32 patients (75.0%). Pathologic examinations showed fibrosis and infiltration of massive lymphocytes and plasma cells in the pancreas. Prednisone was given to the patients and proved to be quite effective for all of them (12/12, 100%).

CONCLUSION

Type 1 AIP shows a sex predilection compared with type 2 AIP in China. In order to diagnose AIP exactly, a comprehensive strategy, especially including imaging and pathological examination, should be used. With growing awareness, fewer AIP patients with this diagnosis would be misdiagnosed and incorrectly treated.

IgG4-related disease

The term "IgG4-related disease" encompasses several disorders described many years ago under various designations depending on the organ or system involved (e.g., Mikulicz syndrome, Riedel's thyroiditis, and retroperitoneal fibrosis). The clinical presentation varies widely, as one or more organs may be affected, usually in the same region of the body and either synchronously or metachronously. The main targets are the pancreas, bile ducts, salivary glands, lachrymal glands, mediastinal lymph nodes, and retroperitoneum. IgG4-related disease is rare, with an estimated incidence of 0.2 to 1/100,000 in Japan and no available incidence data in occidental countries. Men older than 50 years are predominantly affected. Serum IgG4 levels are often greater than 1.35 g/L. Enlargement of the involved organs, which may be pseudotumoral, is due to a combination of infiltration by T cells and IgG4-expressing plasma cells, storiform fibrosis, and obliterative thrombophlebitis. Glucocorticoid therapy is effective but may be followed by relapses requiring the use of immunomodulating agents such as azathioprine, methotrexate and, more recently, rituximab. IgG4-related disease is not an autoimmune condition related to IgG4 autoantibodies, and neither does it involve immune complexes. Specific joint involvement has been reported in a very small number of patients.