The clinical course of patients with IgG4-related kidney disease. Kidney Int. 2013;84:826-833. [PMID: 23698232 DOI: 10.1038/ki.2013.191]

Progression to end-stage renal disease due to IgG4-related nephritis: a case report

IgG4-related disease (IgG4-RD) is a rare but increasingly recognised condition that can involve multiple organs, including the kidneys which often presents as tubulointerstitial nephritis. Treatment with glucocorticoids is the first line of therapy, but other options may be needed in refractory cases. This case report explores a 68-year-old female, diagnosed with the patient initially responded to glucocorticoids but had a relapse, leading to progressive renal insufficiency and ultimately death. Our case is a rare case observing the progression to end-stage kidney disease from IgG4-RD, and the first case of which the patient had died in a short period.

Efficacy of Rituximab in Autoimmune-Mediated IgG4 Pancreaticobiliary Disease: A Systematic Review and Meta-Analysis

BACKGROUND AND AIMS

IgG4 pancreaticobilliary disease (IgG4-PBD) typically shows a rapid improvement with glucocorticoid treatment, yet most patients experience a recurrence. Rituximab (RTX) has emerged as a hopeful approach to prevent relapses in IgG4-PBD. Nevertheless, there is a lack of data on the efficacy and safety of RTX in IgG4-PBD. In this study, we aim to perform a systematic review and meta-analysis to study the pooled efficacy of RTX in this patient population.

METHODS

Multiple databases, including MEDLINE, SCOPUS, and Embase, were searched (in March 2024) using specific terms for studies evaluating the efficacy and safety of RTX in IgG4 pancreatic biliary disease. Outcomes of interest were relapse, remission, partial remission rates, and adverse events. Standard meta-analysis methods were used using the random-effects model. I2% heterogeneity was used to assess the heterogeneity.

RESULTS

Twelve studies were included in the study (257 patients). The pooled rate of complete remission was 68% (54% to 80%), I2 =53%, respectively. The pooled relapse rate was 23% (13% to 36%), I2=64%. The pooled rate of total adverse events was 21% (12% to 35%), I2=52%. The pooled partial remission rate is 16% (7% to 32%), I2=25%. The pooled rate of complete and partial remission was 81% (66% to 90%), I2=75%. The pooled infusion reaction and infection were 12% (7% to 18%), I2=0% and 14% (8% to 22%), I2=16%, respectively.

CONCLUSION

RTX therapy appears effective in inducing and maintaining remission of pancreaticobiliary disease with a low rate of side effects. RTX presents as a promising treatment option for patients grappling with recurrent or unresponsive IgG4-related ailments. In addition, RTX emerges as an attractive alternative for individuals intolerant to steroids or experiencing IgG4-related disease relapses. Future studies comparing RTX with other immunomodulators will offer deeper insights into relapse factors and elucidate the appropriateness of utilizing this maintenance treatment following the initial flare.

Clinicopathologic Features of IgG4-Related Kidney Disease

Introduction

IgG4-related disease (IgG4-RD) is a systemic immune-mediated disease that can involve nearly any organ. IgG4-RD can affect the kidney in different disease patterns, collectively referred to as IgG4-related kidney disease (IgG4-RKD).

Methods

We conducted a tissue-based cohort study with clinicopathological correlation in 125 patients with IgG4-RKD.

Results

The mean age at biopsy (n = 120) or nephrectomy (n = 5) was 63 years; 80% were male. One hundred eighteen patients (94%) had IgG4-related tubulointerstitial nephritis (IgG4-TIN); 20 patients (16%) had IgG4-related membranous glomerulonephritis (IgG4-MGN; 13 with concurrent IgG4-TIN). The primary clinical indication for biopsy/nephrectomy was acute or chronic renal failure in 78%, proteinuria in 17%, and mass lesion(s) in 15% (with overlap in primary indication). Fifty-two percent patients (41/79) had abnormal radiographic findings, including masses in 30% (24/79). All patients with IgG4-MGN had proteinuria. Extrarenal involvement by IgG4-RD was present in 79%. Median serum creatinine at presentation was 2.5 mg/dl (range 0.7-12). Serum IgG and/or IgG4 was increased in 91% (53/58); hypocomplementemia was present in 56% (43/77). Light microscopy showed plasma cell-rich interstitial nephritis in all cases of IgG4-TIN. Ninety-two percent of patients showed increased IgG4+ plasma cells. Seven percent showed an acute interstitial nephritis (AIN) pattern, and 5% showed non-necrotizing arteritis. Tubular basement membrane immune deposits were present in 83% of IgG4-TIN. Treatment information was available for 71 patients; 62 were treated with immunosuppression. Of those with elevated creatinine, 72% (41/57) showed a treatment response.

Conclusion

This largest tissue-based series more clearly defines the disease phenotype of IgG4-RKD.

Renal Manifestations of IgG4-Related Disease: A Concise Review

IgG4-related disease (IgG4-RD) is an immune-mediated disorder marked by fibro-inflammatory masses that can infiltrate multiple organ systems. Due to its relatively recent discovery and limited understanding of its pathophysiology, IgG4-related disease may be difficult to recognize and is consequently potentially underdiagnosed. Renal involvement is becoming regarded as one of the key features of this disease. To date, the most well-recognized renal complication of IgG4-related disease is tubulointerstitial nephritis, but membranous glomerulonephritis, renal masses, and retroperitoneal fibrosis have also been reported. This concise review has two objectives. First, it will briefly encapsulate the history, epidemiology, and presentation of IgG4-related disease. Second, it will examine the reported renal manifestations of IgG4-related disease, exploring the relevant histology, imaging, clinical features, and treatment considerations. This synthesis will be highly relevant for nephrologists, rheumatologists, general internists, and renal pathologists to raise awareness and help improve early recognition of IgG4-related kidney disease (IgG4-RKD).

Immunoglobulin G4-related disease presenting with nephrotic syndrome due to minimal change disease: a case report

BACKGROUND

Immunoglobulin G4-related disease is an inflammatory disease affecting multiple organs including the kidney. Immunoglobulin G4-related kidney disease most commonly manifests as a tubulointerstitial nephritis and is associated with glomerular disease in a proportion of cases. Membranous nephropathy is the most frequent glomerular lesion. Herein, we report the first documented case of immunoglobulin G4-related disease presenting with nephrotic syndrome owing to minimal change disease.

CASE PRESENTATION

A 67-year-old South Asian male presented to our service with systemic upset and leg swelling. He had heavy proteinuria (urine protein:creatinine ratio 1042 mg/mmol) and was hypoalbuminemic (17 g/L) and hypercholersterolemic (9.3 mmol/L), consistent with the nephrotic syndrome. His serum creatinine was 140 μmol/L, and he was hypocomplementemic (C3 0.59 g/L, C4 < 0.02 g/L) with raised immunoglobulin G4 subclass levels (5.29 g/L). Kidney biopsy demonstrated minimal change disease alongside a plasma-cell-rich tubulointerstitial nephritis with strong positive staining for immunoglobulin G4. A diagnosis of minimal change disease in the setting of immunoglobulin G4-related disease was made. He was commenced on oral prednisolone at 60 mg daily but suffered infectious complications, including necrotizing fasciitis within 3 weeks of starting treatment, ultimately resulting in his death 52 days after initial presentation.

CONCLUSION

This case highlights the potential for immunoglobulin G4-related disease to be associated with a spectrum of glomerular pathologies including minimal change disease. It adds to the differential diagnosis of secondary causes of minimal change disease, and moreover, aids as an important reminder of the potential complications of high-dose steroids used in its treatment.

Relapse and side effects of steroid therapy beyond 3 years in autoimmune pancreatitis: A multicenter retrospective study

BACKGROUND

The impact of extended steroid administration on patients with autoimmune pancreatitis after a 3-year maintenance period remains poorly understood. This study analyzed the advantage and disadvantage of continuing steroid therapy beyond 3 years.

METHODS

In this retrospective multicenter study across 17 institutions, patients who successfully completed 3 years of maintenance therapy without experiencing relapse were categorized into two groups: the maintenance therapy discontinuation group, who discontinued steroid therapy after the initial 3-year period, and maintenance therapy continuation group, who continued steroid therapy beyond 3 years. The cumulative relapse rate after 3 years of maintenance therapy was the primary outcome. Relapse predictors were compared using the Gray test for cumulative relapse incidence by specific factor.

RESULTS

Of 211 patients, 105 experienced no relapse during the 3-year maintenance therapy and were divided into two groups: 69 in the maintenance therapy discontinuation group and 36 in the maintenance therapy continuation group. The relapse rate was lower in the maintenance therapy continuation group than in the maintenance therapy discontinuation group (P = 0.035). Predictors of relapse after 3 years included cessation of maintenance therapy (hazard ratio [HR] = 3.76; 95 % confidence interval [CI] = 1.07-13.3, P = 0.040) and renal involvement (HR = 2.88; 95 % CI = 1.04-7.99, P = 0.042). The maintenance therapy continuation group showed a significantly higher prevalence of macrovascular complications, compared with the maintenance therapy discontinuation group (P = 0.005).

CONCLUSIONS

Cessation of steroid maintenance therapy and renal involvement were predictors of relapse after 3 years of maintenance therapy. However, the long-term use of steroids may increase the risk of macrovascular complications.

Clinical phenotypes and prognosis of IgG4-related diseases accompanied by deteriorated kidney function: a retrospective study

INTRODUCTION

IgG4-related disease (IgG4-RD) is a multiorgan autoimmune disorder that causes irreversible injury. Deteriorated kidney functions are common but easily ignored complications associated with IgG4-RD. Yet the clinical manifestations and prognosis of this specific entity have not been fully illustrated.

METHOD

Three hundred fifty patients with IgG4-RD were retrospectively enrolled and divided into 119 IgG4-RD with chronic kidney disease (IgG4-RD CKD+) and 231 IgG4-RD without CKD (IgG4-RD CKD-). Demographic clinical and laboratory characteristics and survival of two cohorts were compared using restricted cubic splines, logistic and Cox regression, and Kaplan-Meier analysis. A nomogram was generated for calculating the probability of CKD in IgG4-RD.

RESULTS

The spectrum of organ involvement was different between IgG4-RD CKD+ and CKD- cohorts (p<0.001). Lung (26.89%) and retroperitoneum (18.49%) involvement were more common in the IgG4-RD CKD+ cohort. Increased serum potassium and phosphorus, reduced calcium levels, and hypocomplementemia (all p<0.05) were observed in IgG4-RD CKD+. Restricted cubic splines revealed a U-shaped plot regarding associations between serum potassium and CKD. Kaplan-Meier analysis demonstrated significantly lower long-term survival rates in IgG4-RD patients with kidney function at CKD stages 4-5. Cox regression revealed declined kidney functions (G4 HR 6.537 (95% CI: 1.134-37.675)) associated with increased all-cause mortality in IgG4-RD patients. A nomogram was constructed to predict CKD in IgG4-RD promptly with a discrimination (C-index) of 0.846.

CONCLUSIONS

CKD in IgG4-RD was associated with poor outcomes and electrolyte disturbances. Patients with IgG4-RD should be aware of possible deterioration in kidney function. The nomogram proposed would help to identify the subtle possibility of CKD in IgG4-RD. Key points • IgG4-related diseases with deteriorated kidney function have specific clinical and laboratory characteristics. • It is crucial to recognize and address the negative impact of deteriorating kidney function in IgG4-related diseases to prevent further harm. • The nomogram proposed would help to identify subtle kidney involvement by evaluating the possibility of CKD in IgG4-related diseases.

Improved Renal Function in Initial Treatment Improves Patient Survival, Renal Outcomes, and Glucocorticoid-Related Complications in IgG4-Related Kidney Disease in Japan

Introduction

We aimed to clarify long-term renal prognosis, complications of malignancy, glucocorticoid (GC) toxicity, and mortality in immunoglobulin G4 (IgG4)-related kidney disease (IgG4-RKD).

Methods

Reviewing the medical records of 95 patients with IgG4-RKD, we investigated clinical and pathologic features at baseline, the course of renal function, complications of malignancy, GC toxicity, and mortality during follow-up (median 71 months). The standardized incidence ratio (SIR) of malignancy and standardized mortality ratio were calculated using national statistics. Factors related to outcomes were assessed by Cox regression analyses.

Results

At diagnosis, the median estimated glomerular infiltration rate (eGFR) was 46 ml/min per 1.73 m2. GC achieved initial improvement. Additional renal function recovery within 3-months of initial treatment occurred in patients with highly elevated serum IgG and IgG4 levels and hypocomplementemia. During follow-up, 68%, 17%, and 3% of the patients had chronic kidney disease (CKD), >30% eGFR decline, and end-stage renal disease (ESRD), respectively. Age-adjusted and sex-adjusted Cox regression analyses indicated that eGFR (hazard ratio [HR], 0.71) and extensive fibrosis (HR, 2.58) at treatment initiation had a significant impact on the time to CKD. Ten patients died, and the standardized mortality ratio was 0.94. The SIR of malignancy was 1.52. The incidence rate (IR) of severe infection was 1.80/100 person-years. Cox regression analyses showed that the best eGFR within 3 months after treatment initiation were associated with lower mortality (HR 0.67) and fewer severe infections (HR 0.63).

Conclusion

This study suggests that more renal function recovery through early treatment initiation may improve patient survival, renal outcomes, and some GC-related complications in IgG4-RKD.

Enfermedad relacionada con inmunoglobulina G4, un diagnóstico a tener en cuenta: a propósito de un caso

La enfermedad relacionada con inmunoglobulina G4 (ER-IgG4) es una condición inmunomediada y multisistémica asociada al desarrollo de lesiones fibroinflamatorias en cualquier órgano. El diagnóstico se realiza bajo la suma de criterios clínicos, serológicos, radiológicos e histopatológicos; sin embargo, este suele ser difícil debido a su similitud con neoplasias, infecciones u otras enfermedades inmunomediadas. El tratamiento se basa en corticosteroides, en una posible combinación con inmunomoduladores. El presente caso trata de un varón de 59 años con historia de síndrome ictérico y baja de peso, admitido por sospecha de neoplasia maligna de la vía biliar. Las imágenes revelaron estenosis con dilatación de las vías biliares intrahepáticas, páncreas prominente, estenosis del conducto pancreático y lesiones nodulares renales. Debido al antecedente de submandibulectomía izquierda 2 años antes de la enfermedad actual e histología compatible con tumor de Küttner, más los valores elevados de IgG4 sérico, se estableció el diagnóstico de ER-IgG4. Inició tratamiento con corticosteroides y cursó asintomático durante el seguimiento.

Clues to mortality trends and their related factors in IgG4-related disease: A Japanese single-centre retrospective study

OBJECTIVES

This study aimed to clarify mortality trends and their related factors in immunoglobulin G4-related disease (IgG4-RD) with various organ involvement.

METHODS

We retrospectively reviewed the medical records of patients with IgG4-RD at a single rheumatology centre in Japan. We calculated the standardized mortality ratio using Japanese national mortality statistics. Cox regression analyses were also performed to assess mortality-related factors.

RESULTS

A total of 179 patients with IgG4-RD were included with a median follow-up period of 47 months. The standardized mortality ratio in our cohort was 0.86 (95% confidence interval 0.41-1.59). Univariate Cox regression analyses indicated that the number of affected organs at diagnosis (hazard ratio 1.45, 95% confidence interval 1.02-2.05), estimated glomerular infiltration rate <45 ml/min/1.73 m2 at diagnosis (vs. ≥45, hazard ratio 8.48, 95% confidence interval 2.42-29.79), and the presence of malignancy during the clinical course (hazard ratio 5.85, 95% confidence interval 1.62-21.15) had a significant impact on the time to death.

CONCLUSIONS

Our findings suggest that in the rheumatology department, IgG4-RD does not significantly affect long-term patient survival. However, multi-organ involvement, renal dysfunction, and malignancy may be associated with higher mortality trends in IgG4-RD. Early detection and appropriate management of risk factors may improve the long-term prognosis of patients with IgG4-RD.

Case Report: IgG4-related kidney disease complicated by interstitial pneumonia

Immunoglobulin G4 (IgG4)-related disease is a systemic inflammatory disorder characterized by tubulointerstitial nephritis with IgG4-positive plasma cell infiltration. We report the case of an 84-year-old male who presented with a history of dyspnea on exertion and cough. The lymph nodes were palpated in the axilla. Urinalysis revealed mild proteinuria and increased levels of NAG and β2-microglobulin. Blood tests showed hyperglobulinemia with a marked elevation of serum IgG4 levels. Chest computed tomography showed bilateral ground-glass and reticular opacities in the lower and peripheral portions of the lungs. Ga-67 scintigraphy showed kidney uptake. The patient was diagnosed with IgG4-related kidney disease based on the renal pathology indicative of typical tubulointerstitial nephritis with extensive IgG4-positive plasma cell infiltration. The patient was treated with prednisolone and showed a prompt response in his clinical condition. The patient achieved normalization of serum IgG4 levels 6 months after the initiation of treatment. Although IgG4-related disease is thought to be potentially associated with organ fibrosis, there are few reports on combination of interstitial pneumonia and IgG4-related kidney disease. Our case report presents a possible pattern of IgG4-related disease.

Immunoglobulin G4-related Tubulointerstitial Nephritis with Simultaneous Resolution of Plasma Cell Infiltration and Fibrosis after Steroid Treatment

We performed 3 kidney biopsies in a 71-year-old man. At the first biopsy, we made the diagnosis of immunoglobulin G4 (IgG4)-related interstitial nephritis characterized by the simultaneous presence of IgG4-positive plasma cells and characteristic fibrosis with a bird's-eye pattern. At the second biopsy, rather than finding fibrosis as a post-inflammatory scar, we noted that steroid treatment had caused the simultaneous disappearance of IgG4-positive plasma cells and fibrosis and had restored the normal tubular structure. The third biopsy showed the recurrence of the disease with inflammatory cells accompanied by fibrosis. These findings suggest that IgG4-positive plasma cells and fibrosis occur simultaneously.

An uncommon mimicker of renal malignancy: IgG4-related disease

BACKGROUND

Increased usage of cross sectional imaging for a variety of indications, in particular CT imaging, has led to an increased detection of renal and ureteric masses. Benign ureteric masses are rare, with 95% of identified tumours consisting of transitional cell carcinoma (TCC). IgG4-related disease is a recognised clinical systemic autoimmune, inflammatory condition with a propensity for multi-organ manifestation. Nephritis and pseudo-tumour formation can occur when kidneys are involved. Ureteric involvement is more rare.

CASE PRESENTATION

Forty nine-year-old Korean male was found to have an incidental invasive renal pelvis mass during investigation for chronic back pain and fatigue. Appearance of the tumour was consistent with an invasive malignancy, and consensus from multidisciplinary meeting was to have the tumour removed. Procedure involved a prolonged open surgery with reconstruction of contralateral renal blood supply and was complicated by a long recovery process. Final histopathology confirmed IgG4 renal pseudo tumour diagnosis.

CONCLUSION

IgG4-related disease is a rare but potentially morbid disease that can mimic various cancers, including lung, pancreas and renal malignancies. A high index of suspicion is required to accurately diagnose this condition, through a targeted history taking, examination and investigation which should include biopsies. Failing to do so may result in unnecessary procedures being performed and exposing a patient to its associated risks.

Recent advances in IgG4-related kidney disease

Recent advances in the management and understanding of immunoglobulin (Ig)G4-related kidney disease (RKD) have emphasized the importance of urgent treatment in IgG4-related tubulointerstitial nephritis. On the other hand, to avoid long-term glucocorticoid toxicity, strategies for early withdrawal of steroids or combination of immunosuppressants, such as rituximab, and the minimum dose of steroids have been pursued. However, disease recurrence after reducing or stopping steroid therapy hampers early withdrawal of glucocorticoid maintenance therapy. In addition, knowledge has accumulated in diagnostic approaches including differential diagnosis of anti-neutrophil cytoplasmic antibodies-associated vasculitis, idiopathic multicentric Castleman's disease, and Rosai-Dorfman disease with kidney lesion, which leads to earlier and precise diagnosis of IgG4-RKD. This review summarizes recent progress in the differential diagnosis of IgG4-RKD and related treatment strategies and recent topics of hypocomplementaemia, membranous glomerulonephritis, and IgG4-related pyelitis and periureteral lesion.

Perspectives on current and emerging therapies for immunoglobulin G4-related disease

Understanding of the pathophysiology of immunoglobulin G4-related disease (IgG4-RD) over the last dozen years has opened the door to a variety of targeted treatment approaches. Glucocorticoids are an effective treatment for IgG4-RD if used at a sufficiently high dose, but disease flares are common during or after glucocorticoid tapers and these medications seldom lead to long-term, treatment-free remissions. Moreover, their long-term use in a disease that frequently affects middle-aged to elderly individuals and often causes major pancreatic damage leads to a narrow therapeutic index. Biological therapies offer the possibility of effective disease control with fewer treatment-associated side effects. Promising avenues of investigation include B-cell depletion, immunomodulation of B-cell subsets, interference with co-stimulation, Bruton's tyrosine kinase inhibition, and Signaling lymphocytic activation molecule F7-directed treatment.

Development of IgG4-related pancreatitis and kidney disease 7 years after the onset of undiagnosed lymphadenopathy: A case report

This report describes a patient diagnosed with immunoglobulin G4 (IgG4)-related pancreatitis and kidney disease 7 years after the onset of undiagnosed lymphadenopathy. A 48-year-old Japanese woman presented with fatigue and leg oedema. Computed tomography showed perigastric lymphadenopathy, for which she underwent a laparoscopic biopsy of the perigastric lymph nodes. Although histopathological examination of the lymph nodes did not lead to a definitive diagnosis, serological tests revealed elevated serum IgG4 levels (558 mg/dl) and IgG4 immunostaining of the lymph nodes showed IgG4-positive plasma cell infiltration, leading to the suspicion of IgG4-related disease. Further workup revealed no organ lesion other than lymphadenopathy. At age 55 years, despite having no subjective symptoms, contrast-enhanced computed tomography showed low-density lesions in the tail of the pancreas and the left kidney. Histopathological examination showed lymphocyte infiltration, consisting of a mixture of plasma cells and eosinophils, in both organs and obliterative phlebitis in the pancreas. IgG4 immunostaining of the kidney specimens showed 160 IgG4-positive cells per high-powered field, with the IgG4+/IgG+ cell ratio being almost 100%, leading to a diagnosis of IgG4-related pancreatitis and kidney disease. Treatment with prednisolone for 2 months resulted in lesion improvement. Although the diagnosis of IgG4-related lymphadenopathy is often challenging in patients with lymphadenopathy alone, findings in the present patient emphasise the importance of long-term follow-up, as it may allow early detection of involvement of other organs by IgG4-related disease.

T Cell Roles and Activity in Chronic Sclerosing Sialadenitis as IgG4-Related Disease: Current Concepts in Immunopathogenesis

IgG4-related disease is a multiorgan immunological fibroinflammatory disorder characterized by lymphoplasmacytic infiltration and fibrosis in multiple organs accompanied by high serum IgG4 levels. The salivary glands are the most common organs involved in this disease. Recently, chronic sclerosing sialadenitis affecting salivary glands, formerly known as Küttner's tumor, and Mikulicz's disease have been classified as a class of IgG4-related diseases. The etiopathobiology of IgG4-related disease is not fully understood. It has recently been hypothesized that the inflammatory and fibrotic process and the increased serum IgG4⁺ levels in IgG4-related disease are the result of an interaction between B cells and T helper cells, suggesting that T cells may play a key role in the pathogenesis of this disease. The aim of this review is to discuss the proposed roles of different T cell subsets in the pathogenesis of IgG4-related disease focusing on their roles in immunopathogenesis of IgG4-related sialadenitis.

Clinical Characteristics of Patients With IgG4-Related Disease Complicated by Hypocomplementemia

Background

A proportion of patients with immunogloblin G (IgG) 4-related disease (IgG4-RD) have hypocomplementemia. We aimed to identify characteristics of such patients.

Methods

We analyzed the demographic and clinical data and complement levels of 85 patients with IgG4-RD. We defined hypocomplementemia as serum C3 and/or C4 levels below the lower limit of normal at diagnosis. We also compared the characteristics of patients with and without IgG4-RD.

Results

Thirty-two (38%) patients had hypocomplementemia at diagnosis. Patients with hypocomplementemia had more lymph node (p < 0.01), lung (p < 0.01), and kidney (p = 0.02) involvement and a higher IgG4-RD responder index than those without (p = 0.05). Additionally, patients with hypocomplementemia had significantly higher IgG (p < 0.01), IgG4 (p < 0.01), and soluble interleukin 2-receptor (sIL-2R) (p < 0.01) levels and total IgG minus IgG4 (p < 0.01). C3 and C4 levels negatively correlated with IgG, IgG4, and sIL-2R levels, total IgG minus IgG4, and number of IgG4-RD responder index: a measure of the disease activity in IgG4-RD. Patients with hypocomplementemia at diagnosis had a significantly higher frequency of relapse (p = 0.024), as determined using the log-rank test. A multivariate logistic regression analysis showed the presence of hypocomplementemia was independently associated with relapse (OR, 6.842; 95% confidence interval [95%CI], 1.684–27.79; p = 0.007).

Conclusions

Patients with IgG4-RD with hypocomplementemia have a more active clinical phenotype, suggesting contributions of the complement system in the pathophysiology of IgG4-RD.

Persistent enlargement of the pancreatic gland after glucocorticoid therapy increases the risk of relapse in IgG4-related autoimmune pancreatitis

OBJECTIVES

This study aims to clarify the relationship between the changes of pancreatic size after glucocorticoid (GC) therapy and relapse in IgG4-related autoimmune pancreatitis (AIP).

METHODS

We prospectively enrolled 205 newly diagnosed IgG4-related AIP patients. 145 patients were followed up for more than 3 years. These patients were divided into three groups according to the changes of pancreatic size after treatment of 6 months: pancreatic swelling, normal size, and pancreatic atrophy. Baseline clinical and laboratory parameters were compared among three groups. Kaplan-Meier survival analysis was performed in the 134 patients based on GC therapy. Besides, Cox regression analysis and logistic regression analysis were performed to identify risk factors associated with relapse and the potential variables affecting changes of pancreatic size after treatment.

RESULTS

Age at diagnosis, white blood cell count, and serum IgG1 level at baseline were significantly different among the three groups. After treatment of 6 months, the pancreas of most patients (n = 81, 55.9%) could return to normal size, while persistent pancreatic swelling was found in 24.1% patients (n = 35), and atrophy was observed in 20.0% of the patients (n = 29). Kaplan-Meier survival analysis presented patients with pancreatic swelling after 6 months of GC therapy were more likely to relapse in the follow-up of 3 years. Persistent pancreatic swelling after treatment and salivary gland involvement at baseline were independent risk variables associated with relapse in IgG4-related AIP patients, while GC-based therapy was a protective factor of relapse. Logistic regression analysis revealed that older age at diagnosis was associated with pancreatic atrophy and higher baseline serum IgG1 level was associated with pancreatic swelling after treatment of 6 months.

CONCLUSIONS

Patients with persistent pancreatic swelling after GC-based therapy of 6 months were more likely to relapse in the follow-up of 3 years. Older age at diagnosis and higher baseline serum IgG1 level were potential variables associated with pancreatic atrophy or swelling after treatment of 6 months. Key Points • Patients with persistent pancreatic swelling after glucocorticoid-based therapy were more likely to relapse in IgG4-related autoimmune pancreatitis. • Older age at diagnosis was associated with pancreatic atrophy after glucocorticoid-based therapy. • Higher baseline serum IgG1 level was associated pancreatic swelling after glucocorticoid-based therapy.

Unique case of IgG4-related disease of the renal pelvis involving the inferior vena cava masquerading as locally advanced urothelial cancer

Immunoglobulin G4-related disease (IgG4-RD) is a systemic disease which can affect any organ or tissue in the body but most commonly affects the pancreas, biliary ducts, salivary glands, ocular system and lymph nodes; renal involvement is relatively uncommon and there are no previous reported cases of inferior vena cava involvement. Herein, a 48-year-old Asian man with an unremarkable medical history was found to have an obstructing right renal pelvis mass extending to and involving the inferior vena cava, highly suspicious for upper tract urothelial carcinoma that could not be ruled out based on ureteroscopy and urine cytology. Open radical nephroureterectomy with enbloc resection of a segment of the inferior vena cava and left renal vein ostium was performed, with reconstruction of the inferior vena cava and left renal vein with polytetrafluoroethylene grafts. Final histopathology confirmed the diagnosis of IgG4-related disease. This case demonstrates that IgG4-related disease can mimic upper tract urothelial cancer and should be considered as a diagnosis in atypical presentations of tumours of the upper urinary tract.

Update on classification, diagnosis, and management of immunoglobulin G4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a newly recognized chronic fibro-inflammatory autoimmune disease, and its recognition has been constantly increasing worldwide over the last few years. A correct and timely recognition, as well as appropriate intervention, is crucial for the treatment of IgG4-RD. For certain subtypes of IgG4-RD, organ-specific criteria are formulated to make the diagnosis more accurate. New biomarkers have emerged in the recent years to aid the disease diagnosis, its prognosis prediction, as well as therapy response monitoring. Although recurrence is very common in IgG4-RD, glucocorticoid is still the first-line treatment for the majority of patients. The factors that affect the likelihood of disease relapse are multifaceted. The selection strategy of various steroid-sparing agents is still being explored. Besides, when patients have special sites involvement leading to severe clinical conditions, surgical operation or interventional therapy should also be considered. An update on classification, diagnosis, and management of IgG4-RD is provided in the current study to fully elucidate the recommended clinical practice of this mysterious disease.

Renal Involvement in Retroperitoneal Fibrosis: Prevalence, Impact and Management Challenges

Retroperitoneal fibrosis (RPF) is a rare disorder consisting of idiopathic and various secondary forms and characterized by chronic inflammatory infiltrates and marked fibrosis in the retroperitoneal space. In idiopathic RPF (IRPF), 35–60% of cases have been reported to be IgG4-related RPF, the retroperitoneal lesions of IgG4-related disease (IgG4-RD). IRPF can frequently lead to renal insufficiency mediated by urinary tract obstruction and hydronephrosis irrespective of being IgG4-related or not. Clinical pictures, laboratory and imaging findings, and location of the urinary tract obstruction are generally similar in IgG4-related and non-IgG4-related IRPF although multiple organ involvement and serum IgG4 elevation may be characteristic of the IgG4-related forms. Periaortic/periarterial lesions are the most frequent cause of renal insufficiency. Although the response to glucocorticoids is generally good, relapse does occur in a considerable proportion of patients, and may require an additional immunosuppressive agent and/or urological intervention in cases with multiple relapses or refractory obstructive uropathy. In general, the prognosis of patients with IRPF is good, but careful attention needs to be paid to chronic kidney disease as a major complication and rupture of the affected aorta/artery as a life-threatening one. Further studies are necessary to better understand the pathogenesis of the disease and to establish the optimal diagnostic and therapeutic strategies for it.

The prevalence of extra-salivary gland complications in immunoglobulin G4-related sialadenitis

OBJECTIVES

To estimate the prevalence of extra-glandular lesions in patients with immunoglobulin G4-related sialadenitis (IgG4-RS).

METHODS

Six electronic databases (PubMed, EMBASE, Science Direct, Scopus, Web of Science, and China National Knowledge Infrastructure) were systematically searched from the date of inception of each database to March 2021. The Strengthening the Reporting of Observational Studies in Epidemiology statement was used to conduct methodological quality assessment, and a random-effect meta-analysis model was applied to estimate the prevalence. Publication bias was visually assessed using a funnel plot and calculated via Begg's and Egger's tests. The Stata 15 software was used to perform data analysis.

RESULTS

A total of 43 articles comprising 1,864 patients with IgG4-RS were considered to be eligible for this study. The pooled prevalence of extra-salivary gland lesions in IgG4-RS was 76.53% with a confidence interval (CI) of (69.39%, 83.04%). A higher prevalence was associated with studies published before or during 2015 (84.38%, CI [74.23%, 92.58%]) than those published after 2015 (68.55%, CI [58.44%, 77.88%]). Lacrimal gland involvement (54.68%, CI [45.61%, 63.60%]) and lymph node swelling (56.96%, CI [48.16%, 65.56%]) were the most frequent lesions.

CONCLUSIONS

Extra-glandular lesions were common in patients with IgG4-RS. More high-quality prospective studies with less heterogeneity are required to determine the accurate prevalence.

Renal Involvement in IgG4-Related Disease: From Sunlight to Twilight

IgG4-Related Disease (IgG4-RD) is a fibroinflammatory condition characterized by a typical histopathological pattern (dense lymphoplasmacytic infiltrate with prevalent IgG4+ plasma cells and storiform fibrosis), which may involve the kidney both directly (IgG4-related kidney disease, IgG4-RKD) or indirectly, as a consequence of post-renal ureteral obstruction due to retroperitoneal fibrosis (IgG4-RD RF). The most frequent presentation of IgG4-RKD is IgG4-related tubulointerstitial nephritis (TIN), but a glomerular disease can be present, in most of the cases a membranous nephropathy. Albeit steroid-responsive, in some cases renal manifestations may lead to progressive and permanent organ damage. In this review we describe four clinical cases representative of typical and less typical renal manifestations of IgG4-RD, emphasizing a potential, subclinical, early involvement of the kidney in the disease.

Tertiary lymphoid tissue in early-stage IgG4-related tubulointerstitial nephritis incidentally detected with a tumor lesion of the ureteropelvic junction: a case report

Background

IgG4-related kidney disease causes renal impairment of unknown pathogenesis that may progress to kidney failure. Although ectopic germinal centers contribute to the pathogenesis of the head and neck lesions of IgG4-related disease, the presence of tertiary lymphoid tissue (TLT) containing germinal centers in IgG4-RKD has rarely been reported.

Case presentation

We report a 72-year-old Japanese man who had IgG4-related tubulointerstitial nephritis (TIN) with TLT formation incidentally detected in a resected kidney with mass lesion of IgG4-related ureteritis in the ureteropelvic junction. During follow-up for past surgical resection of a bladder tumor, renal dysfunction developed and a ureter mass was found in the right ureteropelvic junction, which was treated by nephroureterectomy after chemotherapy. Pathology revealed no malignancy but abundant IgG4-positive cell infiltration, obliterative phlebitis and storiform fibrosis, confirming the diagnosis of IgG4-related ureteritis. In the resected right kidney, lymphoplasmacytes infiltrated the interstitium with focal distribution in the renal subcapsule and around medium vessels without storiform fibrosis, suggesting the very early stage of IgG4-TIN. Lymphocyte aggregates were also detected at these sites and consisted of B, T, and follicular dendritic cells, indicating TLT formation. IgG4-positive cells infiltrated around TLTs.

Conclusions

Our case suggests that TLT formation is related with the development of IgG4-TIN and our analysis of distribution of TLT have possibility to elucidate IgG4-TIN pathophysiology.

Infiltrative Renal Malignancies: Imaging Features, Prognostic Implications, and Mimics

Infiltrative renal malignancies are a subset of renal masses that are morphologically characterized by a poorly defined interface with the renal parenchyma. Infiltrative renal malignancies are less common but more aggressive than more typical renal malignancies and carry an overall worse prognosis. Although an infiltrative renal process often represents a malignant neoplasm, infiltrative masses include a wide spectrum of diseases including primary renal cortical, medullary, and pelvic tumors; lymphoproliferative processes; metastases; and various infectious, inflammatory, immune-mediated, and vascular mimics. The imaging features of these masses are often nonspecific, but with the appropriate history, laboratory results, and clinical context, the radiologist can help narrow the diagnosis and guide further treatment. An invited commentary by Lee is available online.Online supplemental material is available for this article. ^©RSNA, 2021.

IgG4-related nephritis and interstitial pulmonary disease complicated by invasive pulmonary fungal infection: a case report

Background

IgG4-related kidney disease (IgG4-RKD) can affect multiple organs, which was first reported as a complication or extra-organ manifestation of autoimmune pancreatitis in 2004. It is characterized by abundant IgG4-positive plasma cells infiltration in tissues involved.

Case presentation

A 69-year-old man presented with cough and renal dysfunction with medical history of hypertension and diabetes. Pathological findings revealed interstitial nephritis and he was initially diagnosed with IgG4-RKD. Prednisone helped the patient to get a remission of cough and an obvious decrease of IgG4 level. However, he developed invasive pulmonary fungal infection while steroid theatment. Anti-fungal therapy was initiated after lung puncture (around cavitary lung lesion). Hemodialysis had been conducted because of renal failure and he got rid of it 2 months later. Methylprednisolone was decreased to 8 mg/day for maintenance therapy. Anti-fungal infection continued for 4 months after discharge home. On the 4th month of follow-up, Chest CT revealed no progression of lung lesions.

Conclusions

The corticosteroids are the first-line therapy of IgG4-RD and a rapid response helps to confirm the diagnosis. This case should inspire clinicians to identify IgG4-related lung disease and secondary pulmonary infection, pay attention to the complications during immunosuppressive therapy for primary disease control.

Prognostic factors in IgG4-related disease: a long-term monocentric Chinese cohort study

OBJECTIVES

Patients with IgG4-related disease (IgG4-RD) suffer high relapse rates during long-term treatment, but factors that predict relapse outcomes are not well established. In the present study, we aimed to identify predictive factors for treatment resistance and disease relapse in a Chinese IgG4-RD cohort.

METHODS

This study enrolled 102 patients newly diagnosed with IgG4-RD. Disease prognosis was determined by evaluating disease activity and dosage of glucocorticoids. Predictive factors for refractory and relapsed disease were identified by univariate analysis and Cox regression.

RESULTS

Among the 102 patients, 78 cases received medical treatment with regular follow-up (21 [6-111] months). During the follow-up period, 55 (70.5%) patients sustained clinical remission, and 23 (29.5%) patients suffered refractory or relapsed disease. The relapse rate of the patients with IgG4-RD was significantly higher among patients who stopped taking medicine than among those who continued treatment with glucocorticoids (GC) + immunosuppressor (IM). Serum TNF-α ≥ 13 pg/mL, sIL-2R ≥ 1010 U/mL, total cholesterol < 3.55 mmol/L, low-density lipoprotein < 2.0 mmol/L, IgG ≥ 20.2 g/L, and drug withdrawal were predictive factors for refractory and relapsed IgG4-RD. Multivariate Cox regression revealed that both sIL-2R and TNF-α were independent risk factors for refractory and relapsed disease. The combination of GC and IM treatment was an independent protective factor against refractory and relapsed IgG4-RD.

CONCLUSIONS

High serum levels of sIL-2R and TNF-α may be informative risk factors for refractory and relapsed IgG4-RD. Our data suggest that a combination treatment of GC along with IM may be protective against refractory and relapsed IgG4-RD. Key Points • High sIL-2R and TNF-α levels are informative risk factors for refractory and relapsed IgG4-related disease. • Combination treatment of GC with IM protects against refractory and relapsed IgG4-related disease.

Long-term changes in renal function after treatment initiation and the importance of early diagnosis in maintaining renal function among IgG4-related tubulointerstitial nephritis patients in Japan

BACKGROUND

The present study aimed to investigate associations between long-term renal function, whether IgG4-related tubulointerstitial nephritis (TIN) was diagnosed by renal biopsy at initial examination, chronic kidney disease (CKD) stage, and histological stage in patients with IgG4-related TIN.

METHODS

This study used a retrospective cohort design including almost all patients who underwent renal biopsy at Fujita Health University Hospital and Nagoya University or its affiliated hospitals in Aichi between April 2003 and March 2015 (n = 6977 renal biopsies). The primary outcome was longitudinal changes in eGFR. Main exposures were whether IgG4-related TIN was diagnosed by renal biopsy at the initial examination, CKD stage, and its histological stage. Linear mixed models were performed to examine associations.

RESULTS

Of the 6977 samples, there were 24 patients (with 201 records due to repeated measures) with IgG4-related TIN (20 men, mean age, 68.7 ± 9.7 years). They were followed up 6.6 ± 2.8 years after the renal biopsy and underwent glucocorticoid treatment. We found significant increase in eGFR from the baseline to 2 and 6 months after treatment initiation, which was maintained until 60 months. Patients initially diagnosed with IgG4-related TIN had higher eGFR from the baseline (at the start of treatment) to 60 months than those who were not. Compared with patients with CKD stage 3, patients with CKD stages 4 and 5 had lower eGFR at the baseline and other time points. Patients with histological stage B had comparatively lower eGFR at each point than stage A patients. Those mean differences of eGFR were stable from the baseline to 60 months.

CONCLUSIONS

After the treatment initiation, renal function rapidly improved and maintained for a long period, even with advanced CKD stage. We showed importance of early diagnosis of IgG4-related TIN in maintaining eGFR.

Idiopathic membranous nephropathy in a patient diagnosed with IgG4-related disease: A case report

RATIONALE

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is a newly recognized, systemic disease. Membranous nephropathy is the most common glomerular lesion in IgG4- related kidney disease. However, the lack of relationship with IgG4-related kidney disease and monoclonal gammopathy of undetermined significance (MGUS) warrants investigation of the potential mechanisms.

PATIENT CONCERNS

A 62-year-old patient was diagnosed with IgG4-RD, tubulointerstitial nephritis, retroperitoneal fibrosis. After 2 years, she was presented with proteinuria, hypoproteinemia, facial, and bilateral lower limb edema. Furthermore, this patient exhibited deposits of IgG k of monoclonal hyperplasia, and bone marrow plasma cell count was 2.5%.

DIAGNOSIS

The patient was diagnosed with nephrotic syndrome, acute kidney injury, and MGUS. The pathological diagnosis was IgG4-related tubulointerstitial nephritis, IgG4-related membranous nephropathy.

INTERVENTIONS

The patient was treated with intravenous methylprednisolone (40 mg daily), which was changed to oral prednisone 50 mg/d after 2 months.

OUTCOMES

After 1 month, the patient exhibited a rapid response only with corticosteroid, and experienced partial remission of serum albumin and proteinuria.

LESSONS

This case may suggest a possible relationship between IgG4-RD and MGUS, provide some guidance for investigating the mechanism between them.

IgG4-related lung disease progressing to respiratory failure

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is a systemic immune-mediated, fibroinflammatory disorder categorized as proliferative or fibrotic depending on the responsiveness of corticosteroid treatment. IgG4-related lung disease (IgG4-RLD) accounts for 13-14% of IgG4-RD cases, but respiratory failure is quite rare. A 71-year-old man diagnosed with interstitial lung disease was referred to our department after a 10-month observational period. He presented with respiratory failure at the first visit, with significant elevations in serum IgG4 levels and histopathological findings meeting the criteria of IgG4-positive plasma cells and IgG4/IgG-positive plasma cell ratio in transbronchial lung biopsy and inguinal lymph node biopsy, resulting in a diagnosis of IgG4-RD. Systemic corticosteroid treatment promptly ameliorated the respiratory failure. 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography showed significant FDG accumulation in the lung fields, indicating the proliferative and reversible status of IgG4-RLD, which responded well to corticosteroid treatment. The patient recovered from respiratory failure even after a 10-month observational period.

Immunoglobulin G4-related Disease of the Genitourinary System: Spectrum of Imaging Findings and Clinical-Pathologic Features

Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory disease characterized by focal or diffuse organ infiltration of IgG4-bearing plasma cells. The diagnosis of IgG4-RD is based on a combination of clinical, serologic, radiologic, and histopathologic findings. IgG4-RD has been reported to affect almost all organ systems. The kidney is the most frequently involved of the genitourinary organs. The most common renal manifestation of IgG4-RD is IgG4-RD tubulointerstitial nephritis, followed by membranous glomerulonephropathy and, less frequently, obstructive nephropathy involving the renal pelvis, ureter, or retroperitoneum. Renal parenchymal lesions may appear as multiple nodular lesions, diffuse patchy infiltrative lesions, or a single nodular lesion. Multiple small nodular cortical lesions are the most common imaging findings of IgG4-RD involving the kidney. Renal pelvic, sinus, or perinephric lesions can also occur. IgG4-RD involvement of other genitourinary organs including the ureter, bladder, urethra, and male and female reproductive organs is rare compared with kidney involvement but may show variable imaging findings such as a localized mass within or surrounding the involved organ or diffuse enlargement of the involved organ. Imaging findings of IgG4-RD involving the genitourinary system are nonspecific but should be differentiated from inflammatory and neoplastic lesions that mimic IgG4-RD. The online slide presentation from the RSNA Annual Meeting is available for this article. ^©RSNA, 2020.

IgG4-related disease in the abdomen and pelvis: atypical findings, pitfalls, and mimics

IgG4-related disease (IgG4-RD) is a systemic, autoimmune, fibroinflammatory disease that can cause multi-organ damage. Although there have been many trials and studies since its recognition in 2003, there is still much that is unknown. Furthermore, IgG4-RD can affect any organ in the body and often has many mimics and alternative diagnoses, which can make for a challenging workup. Imaging plays a substantial role in the diagnosis of IgG4-RD and is often the first occasion where IgG4-RD comes into consideration. Thus, knowledge about the imaging findings of various manifestations of IgG4-RD can aid in the diagnosis and have a significant impact on patient management. In this article, we review the wide array of imaging findings, both typical and atypical, as well as possible mimics of IgG4-RD in the abdomen and pelvis.

IgG4-related disease: a clinical perspective

IgG4-related disease (IgG4-RD) is a recently recognized fibro-inflammatory disorder that can affect almost any organ. Common presentations include major salivary and lacrimal gland enlargement, orbital disease, autoimmune pancreatitis, retroperitoneal fibrosis and tubulointerstitial nephritis. The main histopathological features are a dense, polyclonal, lymphoplasmacytic infiltrate rich in IgG4+ plasma cells, storiform fibrosis and obliterative phlebitis. The precise pathogenic mechanisms of IgG4-RD are still unclear. CD4+ T and B cells, including IgG4-expressing plasmablasts, constitute the major inflammatory cell populations and are believed to cause organ damage and tissue fibrosis. The diagnosis of the disease may be challenging and should be based on specific histopathological findings, typical laboratory and radiological aspects and an appropriate clinical context. The first-line treatment of IgG4-RD is based on glucocorticoids, which are usually efficacious. However, B cell depletion induced by rituximab has also been found to induce remission in steroid-resistant disease or has been used as steroid-sparing agent for relapsing disease. This review provides an update on clinical and therapeutic aspects of IgG4-RD.

Abundant a proliferation-inducing ligand (APRIL)-producing macrophages contribute to plasma cell accumulation in immunoglobulin G4-related disease

Background

This study aimed to investigate the contribution of a proliferation-inducing ligand (APRIL), a member of the tumor necrosis factor (TNF) superfamily implicated in plasma cell survival, to the development of plasma cell–rich lesions in immunoglobulin G4–related disease (IgG4-RD).

Methods

We performed immunohistochemical staining for APRIL with Stalk-1 and Aprily-8 antibodies specifically recognizing APRIL-producing cells and secreted APRIL, respectively, in renal and submandibular lesions of IgG4-RD in comparison with those of Sjögren’s syndrome and sialolithiasis.

Results

Numerous Stalk-1-positive APRIL-producing cells were detectable in lesions of IgG4-RD. These cells, identified as CD163-positive M2 macrophages, secreted APRIL that distributed close to and even on infiltrating plasma cells. In contrast, APRIL-producing cells and the secreted form of APRIL were rarely detectable in lesions of Sjögren’s syndrome or sialolithiasis. Notably, APRIL expression decreased concomitantly with the level of plasma cell infiltration after successful glucocorticoid treatment.

Conclusions

Abundant infiltration into tissue lesions of APRIL-producing M2 macrophages and retention of secreted APRIL in plasma–cell–rich areas support a role for APRIL in the pathogenesis of plasma cell–rich lesions in IgG4-RD.

Renal involvement in IgG4-related disease

IgG4-RD may affect several organs including kidneys. The kidney is involved in approximately 20% of patient with IgG4-RD. The most common intrinsic kidney disease is tubulointerstitial nephritis (IgG4-TIN). Retroperitoneal fibrosis (IgG4-RPF) may induce obstructive acute renal failure. More rarely, IgG4-RKD can manifest as a glomerular disease, in particular as a membranous nephropathy (MN). It mostly affects middle-aged to elderly men and causes acute or chronic renal dysfunction, multiple hypodense lesions on CT-Scan and various extra-renal lesions. Increased serum IgG4 and hypocomplementemia are the most important serological findings for the diagnosis of IgG4-RD and thus should be systematically assessed when IgG4-RKD is suspected. Specific diagnosis criteria for IgG4-TIN including interstitial infiltration of IgG4-positive plasma cells, storiform fibrosis and tubular basement membrane immune complex deposits have been proposed. Corticosteroids are effective and remain the first-line therapy but relapses or severe forms could respond to immunosuppressive therapy.

IgG4-Related Disease Manifesting as Hypocomplementemic Tubulointerstitial Nephritis: A Rare Case Report and Literature Review

Immunoglobulin G4-related disease (IgG4-RD) is a chronic fibrosing inflammatory systemic disorder that has been recognized relatively recently in the medical literature. Little is known about the exact disease pathogenesis and epidemiology. IgG4-RD may be asymptomatic or may have minimal symptoms or involve multiple organs with overt symptoms. The different phenotypes of IgG4-RD can lead to delayed or incorrect diagnosis. We report the case of a 66-year-old male with coal worker's pneumoconiosis who presented with progressive kidney disease and was diagnosed with tubulointerstitial nephritis due to IgG4-RD. The patient was noted to have progressive kidney disease, skin involvement, worsening interstitial lung disease, complete vision loss in the left eye, and retroperitoneal fibrosis. Serologic workup revealed elevated inflammatory markers, IgG4 and IgG1 levels, and hypocomplementemia. A tissue biopsy helped us establish a definitive diagnosis of IgG4-RD and initiate treatment with glucocorticoids to prevent further progression of kidney disease and other end-organ damage.

Acute Tubulointerstitial Nephritis as a Sole Manifestation of Immunoglobulin G4-Related Disease

This is a case report of a patient who developed severe acute kidney disease with kidney biopsy showing interstitial nephritis, plasma cell infiltration and immunoglobulin G4 (IgG4) expression consistent with IgG4-related kidney disease. There were no other systemic features of IgG4-related disease. The patient was treated with corticosteroids and mycophenolate. This case highlights the need to consider IgG4-related kidney disease even in the absence of other systemic features. Isolated renal involvement is underrecognized and can lead to missed diagnosis. It also illustrates that mycophenolate can be used as a steroid sparing agent in this condition; an observation that adds to the limited literature in this field.

Clinical characteristics of autoimmune pancreatitis with IgG4 related kidney disease

PURPOSE

To clarify the clinical characteristics of autoimmune pancreatitis (AIP) in immunoglobulin (Ig)G4-related kidney disease (IgG4-RKD).

PATIENTS AND METHODS

A total of 92 patients with AIP were divided into an IgG4-RKD-positive group (RKD-P group, n = 13) and an IgG4-RKD-negative group (RKD-N group, n = 79) on the basis of the diagnostic criteria for IgG4-RKD. Clinical characteristics, including: age; sex; the presence of extrapancreatic lesions other than renal lesions, proteinuria, and hematuria; serum concentrations of IgG, IgG4, IgE, and creatinine; and urinary concentrations of liver-type fatty acid binding protein, α1-microglobulin, β2-microglobulin, and N-acetyl-β-d-glucosaminidase were compared between the RKD-P and RKD-N groups. The clinical course of the RKD-P group was also characterized.

RESULTS

The prevalence of extrapancreatic lesions other than renal lesions was significantly higher in the RKD-P group (84.6% vs 43.0%,p < 0.01). Serum creatinine (1.19 mg/dl versus 0.74 mg/dl, p < 0.05), urinary β2-microglobulin (6609.8 μg/l vs 265.8 μg/l, p < 0.05), and the prevalence of proteinuria (30.7% vs 7.6%, p < 0.05) were significantly higher in the RKD-P group. Nine out of thirteen patients in the RKD-P group had multiple low-density renal lesions on enhanced computed tomography, 3 patients had multiple high-intensity lesions on diffusion-weighted magnetic resonance images, and 1 patient had diffuse thickening of the renal wall, with a smooth intra-luminal surface.

CONCLUSIONS

Patients who had AIP with IgG4-RKD were more likely to have extrapancreatic lesions other than those in the kidney, and their serum creatinine and urinary β2-microglobulin concentrations were significantly higher than in those without IgG4-RKD.

PLA2R-Negative Membranous Nephropathy Presenting as a Prodrome of IgG4-Related Autoimmune Pancreatitis

Membranous nephropathy (MN) with tubulointerstitial nephritis (TIN) is an established manifestation of immunoglobulin G4 (IgG4)-related disease (IgG4-RD). A pathological feature aiming to distinguish between primary and secondary MN is the presence or absence of glomerular staining for phospholipase A2 receptor (PLA2R), respectively. Isolated MN without TIN has been rarely reported in the context of IgG4-RD. This case report describes a patient with a history of MN successfully treated with steroids and cyclophosphamide, who, 3 years later, presented with unexplained exacerbation of diabetes mellitus due to IgG4-related autoimmune pancreatitis. Pancreatitis was treated, and diabetes improved after treatment with steroids. Based on the presence of isolated IgG4 glomerular capillary deposits along with negative staining for PLA2R and the metachronous appearance of autoimmune pancreatitis, MN was retrospectively classified as secondary to IgG4-RD. Isolated IgG4-positive/PLA2R-negative MN without TIN can be a prodrome of IgG4-RD, reminiscent of MN secondary to neoplasms.

Clinical strategies for differentiating IgG4-related cholecystitis from gallbladder carcinoma to avoid unnecessary surgical resection

Immunoglobulin G4 (IgG4)-related cholecystitis (IgG4-C) is often difficult to distinguish from gallbladder carcinoma (GBC). This study aimed to determine a practical strategy for differentiating between IgG4-C and GBC to avoid unnecessary surgical resection. The expression of IgG4 in the gallbladder was detected by immunohistochemistry. The clinicopathological and radiological characteristics of IgG4-C patients and GBC patients were analyzed retrospectively. Immunohistochemistry revealed that IgG4 was upregulated in the plasma cells of IgG4-C tissues. The median serum total bilirubin levels were significantly higher in the patients with IgG4-C than in those with GBC (45.8 µmol L^-1 vs. 29.9 µmol L^-1). The serum γ-GGT levels were higher in IgG4-C patients than in GBC patients, whereas the serum levels of CA125 were significantly higher in GBC patients than in IgG4-C patients. The imaging scans were helpful for differentiating IgG4-C from GBC based on the presence of a layered pattern and Rokitansky-Aschoff sinuses in the gallbladder wall. There were no statistically significant differences in age, presence of abdominal pain, level of emaciation between the two groups. Our study demonstrated that the combination of imaging with serum total bilirubin, γ-GGT and CA125 levels can offer added preoperative diagnostic value and reduce the rate of IgG4-C misdiagnosis.

Risk factors and treatment of relapses in autoimmune pancreatitis: Rituximab is safe and effective

Background and aims

Steroid therapy is the first-line treatment for autoimmune pancreatitis but relapses are frequent. The aims were to assess the efficacy and the safety of immunomodulator treatments for relapsing autoimmune pancreatitis and rituximab in particular and to identify relapsing risk factors.

Methods

Patients followed for autoimmune pancreatitis from 2000 to 2016 were included. Data were retrospectively analysed regarding autoimmune pancreatitis treatment.

Results

In total, 162 patients with autoimmune pancreatitis type 1 (n = 92) and type 2 (n = 70) were included (median follow-up: 3 years (0.5-14). Relapse occurred in 46.5% of patients with autoimmune pancreatitis type 1 (vs 19.3% in autoimmune pancreatitis 2; p < 0.001). Risk factors of relapse were cholangitis, initial use of steroids, other organ involvement and chronic pancreatitis in autoimmune pancreatitis type 1 and initial use of steroids, tobacco consumption and chronic pancreatitis for autoimmune pancreatitis type 2. Overall, 21 patients were treated with immunomodulators (azathioprine, n = 19, or methotrexate, n = 2) for relapses. The efficiency rate was 67%. A total of 17 patients were treated with rituximab, with two perfusions at 15 days apart. The efficacy was 94% (16/17), significantly better than immunomodulator drugs (p = 0.03), with a median follow-up of 20 months (11-44). Only two patients needed two supplementary perfusions.

Conclusion

In relapsing autoimmune pancreatitis, rituximab is more efficient than immunomodulator drugs and shows better tolerance.

Biomarkers in IgG4-related disease: A systematic review

OBJECTIVE

ImmunoglobulinG4-related disease (IgG4-RD) is a recently recognized disease and, as such, there is a pressing need to identify biomarkers for diagnosis, monitoring disease activity, and predicting prognosis and response to therapy. Here, we review the recent development and identification of biomarkers for IgG4-RD.

METHODS

Through extensive literature review and analysis, we updated the biomarkers for IgG4-RD and further put forward our own viewpoints.

RESULTS

In addition to traditional biomarkers, such as serum IgG4 concentration and typical histological characteristics, several novel indicators, including IgG2, serum soluble IL-2 receptor (sIL2R), and cc-chemokine ligand 18 (CCL18), indicate inflammation and fibrosis and can be used to accurately diagnose and predict treatment response. Studies to identify target autoantigens in IgG4-RD have shed light on the unmet need for biomarkers that can identify this disorder. Additionally, both serological and histopathologic immune cells involved in antigen-induced responses, innate immune cells (macrophages, mast cells, and the I-IFN/ IL-33 pathway), as well as subsequent acquired immune cells (T and B cell subsets), may also serve as new biomarkers for IgG4-RD. Since IgG4-RD often clinically manifests with multiple organs involvement, non-invasive PET-CT can improve diagnosis and antidiastole levels.

CONCLUSION

These novel biomarkers provide information to help diagnose IgG4-RD, monitor disease activity, as well as predict prognosis and response to therapy.

IgG4-Related Disease with Emphasis on Its Gastrointestinal Manifestation

IgG4-related disease is an immune-mediated fibroinflammatory condition with a diverse spectrum of organ involvement, commonly in the pancreas and bile ducts among other organs such as salivary and lacrimal glands. Classic histopathologic findings are the gold standard for confirmation of diagnosis, although diagnosis remains challenging, as biomarkers to date are neither sufficient nor necessary. Glucocorticoids are the most effective initial treatment, generally having a dramatic response, although limited clinical evidence exists regarding effective maintenance therapy. This review summarizes key GI manifestations of this condition for the practicing gastroenterologist and addresses the pathology, disease mechanism, and current therapeutic recommendations.

Imaging features of immune-mediated genitourinary disease

PURPOSE

Imaging features of immune-mediated genitourinary diseases often overlap, and the same disease may manifest in different ways, so understanding imaging findings in the context of the patient's entire clinical picture is important in providing the correct diagnosis.

METHODS

In this article, diseases mediated by the immune system which affect the genitourinary system are reviewed. Examples of immune-mediated genitourinary disease including IgG4-related disease, post-transplant lymphoproliferative disorder, immunodeficiency-associated lymphoproliferative disorder due to immunosuppressive and immunomodulatory medications, lymphoma, leukemia, myeloma, amyloidosis, and histiocytosis.

RESULTS

Clinical and imaging features will be presented which may help narrow the differential diagnosis for each disease.

CONCLUSION

Recognition of immune-related genitourinary disease is important for appropriate medical management as they may mimic other diseases both by imaging and clinical presentation.

Advances in IgG4-related pancreatobiliary diseases

Autoimmune pancreatitis is an unusual form of pancreatitis that is histologically characterised by a massive infiltration of lymphocytes and IgG4-positive plasma cells and storiform fibrosis. The disease is recognised as a pancreatic manifestation of IgG4-related disease. IgG4-related sclerosing cholangitis is a biliary counterpart that is typically associated with autoimmune pancreatitis. Two parallel immunological responses are thought to underlie the pathophysiology of these diseases: a pro-inflammatory, tissue-destructive process and an anti-inflammatory feedback response, which probably relates to IgG4 production. These diseases should be differentiated from conditions with a similar presentation (eg, pancreatobiliary malignancy, primary sclerosing cholangitis) by comparison of serum IgG4 concentration, imaging features, other organ involvement, histology, and steroid responsiveness. Corticosteroids are first-line drugs, although rituximab has been shown to effectively deplete B cells in IgG4-related disease. Although the risk of relapse is high, no standardised treatment protocol exists for relapsed cases.

Progressive Renal Dysfunction due to IgG4-Related Kidney Disease Refractory to Steroid Therapy: A Case Report

Recently, as the number of case reports of IgG4-related kidney disease (IgG4-RKD) has increased, the histopathological features and clinical approach have been clarified. IgG4-RKD generally has a benign prognosis due to the efficacy of steroid therapy and rarely requires dialysis. Herein, we report a case of IgG4-RKD that presented with a subacute onset, advanced to end-stage kidney disease, and finally required maintenance hemodialysis despite steroid therapy. A 75-year-old man was admitted to our hospital for further evaluation of subacute renal failure. Diffuse enlargement of the kidney on computed tomography and increased urinary N-acetyl-β-D-glucosaminidase and α1-microglobulin levels led us to suspect IgG4-RKD. Upon admission, the laboratory serological findings were as follows: creatinine 3.3 mg/dL, urea nitrogen 46.9 mg/dL, and IgG4 235 mg/dL. Urinalysis showed slight proteinuria without hematuria. Percutaneous renal needle biopsy showed diffuse infiltration of abundant lymphocytes and IgG4-positive plasma cells and storiform fibrosis, which is specific to IgG4-RKD, in the interstitium on light microscopy. Slight linear deposition of C3 was also observed in the tubules on immunofluorescence microscopy, with no electron-dense deposits. He was definitively diagnosed as having IgG4-RKD and started on prednisolone 0.6 mg/kg/day. However, the renal insufficiency continued to progress and hemodialysis was necessary. As the prednisolone was tapered, renal function did not improve and maintenance hemodialysis was started. In conclusion, this case indicates that the prognosis of IgG4-RKD is not necessarily benign and that further studies involving more patients are needed.

Clinical Manifestations and Long-term Outcomes of IgG4-Related Kidney and Retroperitoneal Involvement in a United Kingdom IgG4-Related Disease Cohort

INTRODUCTION

IgG4-related disease (IgG4-RD) is a relapsing multisystem fibro-inflammatory disease, which may involve the kidney (IgG4-related kidney disease [IgG4-RKD]) and retroperitoneum (IgG4-related retroperitoneal fibrosis [IgG4-RPF]). The aim of this study was to describe IgG4-RKD and IgG4-RPF in the United Kingdom.

METHODS

We conducted a retrospective observational study of patients with IgG4-RKD and IgG4-RPF in a multicenter IgG4-RD cohort. Data were collected through review of medical records. We describe clinical parameters at baseline, histological and radiological findings, treatment, and patient outcomes.

RESULTS

Of 154 patients with IgG4-RD, 14 (9.1%) had IgG4-RKD, 10 (6.5%) had IgG4-RPF, and 4 (2.6%) had both. Patients were aged 58.2 ± 14.2 years, and 26 (92.9%) were male. Creatinine at presentation was worse in those with intrinsic renal disease (229 μmol/l vs. 110 μmol/l; P = 0.0076). Serum IgG4 was elevated in the majority of patients (87.5%), and hypocomplementemia was present in half of those with IgG4-RKD. Fifteen patients underwent renal biopsy; tubulointerstitial nephritis with abundant IgG4+ plasma cells was the most common finding (n = 14; 93.3%), and 4 (26.7%) patients had membranous nephropathy. Most patients (89.3%) were treated with corticosteroids, and 4 (16.0%) with additional azathioprine as initial management. Thirteen patients (46.4%) relapsed over 60 ± 48 months of follow-up, at median 18 (12-36) months after renal/RPF diagnosis; 61.5% of relapses were in the kidney. Renal function deteriorated in 5 patients (20.8%), including 2 (8.3%) who reached end-stage renal disease (ESRD).

CONCLUSION

IgG4-RKD and IgG4-RPF represent major organ manifestations of IgG4-RD, and should be identified early with prompt treatment to prevent progression to ESRD.