IgG4-Related Disease: Clinical and Laboratory Features in One Hundred Twenty-Five Patients

IgG4-related disease revealed by acute pancreatitis: A case report and literature review

IgG4-related disease is a systemic autoimmune disorder characterized by multiorgan involvement, often presenting with pancreatic, renal, biliary, and salivary gland abnormalities. Diagnosis relies on clinical, serological, imaging, and occasionally histological findings. This report describes a 65-year-old male presenting with acute pancreatitis, bilateral renal lesions, and biliary strictures. Elevated serum IgG4 levels (3.76 g/L) confirmed the diagnosis using the 2019 ACR/EULAR and 2020 Comprehensive Diagnostic Criteria despite the lack of histological confirmation. Corticosteroid therapy led to rapid clinical and biochemical improvement, underscoring the importance of integrating multiple diagnostic modalities in managing IgG4-related disease and demonstrating the effectiveness of early intervention.

IgG4-related disease and other fibro-inflammatory conditions

IgG4-related disease (IgG4-RD) is a fibro-inflammatory disorder usually characterized by multi-organ involvement. Its pathogenesis is complex and involves genetic and environmental factors, while immune responses usually mediate organ damage and promote fibrosis, which is a key feature of the disease. IgG4 responses, however, are not exclusive to IgG4-RD and can be encountered in other diseases with phenotypes that partially overlap that of IgG4-RD. Although IgG4-RD has clinical and histological hallmarks, the lack of validated diagnostic criteria often makes the diagnosis challenging, requiring a multi-dimensional approach that integrates clinical, radiological and serological data. The present Review covers recent advances in the understanding of disease drivers and its clinical phenotypes, mainly focusing on the differential diagnosis with potential IgG4-RD mimickers, namely histiocytoses, lymphoproliferative disorders, systemic vasculitides and other immune-mediated conditions. The Review also provides a schematic approach to IgG4-RD treatment, including a brief overview of glucocorticoid-sparing agents and emerging therapies, from B cell-depleting monoclonal antibodies to cytokine-targeting drugs, the majority of which are currently under investigation in randomized clinical trials.

IgG4-Related Disease (IgG4-RD) Autoimmune Pancreatitis (AIP) as an Initial Presentation of Systemic Lupus Erythematosus (SLE)

Acute pancreatitis stemming from IgG4-Related Disease (IgG4-RD) seldom coincides with Systemic Lupus Erythematosus (SLE), highlighting the importance of investigating autoimmune conditions in patients with IgG4-RD. We present the case of a 57-year-old male with a medical history notable for hypertension, photosensitivity, arthritis, and malar rash, who presented with 6 weeks of persistent epigastric pain. Computed Tomography (CT) of the abdomen revealed hallmark features such as fat stranding around the pancreatic tail and gallbladder wall thickening, confirming the diagnosis of acute pancreatitis and cholecystitis. Post-cholecystectomy, histopathological examination of the gallbladder displayed IgG4-positive staining in multiple vessels, accompanied by perivascular inflammation and fibrinoid necrosis infiltrated by lymphocytes and neutrophils, confirming the diagnosis of IgG4-RD. Subsequent evaluation prompted by systemic manifestations revealed an ANA titer of 1:5120 and a dsDNA titer of 1:80, leading to the diagnosis of SLE. The patient later developed mononeuropathy, which improved upon initiation of immunosuppressive therapy. This case underscores the intricate interplay between IgG4-RD and SLE, an association documented to a limited extent in literature, thereby emphasizing the imperative of considering alternative autoimmune diseases with manifestations akin to IgG4-RD.

Pulmonary Immunocompromise in Chronic and High-dose Steroid Therapy

Glucocorticoid (GC) use is often the mainstay of treatment in many pulmonary, autoimmune, allergic, and oncologic diseases, along with organ transplantation. Short-term and long-term GC use is estimated to be around 1% to 2% worldwide. It has been associated with significant infectious complications such as streptococcus and influenza, mycobacterial infections, and opportunistic infections, specifically Pneumocystis pneumonia, invasive fungal infections, and strongyloidiasis. It is important to use minimal effective dose for the shortest duration to minimize complications. This review summarizes the prevalence of steroid prescriptions, mechanisms, manifestations, and mitigation strategies of pulmonary immunocompromise in patients on chronic and high-dose steroid therapies.

Acute hypophysitis with pachymeningitis

Often the workup to find the causes of common symptoms can lead to unexpected findings, thereby emphasising the need to keep a broad suspicion and continued search for emerging evidence. In this report, we describe the case of an elderly woman in her late 60s without any comorbidities, who presented with new-onset neck stiffness, progressive headache and continuous fever with no other clue that could lead us to a telltale diagnosis, and in whom the diagnostic staircase ultimately led to the diagnosis of IgG4 hypophysitis and pachymeningitis. Only a prompt clinical suspicion and appropriately timed workup can help in revealing such intricate and uncommon diagnosis among the maze of more common differentials having similar manifestations. Especially in such uncommon scenarios, common aetiologies such as tuberculosis should always be kept in the horizon.

Recurrent chylothorax in a patient with serositis as the only manifestation of IgG4-related disease: the diagnostic challenge and consideration

IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory disorder characterised by IgG4-positive plasma cell infiltration into different tissues and organs. Among the heterogeneous clinical features of IgG4-RD, serositis, including pleural and pericardial effusions, is a rare and poorly understood presentation. We described a woman in her late 70s who developed recurrent chylothorax and failed to respond to corticosteroids, immunosuppressives and intrapleural octreotide injection while being treated for newly diagnosed IgG4-RD with serositis as the only manifestation. Her chylothorax was thought to be due to fibroinflammatory damage of the lymphatic duct system from her IgG4-RD, as other differential diagnoses have been largely excluded. We demonstrate the difficulty in establishing the diagnosis of IgG4-RD when only serositis is present, the importance of meticulous workup ruling out other causes and clinical judgement in identifying disease complications versus evaluating alternative diagnoses.

IgG4 Related Disease Presenting With Eosinophilic Pleural Effusion

A 56-year-old man presented with right-sided pleuritic chest pain and intermittent cough for 4 months, with a background history of well-controlled asthma and allergic rhinitis. Chest radiographs revealed right-sided pleural effusion, the fluid chemistry showed an exudate effusion with negative cytology and abundant eosinophils. Thoracoscopic pleural biopsy showed moderate lymphoplasmacytic chronic inflammation. Immunohistochemistry showed IgG4 staining up to 90 plasma cells/hpf (> 10% diagnostic), and the IgG4: IgG ratio was 40% (> 40% diagnostic), confirming the diagnosis of IgG4-related disease (IgG4-RD). Elevated serum IgG4 level (300 mg/dL; normal range: 3-201 mg/dL), further supported the diagnosis. While eosinophilic pleural effusion (EPE) accounts for 5%-16% of all exudative pleural effusions, IgG4-related pleural disease is an extremely rare cause of EPE.

Study on the correlation between serum IgG4/IgG levels and the development of Graves' ophthalmopathy

Graves' ophthalmopathy (GO) with elevated IgG4 levels has different characteristics from patients with GO who do not have elevated IgG4 levels, but the study findings are contradictory. The goal of this study was first to investigate the relationship between IgG4/IgG and IgG4 levels and the occurrence of GO and then to investigate the clinical and laboratory characteristics of patients with GO who had elevated IgG4 levels. This study control group consisted of 57 Graves' disease(GD)patients with no complicated ocular disease and a median followup of 54.41 months, while the experimental group included 171 GO patients. The clinical and laboratory characteristics of the GD and GO groups were compared. Using an IgG4/IgG cut-off value of 8%, the GO patients were divided into two groups: high IgG4/IgG and low IgG4/IgG, and the differences in clinical and laboratory characteristics between these two groups, as well as between the GO patients before and after 3 months of treatment, were analyzed. The study results show that serum IgG4/IgG levels were independently correlated with the occurrence of GO, but not significantly correlated with GO activity. Patients with high IgG4/IgG levels of GO exhibit distinct characteristics, which may be associated with an unstable balance of lymphocyte subsets.

Immune Profile Differences between IgG4-Related Diseases and Primary Sjögren's Syndrome

Purpose

Immunoglobulin G4-related disease (IgG4-RD) share clinical features with primary Sjögren's syndrome (pSS). This study aimed to identify altered serological parameters and potential biomarkers of IgG4-RD and pSS.

Methods

Forty IgG4-RD patients, 40 pSS patients, and 40 healthy controls (HC) were enrolled in this study. Routine serological parameters and clinical manifestations were assessed. IgG subclasses (IgGSc) were detected using a Siemens BN P, and lymphocyte subsets were analyzed using flow cytometry. Cytokines assays were performed using cytometric bead array.

Results

Compared to pSS, IgG4-RD patients had higher IgG4 (p <0.001) and lower IgG1 (p =0.014). The natural killer (NK) cells (p = 0.004), CD4+ T cells (p = 0.028), and TBNK cells (p = 0.040) were increased in IgG4-RD compared to pSS. IgG4 used to differentiate IgG4-RD from pSS produced an area under the curve (AUC) of up to 0.952. In addition, we compared serum parameters, immune cells, and cytokines of IgG4-RDwith mouth dryness or eye dryness with those of pSS with the same symptoms, and similar serological changes were observed. IgG4-RD patients with mouth dryness had higher IgG4 (p <0.001) and Th cells (p = 0.016) but lower IgG1 (p = 0.009) compared to pSS with dry mouth. IgG4-RD patients with eye dryness had higher levels of IgG4 (p <0.001), Treg cells (p = 0.037), and NK cells (p = 0.017) than pSS patients with eye dryness. Moreover, IgG4-RD patients with mouth and eye dryness had higher levels of B (p = 0.006), Th (p = 0.026), Th2 (p = 0.007), and Treg cells (p = 0.028) than IgG4-RD patients without mouth and eye dryness.

Conclusion

Immune system disorder is an outstanding feature of IgG4-RD, and its feature differ from pSS. Assessment of immune status is important in the diagnosis and differential diagnosis of IgG4-RD.

Are there atypical sites of IgG4 related disease in head and neck region? Personal experience and literature review

PURPOSE

Immunoglobulin G4-related disease (IgG4-RD) is a complex systemic fibroinflammatory condition with different clinical manifestations affecting multiple organ systems. Despite its rarity, the disease presents diagnostic and therapeutic challenges due to its mimicry of malignancies and other immune-mediated disorders. The 2019 American College of Rheumatology/European League Against Rheumatism Classification Criteria for IgG4-Related Disease is the current state of art to confirm the diagnosis of IgG4-RD even in the absence of histological analysis. However, this classification excludes atypical sites, focusing on the more typical ones, even in case of histological confirmation. In the ENT field, several localizations of this disease have been described.

METHODS

We report two clinical cases at the Otolaryngology Unit of IRCCS San Martino Hospital, Genoa affected by IgG4-RD arising in atypical sides of the head and neck region. Additionally, we perform a clinical review of the current literature.

DISCUSSION

The review provides an extensive overview of IgG4-RD, encompassing epidemiology, clinical manifestations, diagnostic approaches, and therapeutic strategies. We discuss the evolution of diagnostic criteria, emphasizing the necessity of interdisciplinary collaboration among clinicians, radiologists, and pathologists for accurate diagnosis. Diagnostic imaging plays a crucial role, with characteristic radiological patterns aiding in the identification of affected organs. However, definitive diagnosis often requires histopathological confirmation, highlighting the importance of biopsy in challenging cases. We also focus on the treatment of IgG4-RD which poses significant challenges, with glucocorticoids remaining the cornerstone of therapy. Emerging steroid-sparing agents such as rituximab and Dupilumab, show promising results in refractory or recurrent disease.

CONCLUSIONS

IgG4-RD is a multisystemic fibroinflammatory disease that can potentially affect any part of the body. The 2019 ACR/EULAR 3-stage classification criteria for IgG4-RD considers only a few head and neck sites. Therefore, it is of paramount importance that neurosurgeons, head and neck surgeons, and oral and maxillofacial pathologists are familiar with the clinicopathological manifestations of IgG4-RD in these sites to avoid misdiagnosis and inappropriate treatment, which can lead to a decrease in patients' quality of life. To our knowledge, there are no risk factors or genetic predispositions. Further studies are needed to elucidate the pathophysiology of IgG4-RD with the aim of providing a targeted therapy that could spare steroid-related effects and reduce relapses.

IgG4-related retroperitoneal fibrosis presenting as a peripancreatic mass: a case series

Introduction

IgG4-related disease (IgG4-RD) is a chronic, immune-mediated disorder characterized by widespread inflammation and fibrosis, leading to potential organ dysfunction if untreated. Often underdiagnosed due to subtle and varied symptoms, the disease can affect multiple organ systems. This case series highlights two patients who were diagnosed as cases of IgG4-related retroperitoneal fibrosis.

Methods

A total of two patients were included in this prospective case series who presented to the gastroenterology department of a tertiary care hospital with the same signs and symptoms and were diagnosed with IgG4-related retroperitoneal fibrosis (IgG4-RPF).

Case summary

Two patients were included in our case series, aged 25 and 26 years. The chief complaints included dull, radiating epigastric pain, other symptoms include diffuse abdominal pain, intensified, accompanied by nausea, vomiting, and episodic diarrhea, and a history of B-cell lymphoproliferative disorder. Endoscopic ultrasound (EUS)-)-guided biopsies were performed, showing findings consistent with (IgG4-RPF). Both patients were started on a regimen of prednisolone, pantoprazole, and vitamin D, which they tolerated well without adverse effects. They were advised to follow up with a CT scan after one month.

Conclusion

IgG4-related disease (IgG4-RD) is a rare, chronic condition often presenting as retroperitoneal fibrosis (RPF) and affecting multiple organs. Serum IgG4 levels can be normal in certain cases, histopathological and radiological investigations are necessary for the correct diagnosis. Early initiation of immunosuppressive drugs are necessary for the disease control.

A case of massive hemoptysis caused by immunoglobulin G4-related respiratory disease in adults: case report and review of literature

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated chronic fibro-inflammatory condition, that can involve multiple systems. Immunoglobulin G4-related respiratory disease (IgG4-RRD) is relatively rare, with non-specific clinical symptoms. Hemoptysis is a rare clinical symptom of IgG4-RRD, and cases of massive hemoptysis in adults have not been reported. We present here a rare case of massive hemoptysis caused by IgG4-RRD in adults and review relevant literature. An 84-year-old female presented with recurrent cough and blood-streaked sputum, progressing to massive hemoptysis. Her chest CT showed patchy lesions in the lungs, initially misdiagnosed as a tumor. Ultimately, a biopsy confirmed the diagnosis of IgG4-RRD. The patient was treated with prednisone combined with leflunomide, which controlled her condition and maintained remission. However, after 13 months without hemoptysis, she experienced intermittent hemoptysis followed by a massive episode. Increasing the prednisone dose and continuing leflunomide treatment controlled the condition once again, with no recurrence in the subsequent year of follow-up. In patients with IgG4-RRD, particularly those with hemoptysis, it is essential to remain vigilant for massive hemoptysis. Similarly, in patients with lung patch lesions and no evidence of a tumor on biopsy, IgG4-RRD should not be overlooked. Early diagnosis and timely treatment can improve the patient's clinical prognosis.

Immunoglobulin G4-related disease of the testis masquerading as a testicular mass: a clinical dilemma

Immunoglobulin G4 (IgG4)-related disease is a rare immune-mediated fibro-inflammatory disorder with many clinical manifestations. Most commonly affected sites include the pancreas, salivary glands, kidneys, lachrymal glands, biliary tree, aorta and retroperitoneum; testicular involvement is a rare entity. This report describes a man in his 20s who presented with a persistent painless mass in his left testis. After a thorough examination he underwent orchiectomy to rule out any malignancy of the testis. Histopathology and immunohistochemistry were suggestive of IgG4-related disease. Systemic evaluation showed normal IgG4 levels with no other site of involvement. This is a unique presentation of this rare diagnosis and remains a diagnostic challenge which is difficult to distinguish from the more common testicular malignancy. We conducted a review of the current literature regarding IgG4-related disease to complement the case discussion and provide a comprehensive review regarding this diagnostic dilemma.

IgG4-related disease for the hematologist

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated disease with many important manifestations in hematopoietic and lymphoid tissue. IgG4 is the least naturally abundant IgG subclass, and the hallmark feature of IgG4-RD is markedly increased IgG4-positive plasma cells (with an IgG4 to IgG ratio >40%) in affected tissue, along with elevated polyclonal serum IgG and IgG4 in most patients. Histological diagnosis is essential, and other key features include storiform fibrosis, lymphoplasmacytic infiltrate, tissue eosinophilia, and obliterative phlebitis. The disease can present with predominantly proliferative features, such as swollen lacrimal and salivary glands, orbital pseudotumor, autoimmune pancreatitis, polyclonal hypergammaglobulinemia (PHGG), eosinophilia, and tubulointerstitial nephritis of the kidneys, or predominantly fibrotic disease, including mediastinal and retroperitoneal fibrosis, sclerosing mesenteritis, and hypertrophic pachymeningitis. This review focuses on 4 key hematological manifestations: PHGG, IgG4-positive plasma cell enriched lymphadenopathy (LAD), eosinophilia, and retroperitoneal fibrosis (RPF). These features are found in 70%, 60%, 40%, and 25% of IgG4-RD patients, respectively, but can also represent key hematological "mimickers" of IgG4-RD, including Castleman disease (PHGG, LAD), eosinophilic vasculitis (eosinophilia, PHGG, LAD), hypereosinophilic syndromes (eosinophilia, LAD, PHGG), and histiocyte disorders (PHGG, LAD, RPF). An organized approach to these 4 manifestations, and how to distinguish IgG4-RD from its mimickers, is explained. Proliferative manifestations typically respond very well to treatment corticosteroids, rituximab, and other immunosuppressives, whereas chronic fibrotic disease may not be reversible with current treatment modalities.

Systemic diseases affecting the GI tract: A review of clinical and histopathologic manifestations

A variety of systemic diseases may affect the gastrointestinal (GI) tract. Since the GI tract responds to injury in limited ways, identifying these processes may be challenging, especially on small endoscopic biopsies. This article reviews the clinicopathologic features of commonly encountered systemic diseases affecting the tubular GI tract: sarcoidosis, graft vs. host disease, mast cell disorders, systemic sclerosis, and IgG-4 related disease. In addition, we offer guidance in differentiating them from their mimics.

IgG4-related disease mimicking a liver abscess

IgG4-related disease (IGRD) is a complex medical condition affecting multiple organs, including the liver. The condition is characterized by excessive production of IgG4 antibodies, leading to chronic inflammation and tissue damage. We present a case of a 37-year-old man with a history of chronic pancreatitis was diagnosed with a liver mass. Initial treatment included piperacillin and tazobactam, but the patient's condition worsened. An ultrasound-guided biopsy revealed increased IgG4 positive cells, leading to the diagnosis of an inflammatory pseudotumor associated with IGRD. The patient was treated with prednisone taper therapy, and the liver mass resolved after six months of corticoid treatment.

Clinical profile of IgG4-related disease in Japan based on the rare disease data registry

We started a registry for cases of immunoglobulin (Ig)G4-related disease (IgG4-RD) in December 2019 to clarify the clinical profile of IgG4-RD. In this study, clinical information from 854 cases registered by February 16, 2024 was analyzed from multiple perspectives. Diagnosis of IgG4-RD was made in 808 cases, comprising 638 definite, 38 probable, and 132 possible. The mean ± SD age at time of enrollment of the 808 cases was 67.9 ± 11.3 years, with 68.8% being male. The pancreas was the most frequently affected organ (49.8%), followed by the submandibular glands (46.2%) and lacrimal glands (30.6%). This study reconfirmed the pancreas and head-and-neck region as major affected areas in IgG4-RD. Clinically, submandibular adenitis and autoimmune pancreatitis often occur together in the same patient, but no association between the two organs was observed in our analysis. Regarding diagnosis, the comprehensive diagnostic criteria were most commonly used (63.6%). Storiform fibrosis and phlebitis obliterans were detected at different frequencies in different organs. In summary, this registry study identified clinical, imaging, hematologic, and pathologic findings in 808 Japanese patients with IgG4-RD. The frequency of affected organs and their characteristic pathological findings will be particularly useful for future practice.

Multiorgan involvement and circulating IgG1 predict hypocomplementaemia in IgG4-related disease

OBJECTIVES

Hypocomplementaemia is common in patients with IgG4-related disease (IgG4-RD). We aimed to determine the IgG4-RD features associated with hypocomplementaemia and investigate mechanisms of complement activation in this disease.

METHODS

We performed a single-centre cross-sectional study of 279 patients who fulfilled the IgG4-RD classification criteria, using unadjusted and multivariable-adjusted logistic regression to identify factors associated with hypocomplementaemia.

RESULTS

Hypocomplementaemia was observed in 90 (32%) patients. In the unadjusted model, the number of organs involved (OR 1.42, 95% CI 1.23 to 1.63) and involvement of the lymph nodes (OR 3.87, 95% CI 2.19 to 6.86), lungs (OR 3.81, 95% CI 2.10 to 6.89), pancreas (OR 1.66, 95% CI 1.001 to 2.76), liver (OR 2.73, 95% CI 1.17 to 6.36) and kidneys (OR 2.48, 95% CI 1.47 to 4.18) were each associated with hypocomplementaemia. After adjusting for age, sex and number of organs involved, only lymph node (OR 2.59, 95% CI 1.36 to 4.91) and lung (OR 2.56, 95% CI 1.35 to 4.89) involvement remained associated with hypocomplementaemia while the association with renal involvement was attenuated (OR 1.6, 95% CI 0.92 to 2.98). Fibrotic disease manifestations (OR 0.43, 95% CI 0.21 to 0.87) and lacrimal gland involvement (OR 0.53, 95% CI 0.28 to 0.999) were inversely associated with hypocomplementaemia in the adjusted analysis. Hypocomplementaemia was associated with higher concentrations of all IgG subclasses and IgE (all p<0.05). After adjusting for serum IgG1 and IgG3, only IgG1 but not IgG4 remained strongly associated with hypocomplementaemia.

CONCLUSIONS

Hypocomplementaemia in IgG4-RD is not unique to patients with renal involvement and may reflect the extent of disease. IgG1 independently correlates with hypocomplementaemia in IgG4-RD, but IgG4 does not. Complement activation is likely involved in IgG4-RD pathophysiology.

The Enigma of Retroperitoneal Fibrosis: Clinical Implications and Diagnostic and Therapeutic Challenges

Retroperitoneal fibrosis (RPF) is a rare disease with a nonspecific presentation. RPF can be classified into Idiopathic, the most common, or secondary due to malignancy and various medications resulting in chronic inflammation and fibrosis in the retroperitoneum. The complications arise due to the compression of structures in the retroperitoneum. The most common presentations are constitutional symptoms, abdominal pain, and renal insufficiency due to ureteral obstruction. Venous thrombosis or claudication on presentation is rare. Diagnosis and treatment remain challenging due to the lack of standard diagnostic or treatment protocols. Our patient presented with symptoms of acute deep vein thrombosis (DVT) with varices on the abdomen and mild bilateral hydronephrosis. A CT scan revealed a retroperitoneal mass, which was confirmed to be RPF by biopsy. Relevant laboratory tests, including IgG4, were negative. High-dose corticosteroid therapy reduced the inflammatory markers and the size of the retroperitoneal mass.

Imaging of the Major Salivary Glands in Rheumatic Disease

Salivary gland involvement is a common feature of rheumatologic disease. The authors review the anatomy of the major salivary glands and the uses of imaging modalities such as ultrasound, MRI, computed tomography, sialography, and scintigraphy in evaluating the major salivary glands in rheumatologic disease.

IgG4-related Breast Disease: Review of the Literature

IgG4-related disease (IgG4-RD) is a rare illness with inflammatory and fibrotic changes in affected organs such as pancreas, thyroid, salivary or lacrimal glands, and retroperitoneal space; rarely other organs may be involved. IgG4-related breast disease (IgG4-BD) is very rare and generally presents as a lump or mastitis. IgG4-BD as a presenting feature of IgG4-RD is extremely rare. Hence, this paper reviews the known (n=48) IgG-BD cases reported in the literature to date. The majority of cases were diagnosed on routine mammography or during assessment for other clinically significant features. The absence of a lump border, and especially the absence of calcifications on ultrasonography, mammography, or computed tomography, is typical for IgG4-BD. Characteristic IgG4-BD pathological findings were dense lymphoplasmacytic infiltration with stromal fibrosis, and more than 10% IgG4+ plasma cells/high-power field (HPF); the mean percentage of IgG4+/IgG+ plasma cells was 54.2%, and only one-third of the patients had all "classical" signs of IgG4-BD including storiform fibrosis and obliterative phlebitis. Most of the cases had a benign course and responded to surgical excision with or without steroid therapy.

Omics in IgG4-related disease

ABSTRACT

Research on IgG4-related disease (IgG4-RD), an autoimmune condition recognized to be a unique disease entity only two decades ago, has processed from describing patients' symptoms and signs to summarizing its critical pathological features, and further to investigating key pathogenic mechanisms. Challenges in gaining a better understanding of the disease, however, stem from its relative rarity-potentially attributed to underrecognition - and the absence of ideal experimental animal models. Recently, with the development of various high-throughput techniques, "omics" studies at different levels (particularly the single-cell omics) have shown promise in providing detailed molecular features of IgG4-RD. While, the application of omics approaches in IgG4-RD is still at an early stage. In this paper, we review the current progress of omics research in IgG4-RD and discuss the value of machine learning methods in analyzing the data with high dimensionality.

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

BACKGROUND

In 2018, diagnostic criteria were introduced for IgG4-related periaortitis/periarteritis and retroperitoneal fibrosis (PA/RPF). This study assessed the existing criteria and formulated an improved version.

METHODS AND RESULTS

Between August 2022 and January 2023, we retrospectively analyzed 110 Japanese patients diagnosed with IgG4-related disease (IgG4-RD) involving cardiovascular and/or retroperitoneal manifestations, along with 73 non-IgG4-RD patients ("mimickers") identified by experts. Patients were stratified into derivation (n=88) and validation (n=95) groups. Classification as IgG4-RD or non-IgG4-RD was based on the 2018 diagnostic criteria and various revised versions. Sensitivity and specificity were calculated using experts' diagnosis as the gold standard for the diagnosis of true IgG4-RD and mimickers. In the derivation group, the 2018 criteria showed 58.5% sensitivity and 100% specificity. The revised version, incorporating "radiologic findings of pericarditis", "eosinophilic infiltration or lymphoid follicles", and "probable diagnosis of extra-PA/-RPF lesions", improved sensitivity to 69.8% while maintaining 100% specificity. In the validation group, the original and revised criteria had sensitivities of 68.4% and 77.2%, respectively, and specificities of 97.4% and 94.7%, respectively.

CONCLUSIONS

Proposed 2023 revised IgG4-related cardiovascular/retroperitoneal disease criteria show significantly enhanced sensitivity while preserving high specificity, achieved through the inclusion of new items in radiologic, pathological, and extra-cardiovascular/retroperitoneal organ categories.

IgG4-related disease: Effectiveness evaluation through Umehara-Okazaki 2011 and ACR/EULAR 2019 diagnostic criteria

BACKGROUND

IgG4-related disease (IgG4-RD) is a rare, systemic immune-mediated fibro-inflammatory condition with an unclear etiology and pathophysiology, potentially affecting multiple organs. It presents with common clinical, radiological, and serological characteristics. This study aims to compare the latest two IgG4-RD classification and diagnostic criteria: Umehara-Okazaki 2011 and ACR/EULAR 2019.

MATERIAL AND METHODS

In a retrospective cross-sectional study conducted across two centers from January 2010 to July 2023, we included patients suspected of having IgG4-RD from various hospital departments. Patients finally diagnosed with other pathologies were excluded. The remaining suspected IgG4-RD cases were evaluated using both Umehara-Okazaki 2011 and ACR/EULAR 2019 criteria.

RESULTS

Out of 34 patients with a clinical diagnosis of IgG4-RD, the Umehara-Okazaki 2011 classified 20 patients: 5 as definitive, 7 as probable, and 8 as possible cases. Applying the ACR/EULAR 2019 criteria to the same cohort resulted in the diagnosis of 9 patients. Notably, retroperitoneal fibrosis and aortitis were the most prevalent form of presentation, accounting for 25% and 22.2% of cases classified under the 2011 and 2019 criteria, respectively.

DISCUSSION

The more recent and stringent ACR/EULAR 2019 criteria focus on histopathology, various forms of presentation, and analytical data, allow for a more accurate classification of patients.

Factors related to elevated serum immunoglobulin G4 (IgG4) levels in a Japanese general population

BACKGROUND

Elevated serum immunoglobulin G4 (IgG4) concentrations are one of the characteristic findings in IgG4-related disease (IgG4-RD). This study investigated the frequency of elevated serum IgG4 levels and associated factors in a general Japanese population.

METHODS

Serum IgG4 concentrations were measured in 1,201 residents of Ishikawa prefecture who underwent general medical examinations. Factors associated with elevated serum IgG4 concentrations were assessed by logistic regression analysis. Participants with elevated serum IgG4 were subjected to secondary examinations.

RESULTS

The mean serum IgG4 concentration was 44 mg/dL, with 42 (3.5%) participants having elevated serum IgG4 levels. Age- and sex-adjusted logistic regression analyses showed that male sex, older age, and lower intake of lipids and polyunsaturated fatty acids and higher intake of carbohydrates in daily diet were associated with elevated serum IgG4 concentration. Subgroup analyses in men showed that older age, lower estimated glomerular filtration rates based on serum cystatin C (eGFR-cysC) levels, and higher hemoglobin A1c (HbA1c) levels were associated with elevated serum IgG4 concentration. Analyses in women showed that lower intake of lipids and fatty acids and higher intake of carbohydrates were significantly associated with elevated serum IgG4 concentration. One of the 15 participants who underwent secondary examinations was diagnosed with possible IgG4-related retroperitoneal fibrosis.

CONCLUSIONS

Elevated serum IgG4 levels in a Japanese general population were significantly associated with older age, male gender, and dietary intake of nutrients, with some of these factors identical to the epidemiological features of IgG4-RD.

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.

Neurologic Manifestations of Rheumatologic Disorders

OBJECTIVE

This article provides an overview of the neurologic manifestations of sarcoidosis and select rheumatologic disorders. An approach to the assessment and differential diagnosis of characteristic clinical presentations, including meningitis and vasculitis, is also reviewed. A review of treatment options is included as well as discussion of distinct areas of overlap, including rheumatologic disease in the setting of neuromyelitis spectrum disorder and demyelinating disease in the setting of tumor necrosis factor-α inhibitors.

LATEST DEVELOPMENTS

An increased understanding of the immune mechanisms involved in sarcoidosis and rheumatologic diseases has resulted in a greater diversity of therapeutic options for their treatment. Evidence directing the treatment of the central nervous system (CNS) manifestations of these same diseases is lacking, with a paucity of controlled trials.

ESSENTIAL POINTS

It is important to have a basic knowledge of the common CNS manifestations of rheumatologic diseases and sarcoidosis so that they can be recognized when encountered. In the context of many systemic inflammatory diseases, including systemic lupus erythematosus, IgG4-related disease, and sarcoidosis, CNS disease may be a presenting feature or occur without systemic manifestations of the disease, making familiarity with these diseases even more important.

Proliferative features of IgG4-related disease

IgG4-related disease is an immune-mediated disease that can lead to substantial morbidity and organ damage. Capable of affecting nearly any organ system or anatomic site, and showing considerable overlap in clinical presentation with various other diseases, IgG4-related disease often poses a diagnostic challenge for clinicians. Furthermore, there are no diagnostic biomarkers with high specificity for IgG4-related disease, and histopathological examination is nuanced and requires clinical correlation for accurate diagnosis. Therefore, it is crucial for clinicians to recognise the clinical phenotypes of IgG4-related disease. The disease is generally considered to have predominantly fibrotic and proliferative (or inflammatory) manifestations, with distinct clinical, serological and histopathological findings associated with each manifestation. However, the fibrotic and proliferative manifestations of this disease frequently occur together, thereby blurring this dichotomous distinction. In this Series paper, we provide a detailed overview of the clinical manifestations typical of the proliferative features of IgG4-related disease, with an emphasis on the diagnostic evaluation and differential diagnosis of each proliferative disease manifestation. In addition, we summarise the immune mechanisms underlying IgG4-related disease, suggest a framework for how to approach management and monitoring after the diagnosis is established, and highlight current unmet needs for patient care surrounding this disease.

Navigating the Diagnostic Maze: A Case Report of Immunoglobulin G4-Related Disease

Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory condition characterized by significant infiltration of immunoglobulin G4 (IgG4)-positive plasma cells within affected tissues, with or without elevated serum IgG4 levels. The prevalence of IgG4-RD remains largely undetermined due to diagnostic challenges, as the condition is frequently unrecognized or misdiagnosed. This report describes a case of a 63-year-old man who was ultimately diagnosed with this rare condition after an extensive two-year period of elusive symptoms. Initially presenting with intermittent body pains and fluctuating fever, his condition progressively evolved to include severe right orbital swelling with marked tenderness and ecchymosis, recurrent non-tender nodules on his arm, and diminished vision. A detailed review of his medical history prompted the consideration of IgG4-RD, leading to the measurement of serum human IgG4 levels, which were found to be significantly elevated at 1504 mg/L (normal range: 39.2-864 mg/L). Following his diagnosis, treatment with glucocorticoids (0.6 mg/kg for one month) was initiated, resulting in a positive clinical response. This case emphasizes the critical importance of considering less common conditions in the differential diagnosis of patients presenting with complex, multi-system symptoms.

Immunoglobulin G4-related thoracic disease: clinical and radiological findings of a Turkish cohort

BACKGROUND AND AIM

Thoracic involvement of Immunoglobulin G4-related disease (IgG4-RD) is relatively rare and may be disregarded at the time of initial diagnosis due to its asymptomatic nature. This study aimed to ascertain the prevalence and patterns of thoracic involvement in a retrospective cohort of Turkish patients with IgG4-RD.

METHODS

A total of 90 patients (47 males and 43 females, with a mean age of 57.7±15.5 years) diagnosed with IgG4-RD were reviewed retrospectively. All computed tomography (CT) scans were re-evaluated by two thoracic radiologists and IgG4-related thoracic disease was assessed on four compartments: The mediastinum, pulmonary parenchyma, airways, and pleura. IgG4-related thoracic disease was categorized as: definite, highly probable, probable or possible.

RESULTS

There were 64 patients who had undergone at least one thorax CT examination, and 18 (28%) were diagnosed with IgG4-related thoracic disease. The rate of IgG4-related thoracic disease increased by 20% and reached a ratio of 48.4% (n=31) after a thorough reevaluation of registry data specifically to thoracic findings. The mediastinum was the most frequently involved compartment, affecting 16 (51.6%) patients, followed by pulmonary parenchyma in 14 (45.2%) patients, and airways and pleura in 10 (32.3%) patients each. Other organ involvements were more prevalent and IgG4 levels were higher in patients with thoracic involvement. Eosinophils were significantly elevated in patients with thoracic involvement (p=0.023).

CONCLUSIONS

IgG4-related thoracic disease is heterogeneous and likely to be more prevalent than currently recognized. The mediastinum is the most frequently involved compartment. It is important to assess IgG4-related thoracic disease at the time of initial diagnosis. Elevated levels of serum IgG4 and eosinophils, as well as a greater number of organ involvements may serve as indicators of thoracic involvement.

Pathogenic roles of follicular helper T cells in IgG4-related disease and implications for potential therapy

IgG4-related disease (IgG4-RD) is a recently described autoimmune disorder characterized by elevated serum IgG4 levels and tissue infiltration of IgG4+ plasma cells in multiple organ systems. Recent advancements have significantly enhanced our understanding of the pathological mechanism underlying this immune-mediated disease. T cell immunity plays a crucial role in the pathogenesis of IgG4-RD, and follicular helper T cells (Tfh) are particularly important in germinal center (GC) formation, plasmablast differentiation, and IgG4 class-switching. Apart from serum IgG4 concentrations, the expansion of circulating Tfh2 cells and plasmablasts may also serve as novel biomarkers for disease diagnosis and activity monitoring in IgG4-RD. Further exploration into the pathogenic roles of Tfh in IgG4-RD could potentially lead to identifying new therapeutic targets that offer more effective alternatives for treating this condition. In this review, we will focus on the current knowledge regarding the pathogenic roles Tfh cells play in IgG4-RD and outline potential therapeutic targets for future clinical intervention.

Transudative pleural effusion in pleuritis associated with immunoglobulin G4-related disease diagnosed by thoracoscopy under local anaesthesia

Immunoglobulin G4 (IgG4)-related disease is a chronic inflammatory condition often characterized by exudative pleural effusions. However, transudative pleural effusions, like in the presented case of an 80-year-old man with multiple comorbidities, are less common but possible. Despite initial treatment with diuretics, the effusion persisted, prompting further investigation. Medical thoracoscopy revealed lymphatic follicle hyperplasia and an abundance of IgG4-positive plasmacytoid cells, confirming IgG4-related pleuritis. This case underscores the importance of considering inflammatory etiologies, such as IgG4-related disease, when faced with unresponsive transudative pleural effusions. Thoracoscopy serves as a valuable diagnostic tool in such scenarios, allowing for precise diagnosis and appropriate management.

Coronary artery wall contrast enhancement imaging impact on disease activity assessment in IgG4-RD: a direct marker of coronary involvement

BACKGROUND

Coronary artery wall contrast enhancement (CE) has been applied to non-invasive visualization of changes to the coronary artery wall in systemic lupus erythematosus (SLE). This study investigated the feasibility of quantifying CE to detect coronary involvement in IgG4-related disease (IgG4-RD), as well as the influence on disease activity assessment.

METHODS

A total of 93 subjects (31 IgG4-RD; 29 SLE; 33 controls) were recruited in the study. Coronary artery wall imaging was performed in a 3.0 T MRI scanner. Serological markers and IgG4-RD Responder Index (IgG4-RD-RI) scores were collected for correlation analysis.

RESULTS

Coronary wall CE was observed in 29 (94 %) IgG4-RD patients and 22 (76 %) SLE patients. Contrast-to-noise ratio (CNR) and total CE area were significantly higher in patient groups compared to controls (CNR: 6.1 ± 2.7 [IgG4-RD] v. 4.2 ± 2.3 [SLE] v. 1.9 ± 1.5 [control], P < 0.001; Total CE area: 3.0 [3.0-6.6] v. 1.7 [1.5-2.6] v. 0.3 [0.3-0.9], P < 0.001). In the IgG4-RD group, CNR and total CE area were correlated with the RI (CNR: r = 0.55, P = 0.002; total CE area: r = 0.39, P = 0.031). RI´ scored considering coronary involvement by CE, differed significantly from RI scored without consideration of CE (RI v. RI´: 15 ± 6 v. 16 ± 6, P < 0.001).

CONCLUSIONS

Visualization and quantification of CMR coronary CE by CNR and total CE area could be utilized to detect subclinical and clinical coronary wall involvement, which is prevalent in IgG4-RD. The potential inclusion of small and medium-sized vessel involvements in the assessment of disease activity in IgG4-RD is worthy of further investigation.

IgG4-related disease-rare but you should not forget it

Immunoglobulin G4-related disease is a systemic immune-mediated disease with insidious evolution characterized by fibroinflammatory lesions over virtually any organ system. Despite the remarkable progression of knowledge, its etiology remains undefined. Due to its relapse-remitting pattern, it could accumulate irreversible damage, increasing comorbidities and mortality. This paper emphasizes key concepts for diagnosing and treating patients with this condition.

Ultrasound and Sialogram Correlates to Parotid Immunoglobulin G4-Related Disease

Immunoglobulin G4 (IgG4)-related disease is an immune-mediated disorder that commonly manifests in the salivary glands. As a recently described disorder, the description and classification of IgG4-related disease is an ongoing process. Diagnosis of IgG4-related disease requires integration of clinical history, histopathology, and radiographic findings, including ultrasonography and sialography. In this case report, we correlate parotid ultrasonographic and sialographic findings in a patient with proven IgG4-related disorder confirmed from analysis of previous submandibular gland resections. We aim to highlight the utility of multimodality imaging in the diagnosis of IgG4-related disease.

Current and future advances in practice: IgG4-related disease

IgG4-related disease (IgG4-RD) is an increasingly recognized cause of fibroinflammatory lesions in patients of diverse racial and ethnic backgrounds and is associated with an increased risk of death. The aetiology of IgG4-RD is incompletely understood, but evidence to date suggests that B and T cells are important players in pathogenesis, both of which are key targets of ongoing drug development programmes. The diagnosis of IgG4-RD requires clinicopathological correlation because there is no highly specific or sensitive test. Glucocorticoids are highly effective, but their use is limited by toxicity, highlighting the need for studies investigating the efficacy of glucocorticoid-sparing agents. B cell-targeted therapies, particularly rituximab, have demonstrated benefit, but no randomized clinical trials have evaluated their efficacy. If untreated or under-treated, IgG4-RD can cause irreversible organ damage, hence close monitoring and consideration for long-term immunosuppression is warranted in certain cases.

A Diagnostic Paradox: Identifying IgG4-Related Disease in a Patient Previously Diagnosed with Sjogren's Syndrome

We present the case of a 77-year-old male with a history of rectal adenocarcinoma and Sjogren's disease who was admitted for severely elevated liver function tests. Cross-sectional imaging demonstrated a dilated bile duct, and eventual biopsy of the area showed fibrosis and lymphocytic infiltrate consistent with IgG4-related disease. The patient was treated with rituximab and a prednisone taper. This case discusses the clinical, laboratory, and imaging hallmarks of this rare disease and illustrates the practical challenges of distinguishing it from other rheumatologic conditions.

High serum IgA levels in patients with IgG4-related disease are associated with mild inflammation, sufficient disease-specific features, and favourable responses to treatments

OBJECTIVES

Although elevated serum immunoglobulin A (IgA) levels are thought to exclude a diagnosis of IgG4-related disease (IgG4-RD), IgG4-RD has been definitively diagnosed in some patients despite elevated serum IgA levels. This study aimed to clarify the prevalence of elevated IgA levels in patients with IgG4-RD and to compare the clinical features of IgG4-RD patients with and without elevated IgA levels.

METHODS

The clinical features of 169 IgG4-RD patients were retrospectively compared among those with and without elevated serum IgA levels.

RESULTS

Of the 169 patients with IgG4-RD, 17 (10.1%) had elevated serum IgA levels. Those with elevated serum IgA levels showed higher serum C-reactive protein levels and lower prevalence of relapse than those without. Other clinical features did not differ significantly, including inclusion scores of the American College of Rheumatology/European League Against Rheumatism classification criteria. Cox regression analysis showed that elevated serum IgA levels were associated with a lower incidence of relapse. Moreover, patients with elevated serum IgA levels showed prompt improvement in response to glucocorticoids in the IgG4-RD responder index.

CONCLUSIONS

Some patients diagnosed with IgG4-RD have high serum IgA levels. These patients may form a subgroup, characterized by good response to glucocorticoids, less frequent relapse, mildly elevated serum C-reactive protein levels, and possible complications of autoimmune diseases.

Mimickers of immunoglobulin G4-related hepatobiliary disease on biopsy

With the growing recognition of IgG4-related hepatobiliary disease, establishing a definitive diagnosis relies mainly on a combination of clinical findings, serological markers, and imaging modalities. However, the role of histopathological evaluation remains indispensable, particularly in cases necessitating differential diagnosis or malignancy exclusion. While diagnosing IgG4-related hepatobiliary disease through surgical resection specimens is often straightforward, pathologists encounter substantial challenges when evaluating biopsies. The increasing rarity of surgical interventions exacerbates this due to improved disease recognition and suspicion. Numerous confounding factors, including the absence of the characteristic histologic features, limited tissue sample size, biopsy artifacts, and the limited value of IgG4 counts, further complicate the diagnostic process. Additionally, many other disorders exhibit clinical and histological features that overlap with IgG4-related disease, intensifying the complexity of interpreting biopsy specimens. This article explores the clinical and histomorphologic features of IgG4-related hepatobiliary disease and its potential mimickers. It offers valuable insights for pathologists and clinicians when confronted with biopsy specimens from hepatobiliary organs.

IgG4-related lymphadenopathy

IgG4-related lymphadenopathy is a nodal manifestation of IgG4-related disease (IgG4RD) which is characterized by increased polytypic IgG4+ plasma cells and IgG4+/IgG+ plasma cell ratio in lymph nodes and morphologically manifested as various patterns of reactive lymphadenopathy: Castleman disease-like, follicular hyperplasia, interfollicular expansion, progressive transformation of germinal centers and inflammatory pseudotumor-like. It typically presents with solitary or multiple, mild to moderate lymph node enlargement in otherwise asymptomatic patients. The serum IgG4 level is frequently elevated but C-reactive protein often remains normal. In patients not having a history of IgG4RD or manifestation of extranodal IgG4RD, a diagnosis of IgG4-lymphadenopathy should only be made with great caution given the non-specific morphologic features that can overlap with ANCA-associated vasculitis, interleukin-6 syndromes, Rosai-Dorfman disease, inflammatory myofibroblastic tumor, syphilis, lymphoma, and plasma cell neoplasia. Elevated IgG4 parameters, appropriate morphologies, and clinical correlation are essential to make the diagnosis of IgG4-lymphadenopathy more specific and clinically meaningful.

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.

Two Surgical Cases of Colorectal Cancer in Patients With Immunoglobulin G4-Related Disease

Immunoglobulin G4-related disease (IgG4RD) is a relatively new disease concept that is most common in Asia. It is a systemic chronic lymphoproliferative disease that is diagnosed by mass formation or thickened lesion, a high serum IgG4 level (≥135 mg/dL), and confirmation of lymphocytes and plasma cells by histopathological examination. The precise mechanism of this disease remains elusive; however, distinguishing IgG4RD from malignancy proves challenging due to its manifestation of swollen lymph nodes and retroperitoneal thickening and fibrosis. Malignancy is also 3.5 times more likely in cases with IgG4RD. In this study, we report two cases of colorectal cancer in patients with IgG4RD who underwent surgery. In both cases, excising the tumor from the retroperitoneal posed a challenge, and swollen lymph nodes were observed without evidence of cancer metastasis. We believe that these are very informative cases, and we report the cases with a literature review of IgG4RD.

Autoimmune pancreatitis: Cornerstones and future perspectives

Autoimmune pancreatitis (AIP) is an autoimmune subtype of chronic pancreatitis resulting from the aberrant immune response against the pancreas, leading to inflammation and fibrosis. Although AIP is rare, its incidence is increasing and is often misdiagnosed as other pancreatic diseases. AIP is commonly classified into two types. Type 1 AIP (AIP-1) is typically associated with elevated serum immunoglobulin G4 (IgG4) levels and systemic manifestations, while type 2 AIP is typically a more localized form of the disease, and may coexist with other autoimmune disorders, especially inflammatory bowel diseases. Additionally, there is emerging recognition of a third type (type 3 AIP), which refers to immunotherapy-triggered AIP, although this classification is still gaining acceptance in medical literature. The clinical manifestations of AIP mainly include painless jaundice and weight loss. Elevated serum IgG4 levels are particularly characteristic of AIP-1. Diagnosis relies on a combination of clinical, laboratory, radiological, and histological findings, given the similarity of AIP symptoms to other pancreatic disorders. The mainstay of treatment for AIP is steroid therapy, which is effective in most cases. Severe cases might require additional imm-unosuppressive agents. This review aims to summarize the current knowledge of AIP, encompassing its epidemiology, etiology, clinical presentation, diagnosis, and treatment options. We also address the challenges and controversies in diagnosing and treating AIP, such as distinguishing it from pancreatic cancer and managing long-term treatment, highlighting the need for increased awareness and knowledge of this complex disease.

Immunoglobulin G4-Related Disease Complicating Ruptured Isolated Iliac Artery Aneurysm: A Complex Management Dilemma

BACKGROUND Managing IgG4-related disease (IgG4-RD) in the context of vascular complications, such as aneurysms, poses significant challenges, particularly when considering surgical intervention options. The risk of rupture and infection in patients on long-term glucocorticoid therapy complicates treatment decisions. CASE REPORT A 63-year-old woman with a history of IgG4-RD presented with a ruptured right iliac artery aneurysm. She was on long-term oral glucocorticoid therapy. Initial emergency endovascular stent graft implantation was followed by embolization for suspected arterial bleeding and subsequent Salmonella bacteremia. Repeated hospitalizations involved stent graft removal and surgical repair due to persistent infection. Over 2 years, the patient required multiple pelvic drainages and long-term antibiotic and prednisolone therapy, yet her quality of life remained compromised. CONCLUSIONS Our case highlights the unique challenges and considerations in the treatment of IgG4-related aneurysms. Patients with IgG4-RD who are on long-term oral glucocorticoids have an inherent risk of aneurysm rupture. We believe regular follow-ups to monitor the progression of the aorta and iliac arteries into aneurysms are essential. For patients who have developed aneurysms, it is advisable to reduce the dosage of glucocorticoids or even consider surgical treatment as soon as possible. As for the choice of surgical method, there is no consensus yet. While endovascular treatment is less invasive and quicker, it can increase the risk of rupture and bleeding. Open surgery might be a better option. More data are needed to make a definitive judgment.

Mass spectrometry in IgG4-related disease diagnosis

We compared liquid chromatography tandem mass spectrometry (LC-MS/MS) against Binding Site immunonephelometry (BSIN) with regards to these methods' abilities to diagnose IgG4-related disease (IgG4-RD). IgG subclasses were gathered from laboratory from December 2011 to December 2020. The IgG4-RD positive and negative patients were diagnosed according to the ACR/EULAR classification criteria by extensive chart review. Both methods' results were compared in terms of test characteristics. For BSIN, there were 43 IgG4-RD positive cases and 174 disease negative cases, while for LC-MS/MS, there were 102 IgG4-RD positive cases and 562 disease negative cases. The majority of IgG4-RD patients by BSIN and LC-MS/MS had an elevated IgG4 level, 81% and 86%, respectively. For BSIN, the ROC curve, cut-off value of 1.25 g/L, had a sensitivity of 81% and a specificity of 84%. For LC-MS/MS, the ROC curve, cut-off value of 1.25 g/L, had a sensitivity of 86% and a specificity of 84%. The responder index score to IgG4 level r-correlation value for BSIN and LC-MS/MS was 0.5 and 0.6, respectively. In our center, LC-MS/MS and BSIN are equivalent test methods in IgG4-RD diagnosis. IgG4 level does correlate with disease activity by the responder index. LC-MS/MS is a valid and equally reliable alternative to BSIN in the diagnosis of IgG4-related disease.

Clinical patterns and risk factors for multiorgan involvement in IgG4-Related disease patients

Background

IgG4-related disease with multiorgan involvement predicts higher disease activity, thus, it is necessary to identify whether IgG4-related disease involves multiple organs at the early stage. To further clarify the clinical characteristics and risk factors for IgG4-related disease with multiorgan involvement, we conducted an observational study.

Methods

We retrospectively analysed the clinical data of 160 patients who were primarily diagnosed with IgG4-related disease at the First Affiliated Hospital of Zhengzhou University from January 2015 to January 2021. According to the number of involved organs, patients were divided into two groups: multiorgan involvement and nonmultiorgan involvement. Patients were divided into a multiorgan group and a nonmultiorgan group according to multiple organ involvement.

Results

There were 82 cases identified with multiorgan involvement and 78 cases diagnosed with no multiorgan involvement in this series. Most cases were elderly and male (p > 0.05). The most frequently affected organs in IgG4-RD were the lymph nodes (50.6 %), pancreas (38.7 %) and salivary glands (35.6 %). Multivariate analysis showed that eosinophilia, IgG4>2*ULN, lymph node involvement, salivary gland involvement and lung involvement were independent risk factors for multiorgan involvement (p < 0.05).

Conclusions

The main issues in clinical practice are how to accurately diagnose the disease and screen the more vulnerable organs.

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.