The risk of malignancy in patients with IgG4-related disease: a systematic review and meta-analysis

The immunological pathogenesis of IgG4-related disease categorized by clinical characteristics

IgG4-related disease (IgG4-RD) is an immune disorder characterized by organ enlargement and fibrosis leading to functional impairment. Key immune cell subsets contributing to the pathogenesis of IgG4-RD include T follicular helper 2 cells (Tfh2), Tfh1, CX3CR1 + cytotoxic T cells (CX3CR1 + CTLs), Tregs and IgG4 + B cells. Tfh2 and Tregs are commonly involved in inducing IgG4 class-switching in this disease. Importantly, IgG4-RD can be classified into four clinical phenotypes based on the distribution of affected organs, with each phenotype showing different dominant immune cell subsets involved in its pathogenesis. Specifically, the clinical phenotype of retroperitoneal fibrosis/aortitis is characterized by CX3CR1 + CTLs as the dominant key immune cell subset, while Mikulicz disease with systemic involvement is dominated by Tfh2. In addition to classification based on organ distribution, IgG4-RD can also be categorized into phenotypes associated with malignancy or allergy. The malignancy phenotype is characterized by an increase in CXCR5 + CD2-double negative T cells compared to the allergy phenotype, along with a decrease in naive CD8 + T cells. Moreover, several autoantigens have been identified, and the presence of autoimmune phenotype has been revealed. Due to the pathogenicity of IgG1-type autoantibodies, Tfh1 may be important inducing IgG1 class-switching by IFNγ in autoimmune phenotype. In IgG4-RD with hypocomplementemia, activation of the complement pathway is thought to be induced by IgG1 or IgG2 antibodies, suggesting the involvement of Tfh1 in the disease pathogenesis. Therefore, elucidating the immunological features specific to each clinical characteristic is believed to lead to a deeper understanding of the pathogenesis of IgG4-RD and the discovery of novel therapeutic targets. This review provides an overview of the immunological mechanisms common to IgG4-RD as well as those specific to each clinical characteristic.

Histopathological Markers of Immunoglobulin G4-related Disease: Analyzing Diagnostic Patterns and Immunohistochemical Findings

Introduction: Immunoglobulin G4 (IgG4) related disease is a localized or multisystem chronic inflammatory disease with characteristic pathological features. Several consensus criteria are available to aid in the diagnosis and its management. These criteria are highly specific, owing to their dependency on major histopathological criteria and laboratory investigations to diagnose IgG4-related diseases (IgG4-RD). We evaluated the lesions diagnosed as IgG4-RDs with histopathological scoring criteria based on histopathology, immunohistochemistry, and serology in the screening of IgG4-RDs. Materials and methods: The lesions diagnosed as IgG4-RD during the study period were evaluated using the histopathological scoring criteria which include storiform fibrosis, obliterative phlebitis, plasmacytic infiltrates, and lymphoid follicles. Immunohistochemistry with IgG4 was performed on all these lesions. Results: There were twelve patients with IgG4-RD involving the retroperitoneum, pancreas, lymph node, and nasal sinuses. Lesions involving the retroperitoneum showed all the characteristic histopathological findings of IgG4-RD. Storiform fibrosis and obliterative vasculitis were seen in 67% and 58% of the lesions respectively. Two patients (17%) lacked both storiform fibrosis and obliterative phlebitis. Additionally, lymphoid follicles were present in 58%, perineural infiltration in 33%, and tissue eosinophilia in 58% of individuals. Two patients with eosinophilic angiocentric fibrosis and a single patient with IgG4-RD associated with retroperitoneal mucinous cystadenoma were identified. Conclusion: IgG4-RD is a group of rare diseases that needs a multidisciplinary team approach for diagnosis. In our study, we report a rare association of IgG4-RD and retroperitoneal mucinous cystadenoma as well as rare lesions of IgG4-related eosinophilic angiocentric fibrosis. Clinicopathological and radiological correlation is crucial in the accurate diagnosis of IgG4-RD and to avoid overdiagnosis.

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.

Pharmacological Management of IgG4-Related Disease: From Traditional to Mechanism-Based Targeted Therapies

IgG4-related disease (IgG4-RD) is an immune-mediated disorder characterized by organ enlargement and dysfunction. The formation of tertiary lymphoid tissues (TLTs) in affected organs is crucial for understanding IgG4-RD, as T follicular helper (Tfh) 2 cells within TLTs drive IgG4+B cell differentiation, contributing to mass formation. Key cytokines IL-4 and IL-10, produced by Tfh2 cells, are essential for this process. Additionally, cytotoxic T cells and M2 macrophages significantly contribute to inflammation and fibrosis in the lesions. These insights into IgG4-RD have led to the development of innovative targeted therapies. While glucocorticoids are effective in many cases, they often cause disease flares during tapering and rarely result in long-term, treatment-free remissions. Long-term glucocorticoid use poses significant challenges owing to potential side effects, particularly in older patients who may already have complications such as diabetes and atherosclerotic diseases. In contrast, targeted therapies offer a promising alternative, potentially providing more effective disease control with fewer side effects. Current research is exploring several exciting approaches, including B-cell depletion, targeted immunomodulation of B cells, Bruton's tyrosine kinase inhibition, disruption of co-stimulation pathways, targeting the SLAMF7 cytokine or its receptor blockade (BAFF, IL-4, or IL-6), and JAK-STAT signaling pathway inhibition. These emerging strategies hold the promise of improving patient outcomes and advancing the management of IgG4-RD.

Epigenetic age acceleration and methylation differences in IgG4-related cholangitis and primary sclerosing cholangitis

BACKGROUND

IgG4-related cholangitis (IgG4-SC) and primary sclerosing cholangitis (PSC) are chronic fibro-inflammatory hepatobiliary conditions, with genetic, environmental, and immunologic risk factors, in which epigenetic alterations may provide insights into pathophysiology and novel biomarkers. This study is the first to assess methylation signatures in IgG4-SC.

RESULTS

Whole blood DNA methylation profiling and genotyping was performed in 264 individuals; 47 with IgG4-SC, 65 with PSC, 64 with ulcerative colitis (UC), and 88 healthy controls. We identified 19 significant methylation differences between IgG4-SC and controls and 38 between PSC and controls. IgG4-SC and PSC shared 8 probes. Inflammatory genes (including CEP97, IFNAR1, TXK, HERC6, C5orf36, PYY, and MTRNR2L1) were predominantly involved in dysregulated methylation. Epigenetic age acceleration was observed in patients with IgG4-SC, but not in those with PSC or UC. meQTL analyses to identify genetic determinants of methylation revealed a strong human leucocyte antigen (HLA) signal in both PSC and IgG4-SC (HLA-DQB2, HLA-DPA1, HLA-F and HLA-DRA).

CONCLUSIONS

We identify novel epigenetic alterations in IgG4-SC and PSC, with biological age acceleration in IgG4-SC, providing insights into disease pathogenesis, and highlight the role of genetic variation especially within the HLA region in shaping the methylome.

Human T follicular helper cells and their impact on IgE and IgG4 production across allergy, malignancy, and IgG4-related disease

Human T follicular helper (Tfh) cells play a crucial role in orchestrating B cell differentiation, maturation, and immunoglobulin class switching. Recent studies have underscored the presence of Bcl-6 + Tfh cells not only in secondary lymphoid organs but also within tertiary lymphoid structures at inflammatory sites, emphasizing their pivotal role in disease pathogenesis. Furthermore, Tfh cells have been found to transit between lesion sites, lymph nodes, and peripheral blood, as revealed by T cell receptor repertoire analysis. Among Tfh subsets, Tfh2 cells have emerged as central orchestrators in driving the production of IgE and IgG4 from B cells. Their critical role in diseases such as allergy, malignancy, and IgG4-related disease highlights their profound impact on balancing inflammation and immune tolerance. Our current review provides the molecular characteristics of human Tfh cells, the differentiation pathways of Tfh subsets, mechanisms by which Tfh subsets induce IgE and IgG4 production, and their clinical implications in allergy, malignancy, and IgG4-related disease.

Diffuse large B-cell lymphoma with rapid kidney enlargement after induction of hemodialysis in a patient with IgG4-related disease

A 76-year-old Japanese man was incidentally diagnosed with a pancreatic head tumor on computed tomography after surgery for colon cancer. He underwent pancreatoduodenectomy and was diagnosed with IgG4-related autoimmune pancreatitis. Concurrent chronic kidney disease gradually progressed and chronic hemodialysis was introduced 2 years later. Six months after the introduction of hemodialysis, follow-up abdominal computed tomography revealed marked enlargement of bilateral kidneys compared with previous images. Blood tests revealed persistent high IgG and IgG4 levels, and IgG4-related kidney disease was suspected. Thus, percutaneous kidney biopsy was performed. No evidence of IgG4-related kidney disease was detected, and a diagnosis of diffuse large B-cell lymphoma was made. Six courses of combination chemotherapy consisting of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone was effective, and the patient achieved and maintained complete remission for five years. This case highlights the need to consider the possible development of malignant lymphoma within several years after IgG4-related disease, especially in cases of autoimmune pancreatitis.

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.

Immunoglobulin G4 in primary Sjögren's syndrome and IgG4-related disease - connections and dissimilarities

Primary Sjögren's syndrome (pSS) is an autoimmune disease, with B cell hyperactivation and autoantibody production as its immunological hallmarks. Although the distinction between immunoglobulin G4-related disease (IgG4-RD) and pSS, based on the presence or absence of certain autoantibodies, seems easy to make, possibility of elevated serum IgG4 concentration and often similar organ involvement may lead to a misdiagnosis. The increased serum concentration of IgG4 in IgG4-RD is not clearly linked to the pathogenesis of IgG-RD and it has been suggested that it may constitute just an epiphenomenon. The aim of this article is to discuss the presence of IgG4 in pSS and IgG4-RD and its potential significance for these two diseases.

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.

The clinical outcomes and healthcare resource utilization in IgG4-related disease: a claims-based analysis of commercially insured adults in the United States

OBJECTIVES

IgG4-related disease (IgG4-RD) can affect nearly any organ and is often treated with glucocorticoids, which contribute to organ damage and toxicity. Comorbidities and healthcare utilization in IgG4-RD are poorly understood.

METHODS

We conducted a cohort study using claims data from a US managed care organization. Incident IgG4-RD cases were identified using a validated algorithm; general population comparators were matched by age, sex, race/ethnicity and index date. The frequency of 21 expert-defined clinical outcomes associated with IgG4-RD or its treatment and healthcare-associated visits and costs were assessed 12 months before and 36 months after the index date (date of earliest IgG4-RD-related claim).

RESULTS

There were 524 cases and 5240 comparators. Most cases received glucocorticoids prior to (64.0%) and after (85.1%) the index date. Nearly all outcomes, many being common glucocorticoid toxicities, occurred more frequently in cases vs comparators. During follow-up, the largest differences between cases and comparators were seen for gastroesophageal reflux disease (prevalence difference: +31.2%, P < 0.001), infections (+17.3%, P < 0.001), hypertension (+15.5%, P < 0.01) and diabetes mellitus (+15.0%, P < 0.001). The difference in malignancy increased during follow-up from +8.8% to +12.5% (P < 0.001). Some 17.4% of cases used pancreatic enzyme replacement therapy during follow-up. Over follow-up, cases were more often hospitalized (57.3% vs 17.2%, P < 0.01) and/or had an emergency room visit (72.0% vs 36.7%, P < 0.01); all costs were greater in cases than comparators.

CONCLUSIONS

Patients with IgG4-RD are disproportionately affected by adverse outcomes, some of which may be preventable or modifiable with vigilant clinician monitoring. Glucocorticoid-sparing treatments may improve these outcomes.

IgG4-related disease and B-cell malignancy due to an IKZF1 gain-of-function variant

BACKGROUND

Monoallelic loss-of-function IKZF1 (IKAROS) variants cause B-cell deficiency or combined immunodeficiency, whereas monoallelic gain-of-function (GOF) IKZF1 variants have recently been reported to cause hypergammaglobulinemia, abnormal plasma cell differentiation, autoimmune and allergic manifestations, and infections.

OBJECTIVE

We studied 7 relatives with autoimmune/inflammatory and lymphoproliferative manifestations to identify the immunologic disturbances and the genetic cause of their disease.

METHODS

We analyzed biopsy results and performed whole-exome sequencing and immunologic studies.

RESULTS

Disease onset occurred at a mean age of 25.2 years (range, 10-64, years). Six patients suffered from autoimmune/inflammatory diseases, 4 had confirmed IG4-related disease (IgG4-RD), and 5 developed B-cell malignancies: lymphoma in 4 and multiple myeloma in the remaining patient. Patients without immunosuppression were not particularly prone to infectious diseases. Three patients suffered from life-threatening coronavirus disease 2019 pneumonia, of whom 1 had autoantibodies neutralizing IFN-α. The recently described IKZF1 GOF p.R183H variant was found in the 5 affected relatives tested and in a 6-year-old asymptomatic girl. Immunologic analysis revealed hypergammaglobulinemia and high frequencies of certain lymphocyte subsets (exhausted B cells, effector memory CD4 T cells, effector memory CD4 T cells that have regained surface expression of CD45RA and CD28-CD57+ CD4+ and CD8+ T cells, TH2, and Tfh2 cells) attesting to immune dysregulation. Partial clinical responses to rituximab and corticosteroids were observed, and treatment with lenalidomide, which promotes IKAROS degradation, was initiated in 3 patients.

CONCLUSIONS

Heterozygosity for GOF IKZF1 variants underlies autoimmunity/inflammatory diseases, IgG4-RD, and B-cell malignancies, the onset of which may occur in adulthood. Clinical and immunologic data are similar to those for patients with unexplained IgG4-RD. Patients may therefore benefit from treatments inhibiting pathways displaying IKAROS-mediated overactivity.

Advances in understanding and management of IgG4-related ophthalmic disease

Immunoglobulin G4-related ophthalmic disease (IgG4-ROD) is an emerging, immune-mediated fibroinflammatory orbital disease, characterized by tumefactive lesions with noticeable IgG4+ plasma cell infiltration and distinctive pathohistological features. This disease is often associated with elevated serum IgG4 concentrations. IgG4-ROD may affect any ophthalmic tissues, particularly the lacrimal gland, extraocular muscles, and trigeminal nerves. Although the exact pathogenic role of IgG4 antibodies remains unclear, B-cell depleting agents have been reported to be an effective treatment. The diverse clinical manifestations of IgG4-ROD complicate diagnosis, and without prompt treatment, visual-threatening complications such as optic neuropathy may arise. Recent advances in understanding and managing IgG4-ROD have revolutionized the diagnosis and treatment of this emerging disease. This review article aims to provide a comprehensive overview of the latest advancements in the field of IgG4-ROD.

An Evasive Liver Mass in a Human Immunodeficiency Virus (HIV)-Positive Patient

IgG4-related disease (IgG4-RD) is an autoimmune syndrome that is characterized by elevated levels of serum IgG4 and infiltration of various tissue types by IgG4 immunoreactive plasma cells. The IgG4-RD can result in systemic disease and the formation of inflammatory mass lesions, frequently addressed as pseudotumors. While IgG4-RD can manifest in various organs, liver involvement is rare, and because it is an immune-mediated inflammatory process, it is uncommon in patients who are immunocompromised. Furthermore, despite IgG4-RD responding well to immunosuppressive treatment, cases of spontaneous remission are exceedingly rare in the literature. In this report, we present the unique case of a self-resolving IgG4-RD lesion of the liver in a HIV positive patient.

Elevated polyclonal IgG4 mimicking a monoclonal gammopathy in IgG4-related disease-a case-based review

IgG4-related diseases (IgG-RDs) are a group of fibroinflammatory diseases that affect a variety of tissues, resulting in tumour-like effects and/or organ dysfunction. Monoclonal gammopathies (MGPs) are a group of disorders characterized by clonal proliferation of plasma cells or lymphoid cells resulting in the secretion of a monoclonal immunoglobulin. Cases of MGPs in IgG4-RDs coexisting with plasma cell dyscrasias and lymphoid neoplasms have been reported over the past few years. Therefore, the results of examinations of M protein in IgG4-RD patients should be interpreted with caution. Herein, we report the case of a 58-year-old male with a history of type 2 diabetes who presented with submandibular masses, anosmia, swollen lymph nodes, proteinuria, and renal impairment. Laboratory tests revealed hyperglobulinemia and elevated levels of IgG4 (124 g/L) and serum-free light chains (sFLCs). Serum protein electrophoresis (SPEP) revealed an M spike of 5.6 g/dL, and immunofixation electrophoresis (IPE) revealed biclonal IgG-κ and IgG-λ. The patient underwent bone marrow, lymph node, and kidney biopsy, which ruled out plasma cell disorders and lymphoma. He was finally diagnosed with an IgG4-RD comorbid with diabetic nephropathy. The findings in this case highlight that significant activation of B cells in IgG4-RD patients, especially those with multiorgan involvement can lead to significant hyperglobulinemia and high sFLC and IgG4 levels, which are more pronounced in the setting of renal impairment. Relatively high concentrations of polyclonal IgG4 can give rise to a focal band bridging the β and γ fractions, which may mimic the appearance of a monoclonal band on SPEP and monoclonal gammaglobulinemia in IFE. The patient experienced considerable improvement in his symptoms after rituximab combined with glucocorticoid therapy, and a monoclonal immunoglobulin was not detected.

IgG4-related disease: Case report and 6-year follow-up of an elusive diagnosis mimicking malignancy

Key Clinical Message

IgG4-related disease is a rare and emerging pathology, characterized by the appearance of pseudotumors. Due to the ability to mimic other pathologies, it is essential to consider it as a differential diagnosis in multisystemic processes. The diagnosis is challenging, requiring a multidisciplinary approach, to minimize the associated morbidity and mortality.

Abstract

IgG4-related disease (IgG4-RD) is a rare, emerging, systemic and chronic pathology, characterized by the appearance of pseudotumors resulting from tissue infiltration by IgG4-positive plasma cells that promote eosinophilic inflammation of the tissue with subsequent fibrosis. We present the case of a male, 45-year-old patient, with marked weight loss and skin pallor detected by his family doctor during a child health consultation of his daughter. When questioned, the patient referred complaints of postprandial discomfort in the left hypochondrium with a feeling of fullness, weight loss, chronic fatigue and hyperhidrosis that had lasted for a month. On physical examination, he was pale, and had pain at palpation of the left hypochondrium. Laboratory data showed increased inflammation markers, abdominal ultrasound and CT demonstrated numerous enlarged lymph nodes in the upper quadrants, raising concern for a malignant lymphoproliferative process. Serological, imaging, clinical and laparoscopic excisional biopsy revealed features of IgG4-related disease and excluded malignant lymphoproliferative disease. The immediate response to treatment with oral prednisolone 30 mg/day also contributed for diagnosis confirmation. Due to refractory disease after gradual prednisolone reduction, second-line therapy with rituximab was initiated. Over the 6 years of follow-up, the patient presented multiple exacerbations characterized by the emergence of systemic symptoms, being maintained under close clinical and imaging follow-up by reumathology, infectious diseases, and family medicine specialists.

Myelodysplastic syndrome with IgG4‑related disease: A case report

At present, to the best of our knowledge, there are only a few case reports of IgG4-related disease (IgG4-RD) involving myelodysplastic syndrome (MDS), yet the incidence of MDS and IgG4-RD is increasing in middle-aged and elderly people. The present study presents a case of MDS combined with IgG4-RD admitted to Zhejiang Provincial Hospital of Chinese Medicine in September 2022. The (66-year-old; male) patient was admitted to the hospital due to hematopenia with an elevated IgG4 index. The diagnosis of MDS combined with IgG4-RD was confirmed after various exams, including pathological examination. The condition of the patient improved after 3 weeks of hormone therapy, with a significant increase in complete blood count compared with the pre-treatment period. MDS is a malignant hematological disorder with a high risk of conversion to leukemia, and IgG4-RD is a systemic immune-mediated disease with a poor prognosis often associated with malignancy. The present study presents and reviews the literature to better understand the coexistence of these two diseases.

Increased Age-Adjusted Cancer Mortality After the Third mRNA-Lipid Nanoparticle Vaccine Dose During the COVID-19 Pandemic in Japan

During the COVID-19 pandemic, excess deaths including cancer have become a concern in Japan, which has a rapidly aging population. Thus, this study aimed to evaluate how age-adjusted mortality rates (AMRs) for different types of cancer in Japan changed during the COVID-19 pandemic (2020-2022). Official statistics from Japan were used to compare observed annual and monthly AMRs with predicted rates based on pre-pandemic (2010-2019) figures using logistic regression analysis. No significant excess mortality was observed during the first year of the pandemic (2020). However, some excess cancer mortalities were observed in 2021 after mass vaccination with the first and second vaccine doses, and significant excess mortalities were observed for all cancers and some specific types of cancer (including ovarian cancer, leukemia, prostate cancer, lip/oral/pharyngeal cancer, pancreatic cancer, and breast cancer) after mass vaccination with the third dose in 2022. AMRs for the four cancers with the most deaths (lung, colorectal, stomach, and liver) showed a decreasing trend until the first year of the pandemic in 2020, but the rate of decrease slowed in 2021 and 2022. This study discusses possible explanations for these increases in age-adjusted cancer mortality rates.

Cardiac Tamponade as an Initial Manifestation of Diffuse Large B-cell Lymphoma One Year after IgG4-related Disease in Remission

A 65-year-old man with multiple lymphadenopathies was diagnosed with IgG4-related disease (IgG4-RD) based on findings of a cervical lymph node biopsy and an elevated serum IgG4 level. Treatment was initiated after the onset of autoimmune pancreatitis, and he achieved remission. He developed diffuse large B-cell lymphoma one year later. Pericardial involvement of lymphoma resulted in cardiac tamponade, and he died before histopathological confirmation of lymphoma was made due to a lethal arrhythmia caused by massive involvement of lymphoma into the myocardium. Because patients with IgG4-RD might have an increased risk of malignant diseases, including lymphoma, histopathological examinations should be considered at any time during the course of IgG4-RD.

Utility of 18F-FDG PET/CT for differential diagnosis between IgG4-related lymphadenopathy and angioimmunoblastic T-cell lymphoma

AIM

To explore the utility of the 2-[18F]-fluoro-2-deoxy-d-glucose (18F-FDG) positron-emission tomography (PET)/computed tomography (CT) in the differential diagnosis of IgG4-related lymphadenopathy (IgG4-RLAD) and angioimmunoblastic T-cell lymphoma (AITL).

MATERIALS AND METHODS

Retrospective analysis of 18F-FDG PET/CT imaging findings in clinically diagnosed IgG4-RLAD and AITL cases was undertaken to record the distribution, morphological characteristics, and imaging features of the affected lymph nodes, as well as FDG uptake of the spleen and bone marrow. Standardised uptake values normalised to lean body mass were evaluated for maximum (SULmax), average (SULavg), and peak values (SULpeak). Univariate and multivariate logistic regression was used to screen for statistically significant imaging findings to discriminate IgG4-RLAD from AITL.

RESULTS

Twenty-two cases of IgG4-RLAD (17 men, five women, median age 49.5 years) and 22 cases of AITL (16 men, six women, median age 55 years) were finally included in the analysis. There were no AITL patients with involvement of a single lymph node region. AITL patients had more involvement of the different nodal regions except cervical and pelvic nodal regions. A practical assessment method based on a combination of SULpeak-LN/SULavg-liver, SULpeak-spleen, and the number of involved nodal regions, improved the performance for differential diagnosis between both groups with an overall classification accuracy of 90.9%.

CONCLUSIONS

18F-FDG PET/CT is a useful tool for distinguishing AITL from IgG4-RLAD, and it can also help determine the optimal biopsy site for suspected cases of IgG4-RLAD or AITL, reduce the need for re-biopsy procedures, and enable physicians to develop timely treatment strategies.

IgG4 autoantibodies and autoantigens in the context of IgG4-autoimmune disease and IgG4-related disease

Immunoglobulins are an essential part of the humoral immune response. IgG4 antibodies are the least prevalent subclass and have unique structural and functional properties. In this review, we discuss IgG4 class switch and B cell production. We review the importance of IgG4 antibodies in the context of allergic responses, helminth infections and malignancy. We discuss their anti-inflammatory and tolerogenic effects in allergen-specific immunotherapy, and ability to evade the immune system in parasitic infection and tumour cells. We then focus on the role of IgG4 autoantibodies and autoantigens in IgG4-autoimmune diseases and IgG4-related disease, highlighting important parallels and differences between them. In IgG4-autoimmune diseases, pathogenesis is based on a direct role of IgG4 antibodies binding to self-antigens and disturbing homeostasis. In IgG4-related disease, where affected organs are infiltrated with IgG4-expressing plasma cells, IgG4 antibodies may also directly target a number of self-antigens or be overexpressed as an epiphenomenon of the disease. These antigen-driven processes require critical T and B cell interaction. Lastly, we explore the current gaps in our knowledge and how these may be addressed.

The mRNA-LNP vaccines - the good, the bad and the ugly?

The mRNA-LNP vaccine has received much attention during the COVID-19 pandemic since it served as the basis of the most widely used SARS-CoV-2 vaccines in Western countries. Based on early clinical trial data, these vaccines were deemed safe and effective for all demographics. However, the latest data raise serious concerns about the safety and effectiveness of these vaccines. Here, we review some of the safety and efficacy concerns identified to date. We also discuss the potential mechanism of observed adverse events related to the use of these vaccines and whether they can be mitigated by alterations of this vaccine mechanism approach.

Immunoglobulin G4-related Dacryoadenitis Successfully Treated with Baricitinib

A 48-year-old woman visited our hospital because of bilateral lacrimal gland enlargement. Her serum immunoglobulin G4 (IgG4) level was high, and positron emission tomography-computed tomography showed significant positive findings in the bilateral lacrimal gland. A biopsy revealed a considerable increase in IgG4/CD138, leading to a diagnosis of IgG4-related dacryoadenitis. The disease did not respond to steroid therapy, so treatment was started with baricitinib because of exacerbation of the original atopic dermatitis and dacryoadenitis after the second dose of the coronavirus disease 2019 (COVID-19) vaccine. Baricitinib was effective for resolving both dermatitis and dacryoadenitis, and steroids were able to be discontinued. The IgG4 level also improved.

Coexistence of Colorectal Cancer and Immunoglobulin G4-Related Disease in the Same Lesion: A Rare Case with Molecular Classification

Immunoglobulin G4-related disease (IgG4-RD) is a novel fibroinflammatory disorder characterized by enlargement of the involved organs, elevated IgG4 levels, and abundant infiltration of IgG4-positive plasma cells. Indeed, primary colon cancers arising from IgG4-RD are rare. This case report describes a rare occurrence of simultaneous colorectal cancer and IgG4-RD in the same lesion in a 62-year-old male patient. The patient underwent a right hemicolectomy under the suspicion of primary colon cancer. The mass was grossly well-defined and yellowish tan, and the background colon was fibrotic. Microscopically, the tumor cells showed glandular differentiation characteristic of adenocarcinoma in a background of dense lymphoplasmacytic infiltration with fibrosis and obliterative phlebitis in the pericolic fat tissue. IgG4 immunohistochemical staining showed diffuse positivity in infiltrating plasma cells. The patient was administered adjuvant chemotherapy and prednisolone therapy. The patient's serum IgG4 levels gradually decreased, and a follow-up positron emission tomography-computed tomography scan 1 year after surgery showed no evidence of local or distant recurrence of colorectal cancer. IgG4-RD occurring concurrently with primary colon adenocarcinoma has not been reported. Increased awareness of this rare coexistence can guide clinicians in navigating diagnostic complexities and selecting optimal therapeutic strategies.

Value of High-Frequency Ultrasonography in the Qualitative and Semi-Quantitative Assessment of Immunoglobulin G4-Related Submandibular Sialadenitis

OBJECTIVE

To assess the value of high-frequency ultrasonography in the evaluation of immunoglobulin G4-related submandibular sialadenitis (IgG4-SS).

METHODS

Thirty-four submandibular glands in 17 patients with IgG4-SS were retrospectively enrolled, as well as 34 submandibular glands in 17 healthy control subjects. Qualitative ultrasonic features including submandibular gland size, border, echogenicity, and vascularity were reviewed. Two different scoring systems (0-16 and 0-48, respectively) were used for semi-quantitative analysis of imaging features. Comparison of both qualitative and semi-quantitative ultrasonic analysis were made between patients with IgG4-SS and healthy controls. Spearman correlation was used to explore relationships between variables.

RESULTS

The submandibular glands with IgG4-SS presented with enlarged size, rough border, increased vascularity, and abnormal echogenicity (All P < .05). The most common echogenicity pattern for IgG-SS was diffuse hypoechoic foci pattern (44.1%), followed by superficial hypoechoic pattern (20.6%), tumor-like pattern (14.7%), and diffuse hypoechogenicity pattern (11.8%). Most IgG4-SS glands presented linear hyperechogenicity in parenchyma (91.2%). Based on both scoring system, scores of IgG4-SS were significantly higher than those of the controls (All P < .05). Association analysis of both scoring systems showed positive correlation of scores with vascularity in the gland parenchyma (All P < .05).

CONCLUSION

The ultrasonic features of IgG4-SS comprise enlarged gland, rough border, increased vascularity, and abnormal echogenicity, which correlate with its pathological characteristics. The most common echogenicity pattern for IgG4-SS was diffuse hypoechoic foci pattern. Semi-quantitative analysis systems could be useful in the assessment of IgG4-SS. Ultrasound is a potential, valuable, and non-invasive tool for the diagnosis and evaluation of IgG4-SS.

A case of pancreatic ductal adenocarcinoma concomitant with IgG4-related disease in the pancreas and the stomach

A 75-year-old Japanese woman visited a hospital with a stomachache. The patient was diagnosed with localized mild acute pancreatitis. Blood tests revealed elevated serum IgG4 levels. Contrast-enhanced computed tomography showed a hypovascular mass, 3 cm in size, in the pancreatic body with dilation of the upstream duct. Additionally, it showed another tumorous lesion of 10 mm in size in the anterior wall of the stomach, and endoscopic examination confirmed a submucosal tumor (SMT) sized 10 mm in the anterior wall of the stomach. Endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNAB) of the pancreas revealed an adenocarcinoma concomitant with marked IgG4-positive cell infiltration. Hence, distal pancreatectomy with local gastrectomy was performed, and the final diagnosis was concluded as pancreatic ductal adenocarcinoma (PDAC) complicated by IgG4-related diseases (IgG4-RD) in the pancreas and stomach. IgG4-RD of the digestive tract is exceedingly rare. The correlation between PDAC and autoimmune pancreatitis or malignancy and IgG4-RD is controversial. However, the clinical course and histopathological examination, in this case, provide valuable suggestive findings for further discussion.

A Case of Immunoglobulin G4-Related Disease Presenting as a Parapharyngeal Mass

Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory condition characterized by tissue infiltration with lymphocytes and IgG4-secreting plasma cells. The presentation of IgG4-RD is heterogenous, making it difficult to diagnose. IgG4-RD presenting as a parapharyngeal mass is extremely rare. This report discusses the case of a 69-year-old African American female presenting with intermittent bilateral frontal headaches. Initial imaging revealed an ill-defined parapharyngeal mass encasing the left internal carotid artery and left internal jugular vein. Subsequent biopsy and immunohistochemistry showed a high concentration of IgG4-positive plasma cells with storiform fibrosis, despite normal serum IgG4 levels. The patient opted for conservative management. The localized parapharyngeal mass has remained stable over two years on annual imaging. This case report highlights that IgG4-RD can have varied and nonspecific presentations requiring high clinical suspicion to diagnose. Histopathology and IgG4 staining are vital to confirm the diagnosis of IgG4-RD, particularly in atypical cases not meeting the standard inclusion criteria.

Incidence, prevalence and mortality of IgG4-related disease in the USA: a claims-based analysis of commercially insured adults

BACKGROUND

IgG4-related disease (IgG4-RD) is an immune-mediated condition that can affect nearly any organ or anatomic site. We sought to describe the epidemiology of IgG4-RD in the USA.

METHODS

We used Optum's deidentified Clinformatics Data Mart Database from 1 January 2009 to 31 December 2021 to identify IgG4-RD cases using a validated algorithm. We estimated the incidence rate and prevalence between 2015 and 2019 (when rates stabilised), standardised to the US population by age and sex. We compared mortality rates among patients with IgG4-RD to the non-IgG4-RD population matched in a 1:10 ratio on age, sex, race/ethnicity and encounter date. We used Cox proportional hazards models to estimate HRs and 95% CIs.

RESULTS

We identified 524 IgG4-RD cases. The mean age was 56.5 years with 57.6% female and 66% White. The incidence of IgG4-RD increased during the study period from 0.78 to 1.39 per 100 000 person-years in 2015 and 2019, respectively. The point prevalence on 1 Janury 2019 was 5.3/100 000 persons. During follow-up, there were 39 and 164 deaths among 515 IgG4-RD cases and 5160 comparators, resulting in a mortality rate of 3.42 and 1.46/100 person-years, respectively, and adjusted HR of 2.51 (95% CI 1.76 to 3.56).

CONCLUSIONS

The incidence of IgG4-RD is similar to that of systemic rheumatic diseases such as ANCA-associated vasculitis and systemic sclerosis but may be increasing as familiarity with this diagnosis grows. Clinicians should be aware of this condition, especially given the excess risk of death. Identification of effective therapies is an important research agenda.

Immunoglobulin G4-Related Disease, Lymphadenopathy, and Lymphoma

Lymphadenopathy occurring in patients with immunoglobulin G4 (IgG4)-related disease, termed IgG4-related lymphadenopathy, shows morphologic heterogeneity and overlap with other nonspecific causes of lymphadenopathy including infections, immune-related disorders, and neoplasms. This review describes the characteristic histopathologic features and diagnostic approach to IgG4-related disease and IgG4-related lymphadenopathy, with comparison to nonspecific causes of increased IgG4-positive plasma cells in lymph nodes, and with emphasis on distinction from IgG4-expressing lymphoproliferative disorders.

Gastric linitis plastica with autoimmune pancreatitis diagnosed by an endoscopic ultrasonography-guided fine-needle biopsy: A case report

BACKGROUND

Gastric linitis plastica (GLP) is a subset of gastric cancer with a poor prognosis. It is difficult to obtain a definitive diagnosis by endoscopic mucosal biopsies, and the usefulness of an endoscopic ultrasonography-guided fine-needle biopsy (EUS-FNB) for GLP has been recently reported. Meanwhile, autoimmune diseases are occasionally known to coexist with malignant tumors as paraneoplastic syndrome. We herein report the usefulness of an EUS-FNB for detecting GLP and the possibility of paraneoplastic syndrome coexisting with GLP.

CASE SUMMARY

An 81-year-old man was admitted to our hospital for a 1-mo history of epigastric pain that increased after eating. His laboratory data revealed high levels of serum carbohydrate antigen 19-9 and immunoglobulin-G4. Endoscopic examinations showed giant gastric folds and reddish mucosa; however, no epithelial changes were observed. The gastric lumen was not distensible by air inflation, suggesting GLP. Computed tomography showed the thickened gastric wall, the diffuse enlargement of the pancreas, and the peripancreatic rim, which suggested autoimmune pancreatitis (AIP) coexisting with GLP. Because the pathological findings of the endoscopic biopsy showed no malignancy, he underwent an EUS-FNB and was diagnosed with GLP. He received chemotherapy for unresectable gastric cancer due to peritoneal metastasis, after which both the gastric wall thickening and diffuse enlargement of the pancreas were improved.

CONCLUSION

An EUS-FNB for GLP with a negative endoscopic biopsy is useful, and AIP may develop as a paraneoplastic syndrome.

Clinical and Radiological Features of Diffuse Lacrimal Gland Enlargement: Comparisons among Various Etiologies in 91 Biopsy-Confirmed Patients

Objective

To compare the clinical and radiological features of various etiologies of chronic diffuse lacrimal gland enlargement.

Materials and Methods

We retrospectively reviewed 91 consecutive patients who underwent surgical biopsy for chronic diffuse lacrimal gland enlargement and were diagnosed with non-specific dacryoadenitis (DA) (n = 42), immunoglobulin G4-related dacryoadenitis (IgG4-RD) (n = 33), and lymphoma (n = 16). Data on patient demographics, clinical presentation, and CT imaging findings (n = 73) and MRI (n = 43) were collected. The following radiologic features of lacrimal gland enlargement were evaluated: size, unilaterality, wedge sign, angle with the orbital wall, heterogeneity, signal intensity, degree of enhancement, patterns of dynamic contrast-enhanced, and apparent diffusion coefficient value. Radiological features outside the lacrimal glands, such as extra-lacrimal orbital involvement and extra-orbital head and neck involvement, were also evaluated. The clinical and radiological findings were compared among the three diseases.

Results

Compared to the DA and IgG4-RD groups, the lymphoma group was significantly older (mean 59.9 vs. 46.0 and 49.4 years, respectively; p = 0.001) and had a higher frequency of unilateral involvement (62.5% vs. 31.0% and 15.2%, respectively; p = 0.004). Compared to the IgG4-RD and lymphoma groups, the DA group had significantly smaller lacrimal glands (2.3 vs. 2.8 and 3.3 cm, respectively; p < 0.001) and a lower proportion of cases with a wedge sign (54.8% vs. 84.8% and 87.5%, respectively; p = 0.005). The IgG4-RD group showed more frequent involvement of the extra-orbital head and neck structures, including the infraorbital nerve (36.4%), paranasal sinus (72.7%), and salivary gland (58.6%) compared to the DA and lymphoma groups (4.8%–28.6%) (all p < 0.005).

Conclusion

Patient age, unilaterality, lacrimal gland size, wedge sign, and extra-orbital head and neck involvement differed significantly different between lymphoma, DA, and IgG4-RD. Our results will be useful for the differential diagnosis and proper management of chronic lacrimal gland enlargement.

[Immunoglobulin-G4-related disease]

After years of confusion about apparently distinct clinical disease symptoms, the term IgG4-related disease (IgG4-RD) has been coined in 2001, uniting these fibroinflammatory clinical entities with a tendency for tumorous enlargement and tissue fibrosis. Over the past two decades, experimental and clinical studies could make astounding progress in the understanding of this elusive disease. By now, we have a reasonable idea of the pathophysiological mechanisms, which opens up new avenues for therapeutic approaches. It seems like a dense lymphoplasmacytic cell infiltrate, consisting of B‑cells, IgG4⁺ plasma cells, follicular T‑helper cells, CD4⁺ cytotoxic T‑cells and M2 macrophages induces a smoldering inflammatory reaction with a fibrogenic cytokine milieu. This stimulates fibroblasts to secrete extracellular matrix components, leading to the histopathologically characteristic storiform fibrosis and obliterative phlebitis. Macroscopically, this reaction results in diffuse organ swelling and tumorous lesions. The macroscopic and histological differentiation from conditions mimicking IgG4-RD can be challenging. This is especially true for granulomatous diseases, such as antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The situation is further complicated by the fact that ANCAs can be positive in IgG4-RD and, vice versa IgG4 antibodies can be elevated in numerous differential diagnoses, such as infections, AAV, sarcoidosis, and malignancies. This article provides an overview of the multifaceted clinical condition of IgG4-RD with respect to the pathophysiology, diagnostic steps and treatment. Furthermore, an overview of the differential diagnoses is discussed especially with respect to granulomatous diseases.

Comment on "The risk of malignancy in patients with IgG4-related disease: a systematic review and meta-analysis" by Yu et al

With great interest, we have read the recent article “The risk of malignancy in patients with IgG4-related disease: a systematic review and meta-analysis” by Yu et al. While we have a great appreciation for the work conducted by the authors there are some methodological issues need to be considered. First, the period of articles included in the study, almost before 2013, implied that most follow-up days in these articles were earlier than the established date of a unified definition of IgG4-RD, 2011. Thus, it may lead to misclassification bias in the study. Second, IgG4-RD is a fibrous-inflammatory process that often involves multiple organs; however, malignant tumors related to IgG4-RD proposed in the study were only confined to four diseases. Therefore, we suggest adding subgroup analysis for more malignancies depending on the prevalence of IgG4-RD involved organs to ensure better clinical practice. Third, the causation between IgG4-RD and malignancy remains obscure currently. The time course for development in different malignancies varies significantly so that we cannot infer that malignancies discovered after IgG4-RD are directly relevant. With problems mentioned above, we recommend solutions to make this article more convincing.