The changing faces of IgG4-related disease: Clinical manifestations and pathogenesis

A Case Report of a Challenging Disease: Immunoglobulin G4-Related Disease With Acute Kideny Injury

Immunoglobulin G4-related disease (IgG4-RD), which was initially identified as a type of autoimmune pancreatitis around the year 2000, is now widely acknowledged to be a systemic sickness. Based on both general and organ-specific criteria, alongside laboratory measurements of IgG4-subtype, the diagnosis is made. The diagnosis requires, however, a heightened index of suspicion, especially given the nonspecific clinical presentation. In addition to this, the symptoms may be "disseminated" in time and the multitude of organ-system involvement may seem initially unrelated. Furthermore, IgG4 levels may be falsely normal especially during the first presentation of IgG4-RD. We report a case of a 33-year-old male who was referred by his general practitioner (GP) to the fast access nephrology clinic due to elevated creatinine and fatigue, which was found after the patient had undergone some investigations at the GP office. He had history of atopic dermatitis and a prior admission for acute pancreatitis of unknown cause and recent bilateral anterior uveitis treated with steroid eyedrops. His urinalysis showed one to two granular casts per high-power field (HPF), and his creatinine was 262 µmol/L (previously normal). Three main differential diagnoses were considered given the patient's history: sarcoidosis, tubulointerstitial nephritis with uveitis (TINU) and IgG4-related disorder. Investigations were undertaken in that regard showing elevated serum IgG4 levels (2.7 times upper-limit of normal). Renal biopsy demonstrated tubulointerstitial nephritis (TIN) with 30 IgG4-positive plasma cells per HPF. Given the patient's presentation over time, a diagnosis of IgG4-TIN was considered. The patient was treated with high-dose steroids and has shown signs of improvement of both his renal and ocular problems. The uniqueness of the case is reflected through the fact that IgG4-renal disease is usually diagnosed in patients with an already established manifestation of another organ, whilst in our patient the renal involvement led to establishing IgG4-RD. It is also important to note that, in spite of initially negative serum IgG4 levels, the diagnosis still needs to be considered especially if multisystem involvement is present (as in this case).

Autoimmune pancreatitis and pancreatic cancer: Epidemiological aspects and immunological considerations

Ordinary chronic pancreatitis is a well-known risk factor for pancreatic cancer, whereas such an association with autoimmune pancreatitis (AIP) is widely debated. Due to the rarity of the latter disorder, there are few specific clinical and epidemiological studies investigating the relation between AIP and pancreatic cancer, which do not seem to support it. However, these studies are affected by several limitations and, therefore, a link between AIP (and, specifically, type 1 AIP) and pancreatic cancer cannot be ruled out definitively on this basis. Moreover, several immunopathological aspects of type 1 AIP and, in general, immunoglobulin G4-related disease can create an immunological context that may impair the tumoral immunosurveillance and promote the pancreatic carcinogenesis and its progression. In detail, Th2 immunological dominance, type 2 macrophage polarization and basophil infiltration observed in type 1 AIP, may play a permissive role in creating a favorable immunological environment for pancreatic carcinogenesis, in addition to the immunosuppressive therapies that can be used in these patients.

Allergic Aspects of IgG4-Related Disease: Implications for Pathogenesis and Therapy

IgG4-related disease (IgG4-RD) is a rare systemic fibroinflammatory disease frequently associated with allergy. The pathogenesis of IgG4-RD is poorly understood, and effective therapies are limited. However, IgG4-RD appears to involve some of the same pathogenic mechanisms observed in allergic disease, such as T helper 2 (Th2) and regulatory T cell (Treg) activation, IgG4 and IgE hypersecretion, and blood/tissue eosinophilia. In addition, IgG4-RD tissue fibrosis appears to involve activation of basophils and mast cells and their release of alarmins and cytokines. In this article, we review allergy-like features of IgG4-RD and highlight targeted therapies for allergy that have potential in treating patients with IgG4-RD.

Long-Term Outcomes of Tamoxifen Citrate Therapy and Histo- and Immunopathological Properties in Riedel Thyroiditis

BACKGROUND

Riedel thyroiditis (RT) is a rare form of thyroiditis; thus, data about the disease course and treatment options are limited. Therefore, we aimed to assess the clinical, serological, radiological, and histopathological features, as well as short- and long-term follow-up of RT patients under glucocorticoid (GC) and tamoxifen citrate (TMX). Parameters related to IgG4-related diseases (IgG4-RD) were also investigated.

METHODS

Eight patients with RT diagnosed between 2000 and 2019 were enrolled. Data were collected in a retrospective and prospective manner. The diagnosis was confirmed with histopathological features in all patients. Results of the treatment with GCs on short- to mid-term, followed by TMX in the long term, were evaluated.

RESULTS

The mean age at diagnosis was 40.5 ± 6.8 years; female predominance was observed (F/M:7/1). Parameters related to IgG4-RD, like increase in IgG4 serum levels, total plasmablast counts, and IgG4+ plasmablasts, were negative in most of our patients in both active and inactive states of the disease. Likewise, an increased ratio of IgG4/IgG-positive plasma cells >40% could only be observed in 2 cases. GCs followed by TMX were given to the patients with an over-all median follow-up time of 67 (8-216) months. All the patients considerably improved clinically and had a reduction in the size of the mass lesion on GCs, followed by TMX therapy. None of the patients had a recurrence under TMX therapy for a median period of 18.5 (7-96) months.

CONCLUSION

Even though RT is suggested to be a member of IgG4-RD, serologic or histological evidence of IgG4 elevation or positivity is only useful for diagnosis and follow-up of RT. The diagnosis should be based on clinical and radiological evidence and confirmed by histopathology. GCs are effective for initial treatment, and TMX is a successful and safe therapeutic option for long-term maintenance therapy.

Mediastinal IgG4-Related Disease Manifesting as Superior Vena Cava Syndrome

Immunoglobulin G4 (IgG4)-related disease was first identified as a systemic condition in 2003 when extrapancreatic manifestations were identified in patients with autoimmune pancreatitis. Its peak incidence occurs in the fifth or sixth decades of life. Isolated extraaortic mediastinal involvement is extremely rare. This report describes a case of isolated extraaortic mediastinal IgG4-related disease encasing the superior vena cava (SVC) and manifesting as SVC syndrome in a 25-year-old man with no personal or family history of autoimmune disease. Resection with SVC reconstruction was performed.

Pericardial immunoglobulin G4-related inflammatory pseudotumor after right upper lobectomy for lung cancer

A 75‐year‐old woman underwent thoracoscopic right upper lobectomy for lung cancer. A histopathological examination showed adenocarcinoma, pT1aN0M0 stage IA1. At six months after surgery, chest computed tomography (CT) revealed pericardial nodules that had not been detected before pulmonary resection. Postoperative CT performed two months later revealed that the nodules were growing and F¹⁸ fluorodeoxyglucose‐positron emission tomography showed a maximum standardized uptake of 9.87. Blood tests revealed no elevated tumor markers, with the exception of a mildly elevated interleukin‐2. Based on the above results, thoracoscopic biopsy was performed due to the suspected recurrence of lung cancer or malignant lymphoma. The histopathological examination of the nodule revealed immunoglobulin G4 (IgG4)‐related inflammatory pseudotumor. The serum IgG4 levels were elevated (358 mg/dL, normal: 4.5–117.0 mg/dL). No additional treatment was required because all nodules were observed to have disappeared naturally on a follow‐up CT scan performed two months after the surgical biopsy. The patient has been followed‐up for two years without recurrence.

Key points

Significant findings of the study

We report a case of pericardial immunoglobulin G4‐related inflammatory pseudotumor that appeared after right upper lobectomy for lung cancer, and which naturally disappeared without any treatment.

What this study adds

There was an immunoglobulin G4‐related inflammatory pseudotumor which appeared as multiple nodules in the pericardial space, and this should be kept in mind when considering the differential diagnosis of intrapericardial nodules.

IgG4-related disease: How to place it in the spectrum of immune-mediated and rheumatologic disorders?

IgG4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory disorder that results from massive expansion of polyclonal IgG4-switched B and/or plasma cells. It can virtually affect all organs and its diagnosis relies on clinical, serological and histopathological criteria. The role of autoimmunity and adaptive immune system in IgG4-RD is reflected in plasmablast differentiation, germinal center formation and IgG4 production induced by CD4+ cells expressing CD40 ligand. IgG4-RD has been considered to be a Th2/Treg-driven disorder, but follicular helper T cells are important in driving the IgG subclass switch. Prompt clinical responses to rituximab, human leukocyte antigen (HLA) associations and the presence of autoantibodies also point to the importance of adaptive immune system. However, innate immunity may induce storiform fibrosis through T-cell independent responses as a consequence of toll-like receptors activation by microbe-and damage-associated molecular patterns, while macrophages and basophils also appear to have a significant role in IgG4-RD pathogenesis. Allergic mechanisms may drive IgG4-RD, but only a subgroup has elevated IgE serum levels and peripheral eosinophilia. Finally, the 2012 revised Chapel Hill Consensus Conference nomenclature pointed IgG4-RD as a cause of large-vessel vasculitis. This review aims to discuss how to place IgG4-RD in the spectrum of immune-mediated and rheumatologic disorders.

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

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

Pulmonary vascular involvement of IgG4-related disease: Case series with a PRISMA-compliant systemic review

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is a recently recognized, immune-mediated chronic fibrotic inflammation that can involve almost all organs, causing tumefaction and dysfunction. Its presence in pulmonary circulation is underestimated and has not yet been investigated.

OBJECTIVES

We describe a representative IgG4-RD patient with pulmonary artery stenosis and pulmonary embolism, leading to reversible pulmonary hypertension. Literature review of IgG4-RD with pulmonary circulation involvement was conducted.

DATA SOURCES

References for this review were identified through searches via PubMed, EBSCO, and Web of Science for published articles before November 2016.

RESULTS

There were 15 published cases of IgG4-RD with pulmonary vascular involvement, 3 with pulmonary arteritis, 2 with pulmonary artery aneurysm, 3 with pulmonary artery stenosis, 1 with obliterative phlebitis, and 1 with pulmonary embolism. Possible immunity and inflammation mechanisms were summarized.

CONCLUSIONS

IgG4-RD with pulmonary vascular involvement is rare. Echocardiogram and contrast-enhanced chest CT are helpful to screen the disease. Clinical manifestations were found from asymptomatic to dyspnea or even syncope. And nearly all cases had more than 1 organ affected, with significantly increased serum IgG4 levels. PET/CT aided in identifying affected organs and determining candidate biopsy sites. More awareness is urged to evaluate the pulmonary vascular manifestations of this disease.

Thymic inflammatory pseudotumor with multilocular thymic cyst caused by immunoglobulin G4-related disease

A 44-year-old man was referred to our hospital after an anterior mediastinal tumor was noted on computed tomography during follow-up observation after left testicular seminoma resection. Chest computed tomography revealed an enhanced mass measuring 33 x 16 x 15 mm at the anterior mediastinum. Chest magnetic resonance imaging revealed high signal intensity on T2-weighted imaging, and F¹⁸  fluorodeoxyglucose-positron emission tomography showed a maximum standardized uptake of 12.45. Laboratory tests revealed no elevated tumor markers, except for mildly elevated interleukin-2. Based on these results, complete resection was performed under suspicion of a malignant tumor, mediastinal metastasis of seminoma, or malignant lymphoma. An extended thymectomy with partial merger pericardial resection was performed using a subxiphoid approach. Small nodules and multiple thymic cysts were observed the thymus in addition to the main mass. Microscopic examination of the tumor revealed fibrosis, lymphocyte infiltration with lymphoid follicular hyperplasia, and hyperplasia of the thymus. Numerous immunoglobulin G4 (IgG4)-positive plasma cells were found on immunohistochemical staining. The ratio of IgG4 to total IgG was approximately 60%. We ultimately diagnosed the patient with a thymic inflammatory pseudotumor with multilocular cyst caused by IgG4-related disease.

Immunoglobulin G4-Related Disease Mimicking an Anterior Mediastinal Tumor

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated collection of disorders that were once thought to be unrelated but are increasingly being recognized as a single entity. The tumor-like swelling of the involved organ, a storiform pattern of fibrosis, and a serologic elevation of IgG4 can lead to the diagnosis of IgG4-RD. The usual organs affected are the pancreas, biliary tract, and salivary and lacrimal glands. There have been few reports of intrathoracic cases, which usually have pulmonary lesions. We here report a case of IgG4-RD of the anterior mediastinum in the form of a mass, a rare entity, the second such patient described in the literature to date.

Mastitis associated with Sjögren's syndrome: a series of nine cases

Sjögren's syndrome is well known to target exocrine glands, especially lacrimal and salivary glands, which share with mammary glands anatomical, histological, and immunological features. Herein, we investigated the mammary involvement in patients with Sjögren's syndrome and compared the histological findings with minor salivary gland involvement. We reviewed the charts of patients with Sjögren's syndrome (followed in Montpellier University Hospital, between January 2000 and January 2015), in whom minor salivary gland and mammary tissues were available. Two expert pathologists analysed retrospectively these tissues in order to identify inflammatory patterns. Immunohistochemical stainings were performed to precise leucocyte distribution. Sixteen Sjögren's syndrome patients with available salivary and breast tissue samples were included. All were women, with a median age of 60.1 ± 11.3 years at Sjögren's syndrome diagnosis. Mammary biopsy was conducted because of breast symptoms in 6 patients and following imaging screening strategies for breast cancer in 10 patients. Nine patients exhibited an inflammatory breast pattern (lymphocytic infiltrates or duct ectasia), close to minor salivary gland histological findings. Immunohistochemical stainings (n = 5) revealed B and T cell infiltrates within breast tissue, with a higher proportion of T CD4+ cells, but no IgG4-secreting plasma cells were found. This is the first series to describe breast inflammatory patterns in Sjögren's syndrome. Mastitis is in line with the classical involvement of exocrine glands in this disease. These findings are consistent with the literature data considering Sjögren's syndrome as an "autoimmune epithelitis".

Pancreatitis after human papillomavirus vaccination: a matter of molecular mimicry

A 20-year-old man developed severe abdominal pain 1 week after being vaccinated with the first dose of quadrivalent human papillomavirus (HPV) vaccine (Gardasil^®). Despite ongoing symptoms of nausea and pain, he received the second dose of the vaccine. Only 10 days later, laboratory results revealed significantly elevated pancreatic enzymes, and with concomitant abdominal pain and vomiting, he was diagnosed with acute pancreatitis. This case of acute pancreatitis after HPV vaccination is not a novel entity. Although confirming the relationship between pancreatitis and vaccine is challenging, some factors suggest a possible link, including the positive re-challenge upon repeated exposure to the vaccine, HPV vaccine as probable causal relationship to other autoimmune diseases and a probable mechanism of molecular mimicry. In conjunction with aluminum adjuvant, the induction of immunity through molecular mimicry may potentially culminate in production of cytotoxic autoantibodies with a particular affinity for pancreatic acinar cells.

IgG4-Related Disease: A Reminder for Practicing Pathologists

IgG4-related disease (IgG4-RD) is a systemic autoimmune fibroinflammatory disease that produces sclerotic, tumefactive masses containing dense lymphoplasmacytic infiltrates rich in immunoglobulin (Ig) G4+ plasma cells. Initially characterized as a form of autoimmune pancreatitis, the distinctive histopathology of IgG4-RD has now been described in almost every organ system. However, because the clinical manifestations of IgG4-RD are diverse and nonspecific, the disease may go unsuspected until a biopsy or resection specimen is obtained to diagnose a presumed malignancy. Pathologists thus play a key role in the diagnosis of IgG4-RD, and familiarity with its histopathologic features is essential to preventing the irreversible comorbidities associated with this treatable disease. This brief review outlines the epidemiology, clinical manifestations, and histopathology of IgG4-RD, with the aim of furthering pathologists' awareness of and ability to diagnose this disorder.

The importance of IgG4 screening in patients diagnosed with primary sclerosing cholangitis in the past: A case rediagnosed as IgG4-SC after 10 years

RATIONALE

While primary sclerosing cholangitis (PSC) has been recognized for decades, immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) has been correctly diagnosed only in recent years. PSC and IgG4-SC show similar clinical symptoms, serologic markers, and imaging results, but the treatment strategies and prognosis of patients differ.

PATIENT CONCERNS

Here, we present the case report of a patient diagnosed with PSC for 10 years and rediagnosed with IgG4-SC recently, to emphasize the importance of screening serum IgG4 levels in patients with previous diagnosis of PSC.

DIAGNOSES

A 57-year-old woman with 10-year history of PSC was hospitalized due to pruritus. In 2004, the patient underwent cholecystectomy and cholangioenterostomy because of unexplained jaundice with pancreatic swelling. In the last 10 years, her liver enzyme levels were continuously elevated. The latest liver function profile showed elevated alanine aminotransferase, aspartate aminotransferase, and total bilirubin. IgG4 was 3.69 (0.03-2.01 g/L). Immunohistochemical staining of the surgical specimen showed >10 IgG4-positive plasma cells per high-power field, and IgG4+/IgG+ plasma cells >40%.

INTERVENTIONS AND OUTCOMES

She was treated with prednisone 40 mg once-daily and the dose was gradually tapered. The patient remains well after 18 months.

LESSONS SUBSECTIONS

Patients with IgG4-SC may be misdiagnosed as PSC due to lack of IgG4 screening. It is important to perform IgG4 screening in patients diagnosed as PSC. Steroid is effective to prevent disease progression in these patients.

IgG4-related systemic disease presenting with pleural effusion, ascites and dilated cardiomyopathy

PURPOSE

We report the case of a patient with IgG4-related disease with multiple organ involvement, especially myocardium, that was successfully treated with prednisone.

METHODS

We performed several serological tests, electrocardiogram, echocardiography, computed tomography and inguinal lymph node biopsy.

RESULTS

We diagnosed the patient with IgG4-related disease by the elevated serum IgG4 level and histological lymph node findings.

CONCLUSIONS

This is the first reported case of IgG4-related disease with dilated cardiomyopathy.

The great imitator: IgG4 periaortitis masquerading as an acute aortic syndrome on computed tomographic angiography

We present the case of a 52-year-old woman who presented to the emergency department with chest and neck pain. Initial cervical spine magnetic resonance imaging shows an abnormal flow void in the left vertebral artery, which prompted a computed tomographic angiogram. This demonstrated a hyperdense thickened ascending aortic wall, which extended into the great vessel origins. Clinically and radiographically interpreted as an acute aortic syndrome and/or intramural hematoma, the patient underwent ascending aortic repair with graft. An unusual aortic and/or periaortic mass was encountered in surgery and final pathology demonstrated IgG4 periaortitis. A rare clinical disease, IgG4-mediated processes are often mimickers of other pathologic entities and frequently lead to misdiagnosis. All pathologically similar, IgG4-mediated disease processes can involve the pancreas, salivary glands, orbits, retroperitoneum, and the vasculature.

Detection of Polyclonal Increases in Immunoglobulin G4 Subclass by Distinct Patterns on Capillary Serum Protein Electrophoresis: Diagnostic Pitfalls and Clinical Observations in a Study of 303 Cases

OBJECTIVES

Autoimmunity, hypersensitivity, and the recently recognized set of syndromes collectively termed immunoglobulin G4-related disease (IgG4-RD) may be associated with increased serum IgG4 levels. We reviewed our experience detecting increased IgG4 by distinct serum protein electrophoresis (SPEP) patterns.

METHODS

We studied 303 capillary SPEP cases with dome-like anodal γ changes and increased measured serum IgG4.

RESULTS

IgG4 ranged from 208 to 6,670 mg/dL (normal, <201 mg/dL). Seventeen of 91 cases evaluated by immunosubtraction appeared monotypic (16 κ, 1 λ), but all five cases further analyzed by isoelectric focusing appeared polyclonal. Six cases with markedly increased IgG4 had presumptive evidence of IgG4-RD. Sixteen of 45 assessed patients had autoantibodies.

CONCLUSIONS

Increased polyclonal IgG4 has a characteristic SPEP pattern that may mimic monoclonal gammopathy, even on immunosubtraction. κ Pseudo-restriction might reflect the naturally high κ/λ ratio of the IgG4 subclass. Autoantibodies were common, and the greatest IgG4 increases had clinical features of IgG4-RD.

Immunohistochemical analysis of IgA expression differentiates IgG4-related disease from plasma cell-type Castleman disease

Plasma cell-type Castleman disease (PCD) is often encountered when differentiating IgG4-related disease (IgG4-RD). Given that serum IgA is often elevated in Castleman disease, we investigated whether IgA expression levels in histological specimens can be used to differentiate between the two diseases. Lymph node lesions obtained from 12 IgG4-RD and 11 PCD patients were analysed by immunohistochemistry with anti-IgG, -IgG4, and -IgA antibodies. In addition to all 12 cases of IgG4-RD, 8/11 cases (72.7 %) of PCD also met the diagnostic criteria of IgG4-RD (serum IgG4 ≥135 mg/dl and IgG4/IgG-positive cells ≥40 %). IgA-positive cells were sparsely and densely distributed in IgG4-RD and PCD cases, respectively. The median number of IgA-positive cells ± SD in all 12 cases of IgG4-RD was 31 ± 37 cells per three high-powered fields (3HPFs) (range 4-118 cells/3HPFs). In contrast, the median number of IgA-positive cells, which was significantly higher in all 11 cases of PCD, was 303 ± 238 cells/3HPFs (range 74-737 cells/3HPFs) (P < 0.001). In conclusion, our findings indicate that in cases where serum analysis-based data are unavailable, anti-IgA immunostaining can be used for differential diagnosis of IgG4-RD.

Enhanced IgG4 production by follicular helper 2 T cells and the involvement of follicular helper 1 T cells in the pathogenesis of IgG4-related disease

Background

The aim of this study was to elucidate the function of circulating follicular helper T (Tfh) cell subsets in helping B cells in patients with active, untreated IgG4-related disease (IgG4-RD) and determine their relationship with disease activity.

Methods

Seventeen consecutive patients with active, untreated IgG4-RD, 20 with primary Sjögren syndrome (pSS), 5 with multicentric Castleman’s disease (MCD), and 12 healthy controls (HC) were enrolled. Tfh cell subset function was evaluated by co-culture with naïve B cells in vitro. Activated Tfh cell subsets were defined as a CCR7^lowPD-1^high subset among Tfh cell subsets. Disease activity was evaluated by IgG4-RD responder index (IgG4-RD RI) score.

Results

The number of Tfh2 cells was significantly higher in IgG4-RD compared to pSS, MCD, or HC, and correlated with serum IgG4 level or the number of plasmablasts. In vitro, Tfh2 cells more efficiently induced the differentiation of naïve B cells into plasmablasts compared to Tfh1 or Tfh17 cells. Of note, while IgG production in culture supernatants of Tfh2 cells was comparable between IgG4-RD and HC, IgG4 production was significantly higher with Tfh2 cells from patients with IgG4-RD than in those from HC. Accordingly, the IgG4:IgG ratio in culture supernatants was also significantly higher with Tfh2 cells from IgG4-RD compared to HC. Moreover, the number of activated Tfh2 cells was higher in IgG4-RD compared to pSS, MCD, or HC, and strongly correlated with IgG4-RD RI score in the baseline active phase. Particularly, the number of activated Tfh2 cells was associated with the number of affected organs and serum IgG4 level. Importantly, the number of activated Tfh2 cells was decreased after glucocorticoid treatment and paralleled disease improvement. Moreover, the number of activated Tfh1 cells was also increased in IgG4-RD compared to pSS, MCD, or HC, correlating with IgG4-RD RI score, but not with serum IgG4 level.

Conclusions

Tfh2 cells, but not Tfh1 or Tfh17 cells, induce the differentiation of naïve B cells into plasmablasts and enhanced production of IgG4 in patients with active, untreated IgG4-RD. Furthermore, activated Tfh2 cells reflect disease activity, suggesting the involvement of this T cell subset in the pathogenesis of IgG4-RD. Interestingly, the number of activated Tfh1 cells was also increased in IgG4-RD, correlating with disease activity but not with serum IgG4 level, suggesting the involvement of Tfh1 cells but not in the process of IgG4 production in patients with IgG4-RD.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1064-4) contains supplementary material, which is available to authorized users.

Non-infectious environmental antigens as a trigger for the initiation of an autoimmune skin disease

Pemphigus represents a group of organ specific autoimmune blistering disorders of the skin mediated by pathogenic autoantibodies with well-defined antigenic targets. While most of these diseases are sporadic, endemic forms of disease do exist. The endemic form of pemphigus foliaceus (also known as fogo selvagem, FS) exhibits epidemiological features that suggest exposure to hematophagous insect bites are a possible precipitating factor of this autoimmune disease, and provides a unique opportunity to study how environmental factors contribute to autoimmune disease development. FS patients and healthy individuals from endemic regions show an autoreactive IgM response that starts in early childhood and becomes restricted to IgG4 autoantibodies in FS patients. In searching for triggering environmental antigens, we have found that IgG4 and IgE autoantibodies from FS patients cross-react with a salivary antigen from sand flies. The presence of these cross-reactive antibodies and antibody genetic analysis confirming that these antibodies evolve from the same naïve B cells provides compelling evidence that this non-infectious environmental antigen could be the initial target of the autoantibody response in FS. Consequently, FS serves as an ideal model to study the impact of environmental antigens in the development of autoimmune disease.

Optic nerve involvement in immunoglobulin G4-related disease: A case report

The present study reports the case of a 79-year-old woman manifesting skin changes, a pancreatic neoplasm, enlarged lymph nodes, an eyelid mass and interstitial pneumonia over a 30-year period. At 2 months before admission to our hospital, the patient presented rapid vision loss in the left eye. Left optic nerve atrophy with a focal hyperintense lesion was documented on a T2-weighted magnetic resonance imaging (MRI) scan, and visual evoked potential implicit times were prolonged. Elevated serum immunoglobulin G4 (IgG4) concentrations and the presence of enriched IgG4-positive plasma cells in the lymph nodes established the diagnosis of IgG4-related optic neuropathy. Following oral treatment with methylprednisolone, the serum IgG4 levels fell to normal levels, and the left eye visual acuity improved to a level that remained stable over a 1-year follow-up period. After 4 months of methylprednisolone administration, the optic nerve appeared to be normal on an MRI scan. Prior reports on IgG4-related optic neuropathy involved an infiltrating mass, which was not observed in the present case. Similarly to the current study, previous cases have responded to treatment with glucocorticoids, indicating that the underlying mechanism of the disease may be common.

IgG4-related disease: a systematic review of this unrecognized disease in pediatrics

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibro-inflammatory condition with an unclear pathophysiological mechanism affecting different parts of the body. If untreated, the disease can lead to fibrosis and irreversible organ damage. IgG4-RD mostly has been described in adults, hence it is generally unknown among pediatricians. This systematic search of the literature provides an overview of all reports published on IgG4-RD in children in order to create awareness of IgG4-RD in pediatrics and to emphasize the broad clinical presentation of this disease.

METHODS

A systematic literature search of Embase, Medline, Web-of-Science, PubMed publisher, Cochrane and Google Scholar was performed for case reports on IgG4-RD in children.

RESULTS

Of total 740 articles identified by the search, 22 case reports including 25 cases of IgG4-RD in children were found. The median age of the children was 13 years, of which 64 % were girls. IgG4-related orbital disease (44 %) and autoimmune pancreatitis type 1/IgG4-related pancreatitis (12 %) predominantly occurred. Less frequently, other manifestations as pulmonary manifestation, cholangitis and lymphadenopathy were also found. Almost all cases were histologically proven. Prednisone was the first choice of treatment leading to favorable clinical response in 83 % of the cases. Maintenance therapy with steroid sparing agents was required in 43 % of the cases needing therapy. Rituximab was successful in all 4 cases, whereas, the disease modifying rheumatic drugs (DMARDs) mycophenolate mofetil, azathioprine and methotrexate were effective in almost 50 % of the cases.

CONCLUSION

IgG4-RD in children is a generally unknown disease among pediatricians, but several pediatric cases have been described. Prednisone is the first choice of treatment leading to disease remission in the majority of the cases. DMARDs and rituximab are alternative effective steroid sparing agents with more positive evidence for the latter.

Serum Concentrations of IgG4 in the Spanish Adult Population: Relationship with Age, Gender, and Atopy

Background and Aim

Serum IgG4 concentrations are commonly measured in clinical practice. The aim of this study was to investigate serum IgG4 concentrations in adults and their potential relationship with demographic, lifestyle, metabolic, and allergy-related factors.

Methods

Serum IgG4 concentrations were measured with a commercial assay in 413 individuals (median age 55 years, 45% males) who were randomly selected from a general adult population.

Results

Median IgG4 concentration was 26.8 mg/dL. Five out of the 413 individuals (1.2%) exhibited IgG4 concentrations >135 mg/dL, and 17 out of 411 (4.1%) exhibited an IgG4/total IgG ratio >8%. Serum IgG4 concentrations were significantly higher in males than in females and decreased with age. After adjusting for age and sex, serum IgG4 concentrations were not significantly influenced by alcohol consumption, smoking or common metabolic abnormalities (obesity and the related metabolic syndrome). Serum IgG4 concentrations were not significantly correlated with serum concentrations of proinflammatory cytokines and inflammation markers. Serum IgG4 concentrations were significantly correlated with IgE concentrations. Serum IgG4 concentrations tended to be higher in atopics (individuals with IgE-mediated sensitization to aeroallergens) than in non-atopics, particularly among atopics without respiratory symptoms. Serum IgG4 concentrations were not significantly correlated with total eosinophil blood count. Cases of IgG4-related disease were neither present at baseline nor detected after a median of 11 years of follow-up.

Conclusions

Studies aimed at defining reference IgG4 values should consider partitioning by age and sex. Further studies are needed to confirm the potential influence of atopy status on serum IgG4 concentrations.

Neck abscess: An unusual clinical presentation of immunoglobulin G4 related disease

Immunoglobulin G4 related disease (IgG4-RD) is a systemic fibroinflammatory disease that can affect almost any organ. Only a few cases of IgG4-RD have been reported to present with cervical lymphadenopathy and none with neck abscesses. We report a case in a patient with bilateral neck mass and bilateral neck abscesses. The patient underwent bilateral neck incision for drainage of the abscesses on two occasions, followed by a neck dissection after a third recurrence. Immunohistochemistry of the specimen revealed IgG4-RD. Although surgery is not the recommended first-line approach for IgG4-RD, only a neck dissection enabled clinical resolution of the lesions in our patient.

LEVEL OF EVIDENCE

NA Laryngoscope, 126:1114-1116, 2016.

Diagnostic Performance of Serum IgG4 Levels in Patients With IgG4-Related Disease

The aim of this study is to study the clinical features and diagnostic performance of IgG4 in Chinese populations with IgG4-related diseases (IgG4-RDs).The medical records of 2901 adult subjects who underwent serum IgG4 level tests conducted between December 2007 and May 2014 were reviewed.Serum concentrations of IgG4 were measured in 2901 cases, including 161 (5.6%) patients with IgG4-RD and 2740 (94.4%) patients without IgG4-RD (non-IgG4-RD group). The mean age of the IgG4-RD patients was 58.4 ± 16.1 years (range: 21-87), and 48 (29.8%) were women. The mean serum IgG4 level was significantly much higher in IgG4-RD patients than in non-IgG4-RD (1062.6 vs 104.3 mg/dL, P < 0.001) participants. For IgG4 >135 mg/dL, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), likelihood ratio (LR)+, and LR- were 86%, 77%, 18%, 99%, 3.70, and 0.19, respectively. When the upper limit of normal was doubled for an IgG4 >270 mg/dL, the corresponding data were 75%, 94%, 43%, 98%, 12.79, and 0.26, respectively. For IgG4 >405 mg/dL (tripling the upper limit of normal), the corresponding data were 62%, 98%, 68%, 98%, 37.00, and 0.39, respectively. When calculated according to the manufacturer's package insert cutoff (>201 mg/dL) for the diagnosis of IgG4-RD, the corresponding sensitivity, specificity, PPV, NPV, LR+, and LR- were 80%, 89%, 29%, 99%, 7.00, and 0.23, respectively. For IgG4 >402 mg/dL (>2× the upper limit of the normal range), the corresponding data were 62%, 98%, 68%, 98%, 36.21, and 0.39, respectively. For IgG4 >603 mg/dL (>3× the upper limit of the normal range), the corresponding data were 50%, 99%, 84%, 97%, 90.77 and 0.51, respectively. The optimal cutoff value of serum IgG4 (measured by nephelometry using a Siemens BN ProSpec instrument and Siemens reagent) for the diagnosis of IgG4-RD was 248 mg/dL, the sensitivity and specificity were 77.6% and 92.8%, respectively.The present study demonstrated that 2 or 3 times the upper limit of the manufacturer's reference range of the IgG4 level was a useful marker for the diagnosis of various types of IgG4-RD and the optimal cutoff level was 248 mg/dL.

Structural properties of adenovirus DNA's

The current study presents the case of a 9-year-old Chinese boy who presented with eosinophilia and elevated serum levels of immunoglobulin G4 (IgG4). A bone marrow puncture identified an elevated eosinophil rate of 23% (normal range, <5%), which indicated eosinophilia. However, gene analysis, fluorescent in situ hybridization and other examinations, including bone marrow aspiration, blood routine, auto-antibody tests and parasitic and allergens screening, contradicted a diagnosis of secondary or clonal eosinophilia. Furthermore, the patient exhibited multiple lymph node swelling and a lymph biopsy strongly indicted a pathological diagnosis of IgG4-related disease (IgG4-RD). His peripheral blood flow cytometry confirmed an elevated count of plasmablasts, which is specific to IgG4-RD. The patient responded well to therapy with prednisone and remained healthy in all follow-ups. By taking all these factors into consideration, the boy was diagnosed with IgG4-RD. It is difficult to distinguish IgG4-RD from hypereosinophilic syndrome and the potential association between the two remains unclear. However, the present case study serves as a reminder that IgG4-RD may occur in children and medical professionals should not neglect this possibility.