Histopathological diagnostic value of the IgG4+/IgG+ ratio of plasmacytic infiltration for IgG4-related diseases: a PRISMA-compliant systematic review and meta-analysis

IgG4-related disease: an analysis of the clinicopathological spectrum: UK centre experience

AIM

To retrospectively evaluate the characteristic clinicopathological spectrum in patients with suspicion of IgG4-related disease (IgG4RD).

METHODS

Winpath histology database from January 2011 to April 2018 identified all suspected IgG4RD cases wherein IgG4 immunohistochemistry was performed. The histology slides were reviewed to categorise cases into Boston criteria groups-highly suggestive of IgG4RD, probable IgG4RD and insufficient evidence. Information regarding clinical data, treatment received, follow-up and serum IgG4 levels was obtained from medical records and AllScripts Patient Administration System (APAS) clinical database.

RESULTS

The study included 204 patients and the most common sites of biopsy/resection were pancreas and duodenum. The most common clinical presentation was fibroinflammatory lesion or mass/lump. On histology, 54/204 (26.47%) cases showed typical storiform fibrosis, 65/204 (32.64%) had >10 IgG4+ plasma cells per high power field and only one case showed thrombophlebitis (0.49%). There were 14/204 (6.78%) cases categorised as highly suggestive of IgG4RD; 8 of these showed high serum IgG4 levels and were managed clinically as true IgG4RD.

CONCLUSION

Histological diagnosis of IgG4RD remains challenging, as not all characteristic features are always present especially in small biopsies. Due to the novelty of its experience, fear of over diagnosis in the context of malignancy and features overlapping with diseases of similar clinical scenario, diagnosis of IgG4RD has become more puzzling. Further multicentre clinical trials/studies are advisable.

Mikulicz's disease and Küttner's tumor as manifestations of IgG4-related diseases: a review of the literature

According to a new concept for the classification and division of autoimmune diseases, Mikulicz's disease and Küttner's tumor belong to immunoglobulin G4-related diseases (IgG4-RD) and fulfil their diagnostic criteria. The aim of this study was to summarize the new classification concepts of IgG4-RD in the head and neck area and to review their clinical, histopathological and serologic criteria and the methods used in the diagnostic workup with respect to their advantages, limitations and differentiative value. The PubMed, Web of Science, Google Scholar, and Scopus databases were searched for articles published between 2009 and 2019 using the following key words: IgG4-related diseases, Mikulicz's disease, Küttner's tumor, salivary glands, xerostomia. Results of the review of the literature revealed that Mikulicz's disease and Küttner's tumor fulfil the same diagnostic criteria but may manifest different clinical symptoms which determine the choice of the different diagnostic tools.

Chronic Inflammatory Disease in the Pancreas, Kidney and Salivary Glands of English Cocker Spaniels and Dogs of Other Breeds Shows Similar Histological Features to Human IgG4-related Disease

Chronic pancreatitis (CP) is a common disease in the English cocker spaniel (ECS) and is characterized histologically by duct destruction, interlobular fibrosis and dense periductular and perivenous lymphocytic aggregates. These features are also found in human autoimmune pancreatitis type 1, part of a glucocorticoid-responsive, multiorgan syndrome, newly recognized as IgG4-related disease (IgG4-RD). Human IgG4-RD affects one or several organs, often showing a predominance of IgG4⁺ plasma cells histologically, with an IgG4⁺:total IgG⁺ plasma cell ratio of >40%. This study investigated whether ECSs with CP and/or inflammatory disease in several organs show an increase in IgG4⁺ plasma cells within affected tissues. Histological sections of pancreas, liver, kidney, salivary gland and conjunctiva were obtained from ECSs with idiopathic chronic inflammatory disease affecting those tissues. Tissue samples from age-matched dogs of other breeds with similar diseases were also sampled. Control diseased tissue samples, from dogs without a suspected immune-mediated disease, were included. A subset of ECSs and dogs of other breeds presented with disease in more than one organ. Immunohistochemistry was performed with primary reagents detecting total IgG and three of the four canine IgG subclasses (IgG2, IgG3 and IgG4). Normal sections of pancreas and liver showed an absence of labelled plasma cells of any subclass. Normal kidney and salivary gland sections showed the presence of a few labelled plasma cells (<10 plasma cells/high-power field). Fourteen tissue sections from 12 ECSs and seven sections from six dogs of other breeds showed elevated numbers of IgG4⁺ plasma cells and IgG4⁺:IgG⁺ ratios >40%. Individual dogs (ECSs and other breeds) showed marked increases in IgG4⁺ cells. There were no significant differences in the number of IgG4⁺ plasma cells between ECSs and dogs of other breeds for affected pancreas, liver, salivary glands and conjunctiva. Kidney sections had more IgG4⁺ cells, for both ECSs and dogs of other breeds, than did sections from other organs. Dogs of other breeds had significantly more IgG4⁺ plasma cells in affected kidneys than ECSs. In conclusion, several ECSs and dogs of other breeds fulfilled the histological criteria for the diagnosis of IgG4-RD, supporting the existence of a multiorgan immune-mediated disease in ECSs and some dogs of other breeds.

Malignancy and IgG4-related disease: the incidence, related factors and prognosis from a prospective cohort study in China

This prospective cohort study aims to investigate the incidence, related factors and prognosis of IgG4-related disease (IgG4-RD) with malignancies in the Chinese cohort. We prospectively analyzed the IgG4-RD patients recruited in Peking Union Medical College Hospital from January 2011 to August 2018 and identified patients diagnosed with IgG4-RD complicating malignancies. Data regarding demographics, clinical features, treatment and prognosis of IgG4-RD patients complicating malignancies were collected and compared to those of age- and sex-matched controls. Among the 587 Chinese patients with IgG4-RD, 17 malignancies were identified. Ten of them developed malignancy after the diagnosis of IgG4-RD, given a standard incidence ratio (SIR) of 2.78 (95%CI 1.33-5.12). Multivariate logistic analysis indicated that autoimmune pancreatitis (OR = 6.230, 95%CI 1.559-24.907, p = 0.010) was positively associated with malignancy, whereas eosinophilia (OR = 0.094, 95%CI 0.010-0.883, p = 0.039) was negatively related with malignancies. During a median follow-up period of 61.4 ± 26.4 months, all patients with IgG4-RD and malignancies survived. We conclude that an increased incidence of malignancy was found in Chinese IgG4-RD cohort. Autoimmune pancreatitis is a potential risk factor, whereas eosinophilia is a possible protective factor for complicating malignancies.

Bilateral orbital involvement of IgG4-related disease detected on 18F-Fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography: A Clinical Case Report

RATIONALE

IgG4-related disease (IgG4-RD) is a systemic immune-mediated fibro-inflammatory condition, which could involve multiple structures, including the pancreas, salivary glands, and lymph nodes. However, cases of IgG4-RD involving the bilateral orbits, salivary glands, submandibular glands, lymph nodes, and prostate are rare.

PATIENT CONCERNS

A 51-year-old man complaining of bilateral exophthalmos, reduced vision, and weight loss of 15 kg over 2 years presented to our department for evaluation.

DIAGNOSES

Based on the elevated serum IgG4 level, postoperative pathology, and the features of F-fluoro-2-deoxy-D-glucose (F-FDG) positron emission tomography/computed tomography (PET/CT), which revealed diffuse increased FDG uptake in many structures, he was diagnosed with IgG4-related disease involving the bilateral orbits, salivary glands, submandibular glands, lymph nodes, and prostate.

INTERVENTIONS

Because of the significant bilateral proptosis and exposure keratoconjunctivitis in the right eye, bilateral soft-tissue masses located in the orbits were resected, and the patient was started on oral methylprednisolone with gradual tapering.

OUTCOMES

The patient's symptoms gradually relieved after the operation and glucocorticoid therapy. Four months later, cranial axial CT revealed remarkable narrowing of soft-tissue masses in the bilateral orbits, and his serum IgG4 level reduced sharply.

LESSONS

IgG4-RD should be considered in cases of diffuse FDG uptake in the bilateral orbits, salivary glands, submandibular glands, lymph nodes, and prostate on PET/CT.

New insights into immune cells cross-talk during IgG4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a newly acknowledged entity, characterized by an immune-mediated fibro-inflammatory process affecting virtually all organs, with infiltration of IgG4⁺ bearing plasma cells. Until today the pathogenesis of IgG4-RD remains unknown. Treatment with anti-CD20 monoclonal antibodies efficiently induced remission and attenuated the secretory phenotype of myofibroblasts responsible of uncontrolled collagen deposition. This supports the pathogenic role of the adaptive immunity, particularly B cell compartment and B cell/T cell interaction. Latest studies have also highlighted the importance of innate immune system that has been underestimated before and the key role of a specific T cell subset, T follicular helper cells that are involved in IgG4-class-switching and plasmablast differentiation. In this review, we aim to review the most recent knowledge of innate immunity, T and B cells involvement in IgG4-RD, and introduce tertiary lymphoid organs (TLO) as a potential marker of relapse in this condition.

High level of IgG4 as a biomarker for a new subset of inflammatory bowel disease

The roles of B and plasma cells in the pathogenesis of inflammatory bowel disease (IBD) are largely unrevealed. Data on the characteristics of IgG4 in patients with IBD are scarce. In this case-control study, serum IgG4 levels were comparable between patients with IBD and healthy individuals, whereas patients with IBD had dramatically higher mucosal IgG4 counts than healthy individuals. In patients with UC, mucosal IgG4 counts were positively correlated with serum IgG4 levels, serum IgG4/IgG ratios, and the Mayo Index; serum IgG4 levels and IgG4/IgG ratios were associated with a history of intestinal surgery and medications. A significant mucosal IgG4 count was found in 33.3% of patients with IBD, whereas, elevated serum IgG4 levels were found in only 9.9% of patients with IBD. Lesions were more severe and extensive in IBD patients with high levels of serum and mucosal IgG4. High levels of serum and mucosal IgG4 decreased after treatment with glucocorticoids or other immunosuppressants. High IgG4 level may be a biomarker for a new subset of IBD. More studies are warranted to explore this new subset of IBD for personalized therapy in the future.

Diagnostic performance of serum IgG4 level for IgG4-related disease: a meta-analysis

An elevated serum IgG4 level is one of the most useful factors in the diagnosis of IgG4-related disease (IgG4-RD). In this study, we performed a meta-analysis of the published articles assessing the diagnostic accuracy of serum IgG4 concentrations for IgG4-RD. The databases of MEDLINE/PubMed, EMBASE and Web of Science were systematically searched for relevant studies. Sensitivities and specificities of serum IgG4 in each study were calculated, and the hierarchical summary receiver operating characteristic (HSROC) model with a random effects model were employed to obtain the individual and pooled estimates of sensitivities and specificities. In total, twenty-three studies comprising 6048 patients with IgG4-RD were included in the meta-analysis. The pooled sensitivity was 85% with a 95% confidence interval (CI) of 78-90%; the pooled specificity was 93% with a 95% CI of 90-95%. The HSROC curve for quantitative serum IgG4 lies closer to the upper left corner of the plot, and the area under the curve (AUC) was 0.95 (95% CI 0.93, 0.97), which suggested a high diagnostic accuracy of serum IgG4 for the entity of IgG4-RD. Our study suggests that serum IgG4 has high sensitivity and specificity in the diagnosis of IgG4-RD.

Overview of IgG4-Related Tubulointerstitial Nephritis and Its Mimickers

Tubulointerstitial nephritis (TIN) is the most common form of renal involvement in IgG4-related disease. It is characterized by a dominant infiltrate of IgG4-positive plasma cells in the interstitium and storiform fibrosis. Demonstration of IgG4-positive plasma cells is essential for diagnosis, but the number of IgG4-positive cells and the ratio of IgG4-positive/IgG-positive plasma cells may vary from case to case and depending on the methods of tissue sampling even in the same case. IgG4-positive plasma cells can be seen in TIN associated with systemic lupus erythematosus, Sjögren syndrome, or anti-neutrophil cytoplasmic antibody–associated vasculitis, which further add diagnostic confusion and difficulties. To have a more clear view of IgG4-TIN and to delineate differential points from other TIN with IgG4-positive plasma cell infiltrates, clinical and histological features of IgG4-TIN and its mimickers were reviewed. In the rear part, cases suggesting overlap of IgG4-TIN and its mimickers and glomerulonephritis associated with IgG4-TIN were briefly described.