IgG4-related disease: association between chronic rhino-sinusitis and systemic symptoms

New insights into chronic rhinosinusitis associated with IgG4-related disease

IgG4-related disease (IgG4-RD) is a chronic inflammatory disorder characterized by elevated IgG4 serum levels, abundant IgG4-positive plasmacyte infiltration, and fibrosis of various organs, including the head and neck. We aimed to provide an overall review of IgG4-RD in the sinonasal region and propose a novel entity and criteria of chronic rhinosinusitis (CRS) associated with IgG4-RD as "IgG4-CRS," a distinct manifestation of IgG4-RD in the sinonasal region. Sinonasal involvement has been increasingly recognized; however, this region is not included in the classic IgG4-RD-affected organs. The clinical features of IgG4-CRS, including its prevalence and relationship with allergies and olfactory disturbances, have also been explored. Serum IgG4 levels and IgG4-positive plasma cell infiltrations, crucial diagnostic factors, have been discussed in association with IgG4-CRS pathogenesis. Fibrosis, a hallmark of IgG4-RD, is observed in sinonasal tissues; however, typical fibrosis, such as storiform fibrosis, is not usually found. Mimics or complications in eosinophilic CRS (ECRS) and antineutrophil cytoplasmic antibody-associated vasculitis (AAV) are highlighted. Treatment often involves typically effective glucocorticoids. Organ-specific diagnostic criteria for the sinonasal region have not currently been established. Hence, this review aims to foster awareness and understanding of IgG4-CRS among ENT physicians and to provide a basis for future research and diagnostic refinement.

Proliferative features of IgG4-related disease

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

Advancements in diagnosing IgG4-related disease of the head and neck: Navigating diagnostic pitfalls

IgG4-related disease (IgG4-RD) is an immune-mediated condition affecting nearly any organ. This review focuses on the nuances of diagnosing IgG4-RD affecting the head and neck. Salivary gland involvement, especially of the submandibular glands, often permits a definitive diagnosis on biopsy. However, elevated IgG4+ plasma cells are nonspecific and can be seen in chronic sialadenitis, lymphoma, and other mimics. Careful correlation of clinical and pathological findings is essential. Given the significant overlap with chronic sinusitis, IgG4-RD of the sinonasal region is difficult to diagnose histologically. Laryngeal and pharyngeal involvement appears rare as an isolated finding of IgG4-RD. Mastoid disease is uncommon and remains a diagnosis of exclusion. Thyroid manifestations pose challenges given unclear diagnostic criteria - Riedel's thyroiditis likely represents IgG4-RD, but the fibrosing variant of Hashimoto's thyroiditis as a form of the so-called 'IgG4-related thyroiditis' requires better characterisation. Eosinophilic angiocentric fibrosis, despite histologic similarities, only partially overlaps with IgG4-RD. This review aims to guide diagnosing IgG4-RD in the head and neck through a systematic, organ-focused discussion of the clinical context, the utility of immunostaining, histological mimics, and controversial issues that pose diagnostic pitfalls. Increased awareness of the nuances and difficulties diagnosing IgG4-RD affecting the head and neck will improve recognition of this protean disease.

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.

Implication of allergy and atopy in IgG4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a chronic multi-organic immune fibrosing disease. It affects preferentially men around middle age and almost any organs can be involved; however, lymph nodes, submandibular and lacrimal glands, pancreas, and retroperitoneum are the most affected. The mainstay treatment is corticosteroids, sometimes adjuncts with DMARDs or rituximab as steroid sparing agents. Th2 inflammation is implicated in the pathophysiology of the disease. Several reports indicate that allergy and/or atopy often affect patients with IgG4-RD. The frequency varies greatly between studies with allergies/allergic diseases reported in 18-76% while atopy is reported in 14-46%. In studies including both, they affect 42 and 62% of patients. Rhinitis and asthma are the most frequent allergic diseases. IgE and blood eosinophiles are often elevated and few studies report that basophils and mast cells could participate in the disease pathogenesis; however, the implication of allergy and atopy remain unclear. No common allergen has been identified and IgG4 production seems to be polyclonal. Although a direct causal effect is unlikely, they could potentially shape the clinical phenotype. Allergies/allergic diseases and/or atopy are reported to be more frequent in IgG4-RD patients presenting head, neck, and thoracic involvement, with higher IgE and eosinophils and less frequent in retroperitoneal fibrosis; however, studies regarding allergy and atopy in IgG4-RD are highly heterogenous. The aim of this article is to review what is currently known about the allergy and atopy in the context of Ig4-RD.

Characteristics of IgG4-related disease complicated with allergic rhinitis or chronic rhinosinusitis: a large cross-sectional cohort study

In clinical practice, we found that IgG4-related disease (IgG4-RD) patients complicated with allergic rhinitis (AR)/chronic rhinosinusitis (CRS) seemed to have unique characteristics different from patients with IgG4-RD alone. In this study, demographic, clinical and laboratory characteristics of IgG4-RD patients complicated with AR/CRS were investigated. We retrospectively analyzed 756 IgG4-RD patients who were recruited in four medical centers from 2009 to 2021. We divided 756 IgG4-RD patients into 2 groups: the case group included IgG4-RD patients complicated with AR/CRS, and the control group included IgG4-RD patients without AR/CRS. 411 patients were complicated with AR/CRS among 756 IgG4-RD patients. Multiple organs involvement (≥ 3, p < 0.0001, OR 3.585 (95% CI 2.655–4.839)) and other types of allergic disease (p < 0.0001, OR 2.007 (95% CI 1.490–2.693)) were more common in the case group. Patients in the case group had a higher level of serum IgG4 (650 mg/dL vs 385 mg/dL, p < 0.0001), IgE (347 mg/dL vs 98 mg/dL, p < 0.0001) and ESR (14 mm/h vs 12 mm/h, p < 0.05). High IgE level (p < 0.01, OR 1.003 (95% CI 1.001–1.005)) and other types of allergic disease (p < 0.05, OR 3.196 (95% CI 1.146–8.908)) were risk factors for patients in the case group, in which most patients had nasal manifestations before the diagnosis of IgG4-RD. The median time interval from nasal symptoms appearance to IgG4-RD diagnosis was − 120 and − 90 months for patients complicated with AR and CRS, respectively. IgG4-RD patients are often complicated with AR/CRS and have distinct characteristics, which appear to be a subgroup of IgG4-RD. The data suggests a pathogenic association of IgG4-RD and AR/CRS.

Immunoglobulin G4-related disease presenting with hypertrophy and sclerosis of the inferior turbinate

Immunoglobulin G4-related disease (IgG4-RD) is a novel clinical disease entity characterized by elevated serum IgG4 concentration and tumefaction or tissue infiltration by IgG4+ plasma cells.1 We report the case of a 56-year-old man who presented with nasal obstruction for 5 years. Rhinoscopy revealed hypertrophy and sclerosis of the inferior turbinate, whereas computed tomography revealed inflammation of the anterior ethmoid sinus and frontal sinuses. An endoscopic inferior turbinectomy was performed, and IgG4-RD was definitively diagnosed based on the histopathological features of the turbinate tissue. Prednisolone was administered postoperatively. IgG4-RD presenting with hypertrophy and sclerosis of the inferior turbinate is rare. Awareness of IgG4-RD originating in the sinonasal cavity is essential to avoid delayed diagnosis.

IgG4-related pachymeningitis masquerading as foramen magnum meningioma: illustrative case

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated inflammatory condition with potential multiorgan involvement. Common manifestations include autoimmune pancreatitis and retroperitoneal fibrosis. Pathological analysis reveals lymphoplasmacytic infiltrate rich in IgG4-positive cells and characteristic storiform fibrosis. Early treatment with glucocorticoids may prevent progression to poorly responsive fibrotic disease.

OBSERVATIONS

A 63-year-old female patient presented with reports of left-sided headaches, nausea, and photophobia in addition to recently diagnosed chronic rhinosinusitis (CRS). Neurological examination revealed dysarthria secondary to left hypoglossal nerve palsy. Computed tomography (CT) revealed a contrast-enhancing extraaxial mass at the left craniocervical junction, CRS with secondary hyperostotic reaction, and multiple hypodense lesions involving the occipital bone. Magnetic resonance imaging revealed a dural-based lesion involving the foramen magnum and invading the left hypoglossal canal. The patient underwent a far-lateral craniotomy. Histopathological analysis revealed severe lymphoplasmacytic inflammation, storiform fibrosis and rich plasma-cell population positive for IgG4. Serum IgG4 was markedly elevated. Total-body CT showed no systemic involvement. The patient was diagnosed with IgG4-RD and was prescribed prednisone, with normalization of her IgG4 levels after 1 month.

LESSONS

IgG4-RD may mimic a variety of diseases, including skull-base meningiomas and CRS. Accurate diagnosis and expedited administration of steroids may prevent unnecessary interventions and progression to treatment-resistant fibrosis.

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.

IgG4 related lung disease- a rare and novel mimic of malignancy and infections-a case series of three patients with a brief review of updated literature

IgG4-related lung disease is an extremely rare and novel entity which is still poorly understood. We reviewed the 16 patients diagnosed with IgG4-related disease from October 2014 through December 2019 at our institution. The three cases that showed pulmonary involvement are included in this series. Of these, two patients had cavitary lung disease and developed aspergilloma and chronic cavitating aspergillosis after a prolonged course of steroid therapy, and one had isolated pulmonary nodule and ground glass opacity. We reviewed the updated literature and briefly described disease epidemiology, clinical characteristics, diagnostic approaches, and management strategies for IgG4-related lung disease.

The neurology of IGG4-related disease

PURPOSE OF REVIEW

IgG4-related disease (IgG4-RD) is emerging as a fibro-inflammatory entity affecting multiple organs, including manifold neurologic manifestations. This review discusses general characteristics of IgG4-RD neurologic disease including epidemiology, histology, clinical picture and treatment approaches.

RECENT FINDINGS

IgG4-RD is increasingly recognized as an important underlying pathophysiology in multiple disorders of neurologic interest, including orbital inflammation, infundibulo-hypophysitis, hypertrophic pachymeningitis, and even in rare cases CNS parenchymal disease and cranial vascular involvement. These were previously considered idiopathic and unrelated to any systemic disease but now known to share a common histopathology. New knowledge regarding the pathogenesis, clinical features and epidemiology of IgG4 is emerging, and new neurological manifestations continue to be described. Diagnostic progress includes CT-PET imaging, the use of flow cytometry for plasmablast quantification, and the use of reverse passive latex agglutination aiming to overcome the prozone phenomenon. Histopathologic confirmation of IgG4-RD remains the gold standard method of diagnosis but new diagnostic criteria for systemic and organ-specific disease are being proposed. Though glucorticoids remain the mainstay of therapy, relapses and incomplete recovery are frequent. Rituximab is a promising treatment in IgG4-RD that is severe, refractory or glucocorticoid dependent. Initiation of immunosuppression at an early stage of disease should be considered in order to avoid development of refractory fibrosis.

SUMMARY

The current review emphasizes the neurologic manifestations of IgG4-RD.

Identifying clinical subgroups in IgG4-related disease patients using cluster analysis and IgG4-RD composite score

Background

To explore the clinical patterns of patients with IgG4-related disease (IgG4-RD) based on laboratory tests and the number of organs involved.

Methods

Twenty-two baseline variables were obtained from 154 patients with IgG4-RD. Based on principal component analysis (PCA), patients with IgG4-RD were classified into different subgroups using cluster analysis. Additionally, IgG4-RD composite score (IgG4-RD CS) as a comprehensive score was calculated for each patient by principal component evaluation. Multiple linear regression was used to establish the “IgG4-RD CS” prediction model for the comprehensive assessment of IgG4-RD. To evaluate the value of the IgG4-RD CS in the assessment of disease severity, patients in different IgG4-RD CS groups and in different IgG4-RD responder index (RI) groups were compared.

Results

PCA indicated that the 22 baseline variables of IgG4-RD patients mainly consisted of inflammation, high serum IgG4, multi-organ involvement, and allergy-related phenotypes. Cluster analysis classified patients into three groups: cluster 1, inflammation and immunoglobulin-dominant group; cluster 2, internal organs-dominant group; and cluster 3, inflammation and immunoglobulin-low with superficial organs-dominant group. Moreover, there were significant differences in serum and clinical characteristics among subgroups based on the CS and RI scores. IgG4-RD CS had a similar ability to assess disease severity as RI. The “IgG4-RD CS” prediction model was established using four independent variables including lymphocyte count, eosinophil count, IgG levels, and the total number of involved organs.

Conclusion

Our study indicated that newly diagnosed IgG4-RD patients could be divided into three subgroups. We also showed that the IgG4-RD CS had the potential to be complementary to the RI score, which can help assess disease severity.

Clinical significance of IgG4 in sinonasal and skull base inflammatory pseudotumor

INTRODUCTION

Inflammatory pseudotumor (IPT) in the sinonasal cavity and skull base region is benign non-neoplastic inflammatory process. However, IPT can mimic malignant tumor or infectious disease and there are difficulties in confirmation of diagnosis. The aim of study is to evaluate the clinical significance of immunoglobulin G4 (IgG4) in IPT in terms of steroid response and differential diagnosis with other skull base infiltrative lesions.

METHODS

Medical records were reviewed retrospectively from 1998 to 2016. Subjects diagnosed with IPT by surgical biopsy were enrolled. IgG4 positivity was defined as IgG4/IgG ratio > 0.4. Additionally, IgG4/IgG ratio was calculated in eight skull base osteomyelitis (SBO) patients.

RESULTS

Twenty-six IPT patients were included and the average age was 52.3 years, and 57.7% were male and 42.3% were female. Most lesions were involved in the sinuses (88.5%) and the incidence of extension beyond the sinuses itself was as follows: the cheek/hard palate/parapharynx (15.4%), orbit (61.5%), skull base (57.7%), and dura or brain (23.1%). All IPT cases revealed IgG4 + plasma cells and IgG4/IgG ratio over 0.4 was detected in 42.3% (11/26) of cases. In case of SBO, no patients had IgG4/IgG ratio exceed 0.4. Main treatment modality was systemic steroids (61.5%) and other modalities were used: surgery (3.8%), immunosuppressant (7.7%), radiotherapy (30.8%), or a combination of these modalities (15.4%). Steroid responses were not significantly different, but IgG4-positive group tended to have better response to steroid therapy.

CONCLUSIONS

IgG4-positive and IgG4-negative IPT patients revealed no differences in involvement sites, clinical course, and steroid responses. However, IgG4/IgG ratio and IgG4 + plasma cell count can provide a diagnostic clue for infiltrative skull base lesions such as IPT and a differential diagnosis of SBO.