An update on IgG4-related lung disease

CT Chest findings in IgG4-related disease

PURPOSE

To investigate the multi-slice spiral Computed Tomography(MSCT) findings of chest involvement in IgG4-related diseases and to improve doctors' understanding of this disease.

MATERIALS AND METHODS

We retrospectively analyzed the clinical and imaging data of 67 patients with clinically confirmed or suspected IgG4-related diseases.

RESULTS

Sixty patients (89.60%) had abnormal chest CT findings. Among them, 47 patients (70.10%) had enlarged mediastinal lymph nodes. Thickening of the tracheal and tracheobronchial perivascular walls was observed in 35 patients (52.20%). Nodules were observed in 29 patients (43.30%). Patches or ground-glass opacities were observed in 15 cases (22.40%); bilateral enlarged axillary lymph nodes, 9 (13.40%); bilateral enlarged hilar lymph nodes, 3 (4.50%); and, interstitial changes, 3 (11.90%). Pleural and pericardial effusion occurred in five cases (7.46%, two bilateral and three unilateral) and three cases (4.50%), respectively. Seven (10.45%) patients showed no obvious abnormalities. The abnormally elevated IgG4 level (>135 mg/dL) was positively correlated with thickening of the tracheal and tracheobronchial walls (r = 0.328, p = 0.007) and enlargement of mediastinal lymph nodes (r = -0.252, p = 0.039), and the logistic regression model 1 showed that the incidence of lung as the first symptom was higher in patients with bilateral enlarged hilar lymph nodes on chest images.

CONCLUSION

Chest CT is of great significance for the diagnosis and follow-up of IgG4-RLD. Chest CT scans should be suggested to be performed when ocular symptoms, bilateral enlarged hilar lymph nodes, pancreatitis, pituitary adenitis, Takayasu arteritis, or abnormally elevated IgG4 levels (>135 mg/dL) are present, and IgG4-RLD should be considered.

Unveiling the immune and vitamin profiles of blood: the potential biomarkers for alopecia areata

Background

Alopecia areata is a hair follicle disorder characterized by the development of multiple circular bald patches on the scalp, often accompanied by elevated cytokine production and immune cell infiltration around hair follicles. Our aspiration is to explore whether blood analysis can reveal additional factors that contribute to the disparities between individuals with alopecia areata and those who are healthy. Such research could potentially establish a robust foundation for the advancement of future therapeutic strategies.

Methods

In Fujian, China, we have collected blood samples from a cohort of 28 alopecia areata patients and a control group of 28 healthy individuals for comparative analysis. A detailed assessment of cytokines, eosinophil counts, vitamin levels, and immunoglobulin profiles within these samples was conducted. Subsequently, statistical analysis was applied to elucidate the differences between the two groups.

Results

While the blood analysis revealed higher average levels of IL-4, IL-10, and TNF-α in alopecia areata patients compared to healthy individuals, these differences were not statistically significant. Similarly, vitamin levels showed no significant variation between the patient and healthy groups. However, the Wilcoxon rank sum test identified a significant increase in IFN-γ and a significant decrease in immunoglobulin IgG4 levels among alopecia areata patients, pointing to a possible role in the disease's pathogenesis. Receiver operating characteristic (ROC) curve analysis had demonstrated that the area under the ROC curve (AUC) for IFN-γ and IgG4 was 0.656 and 0.704, respectively, suggesting that IFN-γ and IgG4 had a certain discrimination effect on alopecia areata. Utilizing the Youden index to optimize specificity, we propose that IgG4 levels below 824.85 mg/L and IFN-γ levels above 0.565 pg/mL could serve as biomarkers for assessing the risk of alopecia areata.

Conclusions

These findings highlight the need for further exploration of the link among alopecia areata, IgG4- and IFN-γ-related mechanisms, potentially uncovering novel therapeutic targets for managing this condition.

Immunoglobulin G4-related disease with pleural involvement in an 80-year-old female patient: A case report and literature review

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD), a rare immune-mediated disease affecting multiple organs, rarely involves the pleura. This study presents a case of pleural IgG4-RD and reviews the literature to elucidate the patient population, manifestations, and diagnostic and treatment characteristics of pleural IgG4-RD. This study aimed to expand the existing case database of pleural IgG4-RD and enhance the understanding and management of this rare disease.

METHODS

We report a case of IgG4-RD involving the pleura in an 80-year-old woman with a weight of 62 kg and a body mass index (BMI) of 23.2 kg/m2. Additionally, we reviewed pleural biopsy-confirmed IgG4-RD cases in the PubMed, Scopus, Web of Science, Embase, and Science Direct databases.

RESULTS

Forty-one patients with IgG4-RD confirmed by pleural biopsy were included. The median age was 69 years, with male predominance (31, 75.6 %). The most common manifestations were pleural effusion (37, 90.2 %) and dyspnea (26, 63.4 %). Elevated serum IgG4 levels were observed in 38 patients (92.7 %), with a median value of 398.2 mg/dL. Twenty-six patients met two histological criteria for IgG4-RD. Thirty-seven patients received glucocorticoid therapy, 34 of whom achieved clinical improvement.

CONCLUSIONS

IgG4-RD with pleural involvement mainly manifests as pleural effusion and dyspnea, responding to glucocorticoid therapy. The possibility of this disease should be considered in patients with pleural effusion and enlargement of tissues or organs. Medical staff should attach importance to the application of the Comprehensive Geriatric Assessment (CGA) and the Geriatric Interdisciplinary Team (GIT) in the disease management of older patients.

Clinical and Imaging Pulmonary Manifestations in IgG4-Related Disease

OBJECTIVES

The aims of this study were to describe the frequency of pleuropulmonary computed tomography (CT) findings in patients with IgG4-related disease (IgG4-RD) and to compare clinical and laboratory characteristics between patients with and without pleuropulmonary involvement in chest CT.

METHODS

This is a study conducted within the IgG4-RD study group of the Argentine Society of Rheumatology (GESAR IgG4) cohort of patients with IgG4-RD. Member centers of the group were requested to submit pulmonary CT scans of the patients. Lung lesions were classified into 4 subtypes: (1) nodules, (2) ground-glass opacity, (3) interstitial-alveolar involvement, and (4) bronchovascular involvement. The presence of pleural involvement and mediastinal adenopathy was also assessed.

RESULTS

We examined data from 28 patients, with 17 (61%) showing pulmonary involvement. The subtypes of pulmonary involvement, in order of frequency, were as follows: type 4 (n = 17, 100%), type 3 (n = 10, 59%), type 2 (n = 6, 36%), and type 1 (n = 5, 29%). Pleural lesions were observed in 2 (12%) cases, and mediastinal adenopathies were found in 4 (23%) cases. No demographic, clinical, or laboratory differences were noted between patients with and without pulmonary involvement, except for serum levels of IgG4, which were higher among patients without pulmonary involvement (339.0 [293.1-1592.1 mg/dL] vs 2869 [1156.3-4037.4 mg/dL]; p = 0.022).

CONCLUSIONS

In this case series, the predominant subtype of pulmonary involvement was septal thickening and increased bronchovascular tissue. Patients with and without pleuropulmonary involvement exhibited similar clinical and laboratory manifestations, except for serum IgG4, which was higher in patients without pleuropulmonary involvement.

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.

A case with multiple nodules and mucosal oedema of the trachea and both bronchi induced by IgG4-related disease

BACKGROUND

IgG4-related disease is a systemic fibroinflammatory disease that is mainly seen in older men, and involves multiple organs, such as the pancreas and lungs. However, 75% of patients with IgG4-related lung disease are asymptomatic (if they are symptomatic, they mainly complain of nasal congestion, rhinorrhoea, chest pain, and cough) and are incidentally diagnosed through chest computed tomograph. Although, nodules in the airway and bronchial wall thickening are criteria for diagnosis, it is important that nodules have been reported in peripheral airways in several cases and rarely in the central airway.

CASE PRESENTATION

A 74-year-old woman previously diagnosed with Mikulicz's disease presented with swelling of the eyelid margin on both sides and visual disturbances. Computed tomography revealed extensive multiple nodules and mucosal oedema of the trachea and both bronchi. On flexible bronchoscopy under local anaesthesia, extensive lesions were observed from the middle of the trachea to the carina, extending into both segmental bronchi. The nodules were continuous with the normal respiratory tract mucosa, and the surfaces were smooth with minimal neovascularisation. Due to the solid nature of the lesion, obtaining an adequate amount of specimen was challenging. Therefore, we used a 1.9 mm cryoprobe under intubation, resulting in minimal bleeding. Subsequently, the patient was diagnosed with IgG4-related lung disease.

CONCLUSIONS

The present case is very rare because of the presence of multiple nodules, severe mucosal edema of the central airway and the absence of mediastinal lymphadenopathy, ground glass nodules, and lung masses. Therefore, it is important to consider differential diagnoses. Thus, we emphasise the importance of endobronchial cryobiopsy for obtaining an adequate number of tissue specimens in such cases to establish a definitive pathological diagnosis.

Immunoglobulin G4-Related Lung Disease with Waxing and Waning Pulmonary Infiltrates: A Case Report

Immunoglobulin G4 (IgG4)-related lung disease can have various clinical courses. To our knowledge, reports of IgG4-related lung disease with waxing and waning pulmonary infiltrates only are very rare. A few lung nodules and ground glass opacities were incidentally found in a pre-operative evaluation in a 36-year-old female. The lung lesions showed waxing and waning in the follow-up chest CT. She underwent a surgical biopsy, and IgG4-related lung disease was confirmed.

[IgG4-related disease: A proteiform pathology with frequent chest manifestations]

INTRODUCTION

While IgG4-related disease (IgG4-RD) was initially described in the early 2000s, its polymorphic clinical manifestations were previously reported under different names ; they have in common the presence of IgG4+ oligoclonal plasma cells and fibrosis.

STATE OF THE ART

Ruling out certain differential diagnoses, the diagnosis of IgG4-RD is based on a bundle of clinical, biological and histological features. Chest involvement is variable and can affect the mediastinum, bronchi, parenchyma, pleura and/or, more rarely, bones and (pericardium, aorta, coronary…) vascular structures. The most frequent radiological manifestations are peribronchovascular thickening, mediastinal lymphadenopathy, and nodular or interstitial patterns. Pleural involvement and posterior mediastinal fibrosis are less frequent, while thoracic paravertebral tissue thickening is highly specific. Systemic corticosteroids are the cornerstone of treatment. In case of relapse or as frontline therapy in case of risk factors for relapse and/or poor tolerance of corticosteroids), a steroid-sparing agent (most often rituximab) is added, and biannual maintenance infusions are associated with a lower risk of relapse.

PERSPECTIVES

An international consensus has recently led to the development of classification criteria that should standardize the diagnostic approach and homogenize the enrolment of patients in epidemiological as well as therapeutic studies. Other treatments are also under evaluation, including biologics targeting T2 inflammation, CD-19 (inebilizumab, obexelimab), SLAMF7 (elotuzumab) surface proteins, Bruton's tyrosine kinase, and the JAK/STAT pathway.

CONCLUSIONS

Substantial progress has been made over recent years in understanding IgG4-RD pathophysiology, and personalized patient care seems to be an achievable medium-term goal.

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 report of hepatic angiomyolipoma, inflammatory subtype. Clinico-pathological characterization: a diagnostic challenge

BACKGROUND

Angiomyolipoma is a benign mesenchymal neoplasm of a wide histological heterogeneity belonging to the PEComa "family." The liver, after the kidney, is their second most frequent location. However, inflammatory hepatic AMLs constitute a rare entity, with only fourteen documented cases until 2020. These neoplasms can overlap morphological features of IgG4-related diseases, being of great diagnostic relevance to demonstrating myomelanocytic-lineage differentiation of the neoplastic cells.

CASE PRESENTATION

we present a new case of an inflammatory hepatic AML resembling an IgG4-related disease in a 35-year-old woman with a subcapsular 5 cm mass confined to segment VII of the right hepatic lobe. Although having reduced its size along the tumor's natural evolution, complete tumor resection was decided due to its hypermetabolic behavior (max. SUV = 12,6) assessed by PET-CT scan. Finally, the patient underwent a right hepatectomy due to spontaneous rupture and bleeding of the lesion during the intervention. All the diagnostic and therapeutic procedures occurred in the last months of the COVID-19 pandemic.

CONCLUSIONS

This review aims to describe inflammatory hepatic AML histological and immunohistochemical features. We further sought to establish a clinicopathological contextualization of this tumoral subtype.

Lung and Pleural Immunoglobulin G4-Related Disease: Two Contrasting Case Reports

Immunoglobulin G4-related disease (IgG4-RD) is an immunomediated disease that can virtually affect any organ. Despite the pancreas being known as the most frequently involved organ, pulmonary and pleural IgG4-RD is being increasingly reported. The authors present two cases of IgG4-RD diagnosed in the same year, with different presentations and outcomes, in which the lung and pleural involvement were essential for the diagnosis. Recognizing IgG4-RD as a possible cause of chronic pleural effusion and/or thickening and lung abnormalities is important for an early diagnosis and prognosis improvement.

Thoracic manifestations of IgG4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a recently described rare systemic fibroinflammatory disease with an estimated incidence of less than 1 in 100,000 persons per year. The disease can affect virtually any organ and is characterized by unifying histopathological findings. Recently, four subgroups of patients have been characterized: hepatobiliary, head and neck, Mikulicz syndrome and retroperitoneal fibrosis, who illustrate the mainly abdominal and ENT tropism of the disease. Yet, thoracic involvement is not uncommon. It can be detected in up to 30% of patients with systemic IgG4-RD and is the exclusive manifestation of the disease in about 10% of cases. Clinical symptoms are nonspecific and may include dyspnoea, cough or chest pain. Chest CT findings are heterogeneous and primarily include peribronchovascular thickening, nodules, ground-glass opacities and lymphadenopathy. There is no specific diagnostic test for IgG4-RD thoracic involvement, which may mimic malignancy or vasculitis. Therefore, a cautious approach is needed to make an accurate diagnosis: a search for extra-thoracic manifestations, elevated serum IgG4 levels, circulating levels of plasmablasts and pathologic evidence of disease is warranted. Although very suggestive, neither the presence of a polyclonal IgG4 lymphoplasmacytic infiltrate, storiform fibrosis or obliterative phlebitis are sufficient to confirm the histological diagnosis. Steroids are recommended as first-line therapy. Rituximab or disease-modifying antirheumatic drugs may be used in relapsed or rare cases of steroid-refractory disease. In this review, we summarize current knowledge regarding the pathophysiology, epidemiology, diagnostic modalities (clinical-biological-imaging-histopathology) and treatment of IgG4-RD thoracic involvement.

Immunoglobulin G4-Related Lung Disease Mimicking Lung Cancer: Two Case Reports

Immunoglobulin G4 (IgG4)-related disease is a rare systemic fibroinflammatory condition characterized by elevated serum IgG4 levels and infiltration of IgG4-positive plasma cells in various organs. IgG4-related lung disease shows varied radiologic features on chest CT. Patients usually present with a solid nodule or mass mimicking lung cancer; therefore, distinguishing between IgG4-related disease and other conditions is often challenging. Additionally, co-existing radiologic findings of IgG4-related lung disease may mimic metastasis or lymphangitic carcinomatosis of the lung. We report two cases of histopathologically confirmed IgG4-related lung disease mimicking lung cancer. Chest CT revealed a solid nodule or mass with ancillary radiologic findings, which suggested lung cancer; therefore, IgG4-related lung disease was radiologically indistinguishable from lung cancer in both cases. Measurement of serum IgG4 levels and clinical evaluation to confirm involvement of various organs may be useful to establish the differential diagnosis. However, surgical biopsy evaluation is needed for confirmation.

Severe asthma as the initial clinical manifestation of IgG4-related disease: a retrospective clinical study

Background

Respiratory involvement is common in immunoglobulin G4-related disease (IgG4-RD). However, severe asthma as the initial clinical manifestation of IgG4-RD is rare and might be neglected by respiratory clinicians. We aimed to explore the clinical characteristics and prognoses of patients with immunoglobulin G4-related disease (IgG4-RD) manifesting as severe asthma.

Methods

A retrospective analysis of the clinical characteristics and prognoses of patients with severe asthma who were eventually diagnosed with IgG4-RD was performed in the Peking Union Medical College Hospital from 2013 to 2019.

Results

Twelve patients (5males, 7 females) were included. The mean age at enrollment and age of asthma onset were 59.4 ± 10.1 and 53.8 ± 10.4 years, respectively. The mean duration of asthma symptoms was 5.7 ± 2.0 years. In all patients, the proportion (25.1 ± 10.3%) and count (2.0 ± 1.1) × 10⁹/L of eosinophils in peripheral blood increased. Additionally, all patients exhibited elevated total immunoglobulin E [IgE, (1279.3 ± 1257.9) KU/L] and IgG4 (9155.8 ± 9247.6) mg/dL. Bronchial wall thickening (n = 11) and mediastinal/hilar lymphadenopathy (n = 11) were major chest CT manifestations. All were pathologically diagnosed through surgical biopsy; submandibular gland (n = 8), supraclavicular lymph node (n = 2), stomach (n = 1), rashes (n = 1), lacrimal gland (n = 1) and thoracoscopic lung (n = 1) biopsies were performed. Asthma was well controlled by oral glucocorticoids (GCs), but some patients relapsed during tapering (n = 11). The refractory condition was controlled after increasing the dosage of GCs and add-on immunosuppressants.

Conclusions

For patients with middle age-onset severe asthma with elevated eosinophils, total IgE and IgG4 levels and available salivary gland ultrasound imaging, ruling out IgG4-RD is recommended. GCs used in combination with immunosuppressants is recommended to prevent relapse.

Update on classification, diagnosis, and management of immunoglobulin G4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a newly recognized chronic fibro-inflammatory autoimmune disease, and its recognition has been constantly increasing worldwide over the last few years. A correct and timely recognition, as well as appropriate intervention, is crucial for the treatment of IgG4-RD. For certain subtypes of IgG4-RD, organ-specific criteria are formulated to make the diagnosis more accurate. New biomarkers have emerged in the recent years to aid the disease diagnosis, its prognosis prediction, as well as therapy response monitoring. Although recurrence is very common in IgG4-RD, glucocorticoid is still the first-line treatment for the majority of patients. The factors that affect the likelihood of disease relapse are multifaceted. The selection strategy of various steroid-sparing agents is still being explored. Besides, when patients have special sites involvement leading to severe clinical conditions, surgical operation or interventional therapy should also be considered. An update on classification, diagnosis, and management of IgG4-RD is provided in the current study to fully elucidate the recommended clinical practice of this mysterious disease.

Thoracic involvement and imaging patterns in IgG4-related disease

OBJECTIVE

Immunoglobulin G4-related disease (IgG4-RD) is a rare orphan disease. Lung, pleura, pericardium, mediastinum, aorta and lymph node involvement has been reported with variable frequency and mostly in Asian studies. The objective of this study was to describe thoracic involvement assessed by high-resolution thoracic computed tomography (CT) in Caucasian patients with IgG4-RD.

METHODS

Thoracic CT scans before treatment were retrospectively collected through the French case registry of IgG4-RD and a single tertiary referral centre. CT scans were reviewed by two experts in thoracic imagery blinded from clinical data.

RESULTS

48 IgG4-RD patients with thoracic involvement were analysed. All had American College of Rheumatology/European League Against Rheumatism classification scores ≥20 and comprehensive diagnostic criteria for IgG4-RD. CT scan findings showed heterogeneous lesions. Seven patterns were observed: peribronchovascular involvement (56%), lymph node enlargement (31%), nodular disease (25%), interstitial disease (25%), ground-glass opacities (10%), pleural disease (8%) and retromediastinal fibrosis (4%). In 37% of cases two or more patterns were associated. Asthma was significantly associated with peribronchovascular involvement (p=0.04). Among eight patients evaluated by CT scan before and after treatments, only two patients with interstitial disease displayed no improvement.

CONCLUSION

Thoracic involvement of IgG4-RD is heterogeneous and likely underestimated. The main thoracic CT scan patterns are peribronchovascular thickening and thoracic lymph nodes.

Curcumin deactivates M2 macrophages to alleviate lung fibrosis in IgG4-related disease through activating the toll-like receptor 9 pathway

OBJECTIVES

To explore the effects and mechanism of Curcumin on pulmonary fibrosis in IgG4-related disease (IgG4-RD).

METHODS

The expression of fibrosis factors, inflammatory factors and markers of M1/M2 macrophages in lung tissue of IgG4-RD patients was detected by RT-qPCR or Western blotting. The macrophages of IgG4-RD patients were isolated and treated with different concentrations of Curcumin, and the markers of M1/M2 macrophages were detected by RT-qPCR, Western blotting or ELISA. Next, the pulmonary fibroblasts of IgG4-RD patients were isolated and cultured with the supernatant of macrophages treated with Curcumin. Cell proliferation and migration were detected by CCK-8 and Transwell assay, respectively. SOD activity and ROS content were detected by the xanthine oxidase method and flow cytometry, respectively. Then the expression of Toll-like Receptor 9 (TLR9) and its downstream proteins were detected by Western blotting. After treating the cells with TLR9 antagonist IRS869, the changes in the above indicators were further detected.

RESULTS

The collagen deposition, inflammatory factors secretion and M2 polarization of macrophages were increased in lung tissue of IgG4-RD patients. Curcumin decreased the macrophage M2 polarization and inhibited the proliferation and migration of fibroblasts, reduced the level of oxidative stress, and suppressed the occurrence of fibrosis. The TLR9 pathway was inhibited in IgG4-RD lung tissues, and Curcumin activated this pathway and reduced macrophage M2 polarization. And the inhibitory effect of Curcumin on pulmonary fibrosis could be reversed by IRS869.

CONCLUSIONS

Curcumin inhibited the occurrence of pulmonary fibrosis in IgG4-RD by inhibiting the TLR9 signaling pathway-mediated macrophage M2 polarization.

Immune Dysregulation in IgG4-Related Disease

Immunoglobin G₄-related disease (IgG₄-RD) is one of the newly discovered autoimmune diseases characterized by elevated serum IgG₄ concentrations and multi-organ fibrosis. Despite considerable research and recent advances in the identification of underlying immunological processes, the etiology of this disease is still not clear. Adaptive immune cells, including different types of T and B cells, and cytokines secreted by these cells play a vital role in the pathogenesis of IgG₄-RD. Antigen-presenting cells are stimulated by pathogens and, thus, contribute to the activation of naïve T cells and differentiation of different T cell subtypes, including helper T cells (Th1 and Th2), regulatory T cells, and T follicular helper cells. B cells are activated and transformed to plasma cells by T cell-secreted cytokines. Moreover, macrophages, and some important factors (TGF-β, etc.) promote target organ fibrosis. Understanding the role of these cells and cytokines implicated in the pathogenesis of IgG₄-RD will aid in developing strategies for future disease treatment and drug development. Here, we review the most recent insights on IgG₄-RD, focusing on immune dysregulation involved in the pathogenesis of this autoimmune condition.

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.

[IgG4-Related Disease: A rare cause of severe interstitial lung disease]

BACKGROUND

The intrathoracic manifestations of IgG4-related disease include a range of conditions and severity, and can on occasion cause acute respiratory failure as reported in the case described here.

OBSERVATION

A 69-year-old male former smoker, was admitted to our hospital with dyspnea, fever, cough, fatigue, and a 3-month history of weight loss. He received high flow oxygen therapy and non-invasive ventilation for severe respiratory failure. Chest computed tomography revealed multifocal condensations and ground glass opacities, accompanied by thickening of the perilymphatic interstitium, mediastinal lymphadenopathy and bilateral pleural effusion. Elevated serum concentrations of IgG4 suggested an IgG4-Related Disease. He developed renal failure and underwent a renal biopsy. Histopathological analysis of which supported the diagnosis by showing dense lymphocytic infiltrate with a count of IgG4+ cells/hpf higher than 60, and storiform fibrosis - a swirling, "cartwheel" pattern of fibrosis which may have a patchy distribution. The patient responded well to steroid therapy.

CONCLUSION

Although respiratory symptoms are usually mild in IgG4-relatd disease, thoracic features can evolve into acute respiratory failure with few extra thoracic manifestations.

IgG4-related nephritis and interstitial pulmonary disease complicated by invasive pulmonary fungal infection: a case report

Background

IgG4-related kidney disease (IgG4-RKD) can affect multiple organs, which was first reported as a complication or extra-organ manifestation of autoimmune pancreatitis in 2004. It is characterized by abundant IgG4-positive plasma cells infiltration in tissues involved.

Case presentation

A 69-year-old man presented with cough and renal dysfunction with medical history of hypertension and diabetes. Pathological findings revealed interstitial nephritis and he was initially diagnosed with IgG4-RKD. Prednisone helped the patient to get a remission of cough and an obvious decrease of IgG4 level. However, he developed invasive pulmonary fungal infection while steroid theatment. Anti-fungal therapy was initiated after lung puncture (around cavitary lung lesion). Hemodialysis had been conducted because of renal failure and he got rid of it 2 months later. Methylprednisolone was decreased to 8 mg/day for maintenance therapy. Anti-fungal infection continued for 4 months after discharge home. On the 4th month of follow-up, Chest CT revealed no progression of lung lesions.

Conclusions

The corticosteroids are the first-line therapy of IgG4-RD and a rapid response helps to confirm the diagnosis. This case should inspire clinicians to identify IgG4-related lung disease and secondary pulmonary infection, pay attention to the complications during immunosuppressive therapy for primary disease control.

Plasma cell-rich bronchoalveolar lavage fluid: Could be a first clue to IgG4 plasma cell-related lung disease

Plasma cells are usually absent in normal bronchoalveolar lavage (BAL) fluids. Frequent plasma cells in BAL are always pathologically significant. They raise a rather narrow differential diagnosis, predominantly extrinsic allergic alveolitis and few other interstitial lung diseases. BAL is a key diagnostic procedure for certain lung diseases. Because plasma cells are uncommon in BAL fluids and usually associated with limited conditions compared to other more common interstitial lung diseases, the focus of cell count differentials in BAL fluids was on other mononuclear and granulocytic inflammatory cells. Recently, cases of IgG4 positive plasma cell-related lung diseases have been reported in tissue specimens. This may raise the importance of cytologically recognizing plasma cells in BAL fluids. We report a case of a 16-year-old boy with clinical and radiologic features of diffuse interstitial lung disease. His BAL cytology showed frequent plasma cells. Endobronchial biopsy showed substantial infiltration by plasma cells confirmed by immunohistochemistry. After excluding other lung diseases, the possibility of IgG4 plasma cell-related disease was raised. Blood tests showed elevated serum levels of IgG4. This case emphasizes the importance of including of IgG4 plasma cell-related lung disease as a possible differential diagnosis. This should prompt proper serologic tests for confirmation and appropriate management. With increasing reports of IgG4-related lung disease, cytopathologists should be aware of this possibility when examining BAL fluids. Measurement of IgG levels in BAL fluids and plasma cell immunophenotyping might be promising tools.

[IGG4-related diseases in endocrinology]

Immunoglobulin-G4-related disease (IgG4-RD) is a chronic immunomediated pathology of different organs of local or systemic nature, which has been established as a separate clinical entity in the early 2000s and is characterized by storiform fibroid inflammation of the affected tissues, their increase, and elevated serum immunoglobulin-G4 (IgG4) levels. The most common manifestations of the disease are major salivary and lacrimal gland enlargement, lymphadenopathy and type 1 autoimmune pancreatitis (AIP1), however, other organs may be also involved (the thyroid, eyes, meninges, heart, lungs, kidneys, aorta, upper airways, mesentery, etc.). The effectiveness of treatment of IgG4-RD, as well as other pathological conditions, is also determined by the timely diagnosis. However, the latter is complicated due to the variety of clinical manifestations and rather variable diagnostic criteria. It is necessary to constantly update the evidence-based knowledge and diagnostic algorithms within this pathology in order to overcome the difficulties, and involve immunologists, endocrinologists, pathologists and specialists in other spheres. This review provides information about the etiology, pathogenesis, and current methods of diagnosis and treatment of IgG4-related diseases, as well as examples of some manifestations of IgG4-RD that an endocrinologist may face in practice.

Update on IgG4-mediated autoimmune diseases: New insights and new family members

Antibodies of IgG4 subclass are exceptional players of the immune system, as they are considered to be immunologically inert and functionally monovalent, and as such may be part of classical tolerance mechanisms. IgG4 antibodies are found in a range of different diseases, including IgG4-related diseases, allergy, cancer, rheumatoid arthritis, helminth infection and IgG4 autoimmune diseases, where they may be pathogenic or protective. IgG4 autoimmune diseases are an emerging new group of diseases that are characterized by pathogenic, antigen-specific autoantibodies of IgG4 subclass, such as MuSK myasthenia gravis, pemphigus vulgaris and thrombotic thrombocytopenic purpura. The list of IgG4 autoantigens is rapidly growing and to date contains 29 candidate antigens. Interestingly, IgG4 autoimmune diseases are restricted to four distinct organs: 1) the central and peripheral nervous system, 2) the kidney, 3) the skin and mucous membranes and 4) the vascular system and soluble antigens in the blood circulation. The pathogenicity of IgG4 can be validated using our classification system, and is usually excerted by functional blocking of protein-protein interaction.

Mimickers of pulmonary lymphoma

There are multiple entities that involve the lung that have radiographic, clinical, and morphologic overlaps with pulmonary lymphoma. In this review, we will discuss these entities in detail and provide relevant updates.

Pleural, pancreatic and prostatic involvement in IgG4-related disease mimicking pancreatic head malignancy

We describe the case of a gentleman with pleural thickening. On follow-up imaging, dilatation of the main pancreatic and common biliary ducts was noted and an initial diagnosis of pancreatic malignancy was made. During his preoperative workup for pancreatic head malignancy, a PET-CT was performed, which demonstrated increased uptake in the pancreas, in the pleura and in the prostate gland. This raised the possibility of immunoglobulin G4-related disease (IgG4-RD), which was effectively treated with oral steroids. IgG4-RD is a well-described cause of autoimmune pancreatitis but can affect other regions, including the pleura and prostate. It is essential that radiologists are aware of the imaging findings in IgG4-RD and can direct clinicians towards this important multisystem diagnosis.

IgG4-related disease: a clinical perspective

IgG4-related disease (IgG4-RD) is a recently recognized fibro-inflammatory disorder that can affect almost any organ. Common presentations include major salivary and lacrimal gland enlargement, orbital disease, autoimmune pancreatitis, retroperitoneal fibrosis and tubulointerstitial nephritis. The main histopathological features are a dense, polyclonal, lymphoplasmacytic infiltrate rich in IgG4+ plasma cells, storiform fibrosis and obliterative phlebitis. The precise pathogenic mechanisms of IgG4-RD are still unclear. CD4+ T and B cells, including IgG4-expressing plasmablasts, constitute the major inflammatory cell populations and are believed to cause organ damage and tissue fibrosis. The diagnosis of the disease may be challenging and should be based on specific histopathological findings, typical laboratory and radiological aspects and an appropriate clinical context. The first-line treatment of IgG4-RD is based on glucocorticoids, which are usually efficacious. However, B cell depletion induced by rituximab has also been found to induce remission in steroid-resistant disease or has been used as steroid-sparing agent for relapsing disease. This review provides an update on clinical and therapeutic aspects of IgG4-RD.

Long-term efficacy of maintenance therapy with Rituximab for IgG4-related disease

BACKGROUND

IgG4-Related Disease (IgG4-RD) promptly responds to glucocorticoids but relapses in most patients. Rituximab (RTX) represents a promising strategy to avoid IgG4-RD flares but its administration for maintaining disease remission has never been assessed in terms of optimal timing of infusion, dosage, and duration of treatment. In the present study we aimed to evaluate the efficacy and safety of RTX for maintenance of IgG4-RD remission.

METHODS

Fourteen patients with IgG4-RD were treated with RTX as induction of remission therapy at the San Raffaele Scientific Institute in Milan, Italy. The cohort was then divided into two study groups: patients re-treated only in case of disease relapse (Group 1, n = 7), and patients regularly re-treated with RTX every 6 months for maintenance therapy (Group 2, n = 7). Data on free-relapse rate and adverse events were collected and retrospectively analysed.

RESULTS

Median follow-up time and baseline clinical-serological features were similar between Group 1 and 2 (p > 0.05). The free relapse rate 18 months after induction of remission treatment was significantly lower in Group 1 (29%) than in Group 2 (100%) (p = 0.006). Infectious complications developed in 6/14 patients (3 in Group 1 and 3 in Group 2).

CONCLUSION

Administration of RTX every 6 months as maintenance of remission therapy prevents IgG4-RD flares.