IgG4-related pleural disease diagnosed by a re-evaluation of chronic bilateral pleuritis in a patient who experienced occasional acute left bacterial pleuritis

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.

Validation of a diagnostic flowchart for tuberculous pleurisy in pleural fluid with high levels of adenosine deaminase

INTRODUCTION

Adenosine deaminase (ADA) in pleural fluid is a useful marker for diagnosing tuberculous pleurisy. However, recent studies have reported a lower specificity of pleural fluid ADA levels. We previously developed a diagnostic flowchart for patients with pleural fluid ADA ≥40 U/L, incorporating variables such as pleural fluid lactate dehydrogenase <825 U/L, predominant pleural fluid neutrophils or cell degeneration, and a pleural fluid ADA/total protein ratio <14. This flowchart was effective in distinguishing between tuberculous pleurisy and other diseases. Here, we conducted a validation analysis of this flowchart.

MATERIALS AND METHODS

We retrospectively collected data from 458 patients with pleural fluid ADA concentrations ≥40 U/L across eight institutions from January 2019 to December 2023. The diagnostic accuracy rate, sensitivity, and specificity of the diagnostic flowchart were analysed and compared to those in the original study.

RESULTS

Eighty-seven patients were diagnosed with tuberculous pleurisy, and 371 patients were diagnosed with other diseases. The diagnostic accuracy, sensitivity, and specificity for diagnosing tuberculous pleurisy were 77.7%, 86.2%, and 75.7%, respectively. Compared with that in the original study, the rate of tuberculous pleurisy was lower (19.0% vs. 44.5%, p < 0.001), but the diagnostic accuracy rates were not significantly different (p = 0.253). On the basis of the findings from this validation study, we have revised the flowchart to enhance its utility.

CONCLUSION

The diagnostic flowchart exhibited high diagnostic accuracy in this validation study, comparable to that in the original study. This validation confirms the effectiveness of the flowchart, even in settings with a low incidence of tuberculosis.

Diagnostic flowchart for tuberculous pleurisy, pleural infection, and malignant pleural effusion

BACKGROUND

Several markers for the diagnosis of pleural effusion have been reported; however, a comprehensive evaluation using those markers has not been performed. Therefore, this study aimed to develop a diagnostic flowchart for tuberculous pleurisy, pleural infection, malignant pleural effusion, and other diseases by using these markers.

METHODS

We retrospectively collected data from 174 patients with tuberculous pleurisy, 215 patients with pleural infection other than tuberculous pleurisy, 360 patients with malignant pleural effusion, and 209 patients with other diseases at Fukujuji Hospital from January 2012 to October 2022. The diagnostic flowchart for four diseases was developed by using several previously reported markers.

RESULTS

The flowchart was developed by including seven markers: pleural ADA ≥40 IU/L, pleural fluid LDH <825 IU/L, pleural fluid ADA/TP < 14, neutrophil predominance or cell degeneration, peripheral blood WBC ≥9200/μL or serum CRP ≥12 mg/dL, pleural amylase ≥75 U/L, and the presence of pneumothorax according to the algorithm of a decision tree. The accuracy ratio of the flowchart was 71.7 % for the diagnosis of the four diseases, with 79.3 % sensitivity and 75.4 % positive predictive value (PPV) for tuberculosis pleurisy, 75.8 % sensitivity and 83.2 % PPV for pleural infection, 88.6 % sensitivity and 68.8 % PPV for malignant pleural effusion, and 33.0 % sensitivity and 60.0 % PPV for other diseases in the flowchart. The misdiagnosis ratios were 4.6 % for tuberculosis pleurisy, 6.8 % for pleural infection, and 8.3 % for malignant pleural effusion.

CONCLUSION

This study developed a useful diagnostic flowchart for tuberculous pleurisy, pleural infection, malignant pleural effusion, and other diseases.

Metachronous bilateral immunoglobulin G4-related pleuritis: A case report and literature review

Immunoglobulin G4-related disease (IgG4-RD) is a newly recognized disease, and therefore its clinical features are not yet fully understood. Here, we describe a surgical case of metachronous bilateral IgG4-related pleuritis and postoperative chylothorax. This case could provide key insights into the pathology of IgG4-RD from a surgical perspective. We present a 70-year-old woman who had a right pleural mass. Video-assisted thoracoscopic pleural mass resection was performed, and the patient was diagnosed with right-sided IgG4-related pleuritis. Two years later, she was also diagnosed with left-sided IgG4-related pleuritis. We suspected the presence of IgG4-positive plasma cell infiltration. Additionally, she experienced a complicated postoperative chylothorax on the left side. It is important to consider the altered course of lymphatic vessels when extensively removing the pleura near the right thoracic duct. The occurrence of metachronous bilateral IgG4-associated pleuritis has not been previously reported, making this case particularly significant for understanding the pathology of IgG4-RD from a surgical standpoint.

Pleural Involvement in IgG4-Related Disease: Case Report and Review of the Literature

Diagnostic work-up of IgG4-related disease (IgG4-RD) pleural involvement is a complex task, as there is a broad spectrum of differential diagnoses to consider. We report the case of a patient presenting with relapsing pleural effusion, discussing the main challenges for achievement of a definite diagnosis. A 63-year-old man was admitted for pleural effusion prevalent on the ride side, initially labeled as idiopathic non-specific pleuritis, based on tissue evaluation after a medical thoracoscopy. He was started on steroids with initial improvement, but a later CT scan showed a relapse of pleural effusion associated with diffuse pleural thickening; a subsequent surgical pleural biopsy revealed features suggestive for IgG4-RD, with a marked increase of IgG4 positive plasma cells. High IgG4 serum levels were also found. The present case underlines the importance of increasing awareness of this potential condition among physicians in order to properly guide the diagnostic work-up, as it is likely that IgG4-RD accounts for a proportion of patients with pleural effusions, labeled as idiopathic. In particular, in patients with unexplained pleural effusion, IgG4-RD should be included among differential diagnoses when lymphoplasmacytic infiltration is observed, and a multidisciplinary interaction between clinicians and pathologists appears crucial for an accurate diagnosis and an appropriate management.

Refractory IgG4-related Pleural Disease with Chylothorax: A Case Report and Literature Review

We herein report a rare case of a 66-year-old man with refractory chylothorax. Although he had been treated with moderate doses of prednisolone (PSL) on suspicion of pleuritis with Sjögren syndrome, the pleural effusion expanded after the reduction of PSL. Further workup including histopathological examinations of pleura led to the diagnosis of IgG4-RD with bilateral chylothorax without any leakage from the thoracic duct. Combination therapy with high-dose PSL plus rituximab successfully decreased the pleural effusion. This is a very rare case of IgG4-related pleuritis with chylothorax and the first report of its successful treatment with rituximab.

Multiple pleural nodules diagnosed as IgG4-related disease: a case report

BACKGROUND

Immunoglobulin G4 (IgG4)-related diseases are characterized by abnormal IgG4 levels, swelling, and marked infiltration and fibrosis of the lymphocytes and IgG4-positive plasma cells, causing hypertrophic lesions or nodules. The cause is currently not well understood. IgG4-related diseases involving lesions limited to the pleura are extremely rare. Herein, we report an IgG4-related disease presenting with multiple pleural nodules confirmed by thoracoscopic surgical biopsy.

CASE PRESENTATION

A 74 year-old man was referred to our department for definitive diagnosis of multiple pleural nodules after 1 year of follow-up. Computed tomography of the chest revealed multiple pleural nodules, while 2-deoxy-2-( 18F)-fluorodeoxyglucose positron emission tomography imaging exhibited tracer accumulation in the nodules. A thoracoscopic surgical biopsy was performed. Histopathological examination revealed hyalinized fibrous tissue with a high degree of plasma cell-based inflammatory cell infiltration. Immunohistochemically, IgG4-positive cells were conspicuous, accounting for 70.5% of the plasma cells. The postoperative serum IgG4 concentration was 289 mg/dL. We diagnosed the patient with an IgG4-related disease with multiple pleural nodules. The postoperative course was good, and the patient is currently being followed up.

CONCLUSION

IgG4-related disease should be considered in cases presenting with multiple pleural nodules.

IgG4-related pleural effusion with high adenosine deaminase levels: A case report and literature review

RATIONALE

Levels of pleural fluid adenosine deaminase (ADA), a useful marker for the diagnosis of tuberculous pleurisy, are elevated in some reports of immunoglobulin G4 (IgG4)-related pleural effusion. We describe a patient with IgG4-related pleural effusion who exhibited a high concentration of ADA. Furthermore, we reviewed the literature to compare patients with IgG4-related pleural effusion and tuberculous pleurisy.

PATIENT CONCERNS

A 75-year-old male patient had dyspnea for 1 month with a left pleural effusion that was exudative, lymphocyte dominant. The pleural fluid test results revealed a total protein (TP) concentration of 6.60 g/dl, a lactate dehydrogenase (LDH) level of 383 IU/dl, and an ADA concentration of 54.5 U/L. An interferon gamma release assay showed a negative result.

DIAGNOSES

Histological analysis of the thoracoscopic pleural biopsy revealed lymphoplasmacytic infiltration, with 80 IgG4-positive plasma cells/high-power field, and an IgG4/IgG ratio of approximately 40% to 50%. Other diseases were ruled out based on symptoms, negative autoimmune antigen results, and histopathologic findings. Thus, he was diagnosed with IgG4-related pleural effusion.

INTERVENTIONS

He received 15 mg of prednisolone as therapy.

OUTCOMES

His pleural effusion and symptoms improved gradually within several months, and prednisolone was tapered to 6 mg daily.

LESSONS

It is important to distinguish between IgG4-related pleural effusion and tuberculous pleurisy. Therefore, we compared 22 patients with IgG4-related pleural effusion from PubMed and the Japan Medical Abstracts Society to 40 patients with tuberculous pleurisy at Fukujuji Hospital from January 2017 to May 2019. According to thoracentesis findings, 14 of 18 patients with IgG4-related pleural effusion had high ADA more than 40 U/L. The pleural effusion of patients with IgG4-related pleural effusion showed higher TP levels (P < .001) and lower LDH (P < .001) and ADA levels (P = .002) than those with tuberculous pleurisy. Moreover, the pleural fluid ADA/TP ratio was a good predictor for differentiating IgG4-related pleural effusion and tuberculous pleurisy (area under the receiver operating characteristic curve of 0.909; 95% confidence level: 0.824-0.994).

Pleural effusion related to IgG4

Purpose of review

The causes of exudative pleural effusions are diverse and frequently remain unclear despite exhaustive examinations. Recently recognized IgG4-related disease (IgG4-RD) is a fibroinflammatory disorder that can affect nearly any organ including the lungs. This review will focus on the involvement of IgG4 in exudative pleural effusion of unknown cause.

Recent findings

IgG4 is found to be involved in a proportion of patients with undiagnosed pleural effusions. Pleural involvement in IgG4-RD can be seen in isolation or association with other organ disease. Pleural thickening and/or effusion are common clinical features of IgG4-related pleural lesions, and this condition is histologically characterized by a lymphoplasmacytic infiltrate enriched in IgG4-positive plasma cells in the pleura. Although the pathogenesis of IgG4-RD is poorly understood, there is a growing body of evidence that indicates an antigen-driven process requiring T-cell and B-cell interaction in which autoantibodies, plasmablasts, follicular helper T cells and CD4+ cytotoxic T lymphocytes participate.

Summary

The possibility of IgG4-related pleural lesion should be considered in patients with pleural effusion of unexplained cause when lymphoplasmacytic infiltration is seen in a pleural biopsy specimen. This condition is responsive to systemic steroid therapy.

IgG4-related disease with elevated adenosine deaminase in pleural effusion diagnosed clinically using thoracoscopy under local anesthesia and FDG-PET-CT

In general, we have to assume tuberculous pleurisy when a patient presents with pleural effusion and elevated adenosine deaminase (ADA). However, other diseases need to be considered, including immunoglobulin (Ig)G4-related disease (IgG4-RD). This case involved a 65-year-old asymptomatic man with right pleural effusion showing elevated ADA. He had no articular findings or rashes. Results were negative for all autoantibodies. Pleura, mediastinal lymph nodes, and areas around the aorta and vertebra showed high uptake of ¹⁸F-fluorodeoxyglucose (FDG) on positron-emission tomography-computed tomography (PET-CT). These findings were specific for IgG4-RD. Based on the results of FDG-PET-CT, we performed thoracoscopy under local anesthesia and bronchoscopy. Pleural biopsy and culture, and other examinations including sputum and blood yielded negative findings for tuberculous pleurisy. A pleural biopsy specimen showed IgG4-positive plasma cells and fibrosis without obliterative phlebitis or storiform fibrosis, and serum IgG4 was also high. The ratio of IgG4-to IgG-positive plasma cells was under 40%, and >10 IgG4-positive cells were seen in high-power fields. This case was classed as ‘possible IgG4-RD’ on the comprehensive diagnostic criteria for IgG4-RD, but did not meet the diagnostic criteria for IgG4-related respiratory disease. Prednisolone proved effective against the pleural effusion. We therefore clinically diagnosed IgG4-RD with pleural effusion based on the 2019 classification criteria for IgG4-RD in the United States. Although few cases of IgG4-RD with pleural effusion have been reported, this disease needs to be considered among the differential diagnoses for high-ADA pleural effusion. FDG-PET-CT and thoracoscopy under local anesthesia may be helpful for diagnosis.

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ImmunoglobulinG4-related disease (IgG4-RD) with pleural effusion is rare.

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We should assume IgG4-RD as one of the differential diagnoses of pleural effusion with high level of adenosine deaminase.

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Thoracoscopy under local anesthesia and 18F-Fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET-CT) may be useful as an adjunctive tool for making a diagnosis of IgG4-RD.

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We could diagnosed as IgG4-RD with pleural effusion based on findings of FDG-PET-CT and thoracoscopy, and the responsiveness to prednisolone.

IgG4-related pleural disease with aortitis and submandibular glands involvement successfully treated with corticosteroid: case-based review

IgG4-related disease (IgG4-RD) is a fibro-inflammatory condition characterized by increased serum IgG4 level, infiltration of lymphocytes and IgG4-positive (IgG4⁺) plasma cells and fibrosis. It can occur in almost all organs, commonly affecting the pancreas, biliary tract, salivary and lacrimal glands and kidneys. However, reports of IgG4-RD accompanied by pathologically confirmed, IgG4-related pleural disease are scarce. Here, we present a case of a 64-year-old man with suspected malignant pleural mesothelioma based on imaging findings but finally diagnosed with IgG4-RD (including pleuritis, periaortitis and bilateral submandibular gland enlargement) based on a high serum IgG4 level and pleural histopathological findings such as lymphoplasmacytic infiltration including IgG4⁺ plasma cells and fibrosis. Systemic corticosteroid therapy was effective at reducing serum IgG4, improving bilateral submandibular gland enlargement, and regressing pleural thickening and periaortic soft tissue. We also discuss clinical characteristics and pleural pathological features of previously reported cases with IgG4-related pleural disease based on a comprehensive literature review. Our case of IgG4-RD with pleura, aorta and submandibular gland involvement, pathologically confirmed by pleural specimen might be unique and very rare.

Characteristics of pleural effusion in IgG4-related pleuritis

Here we describe the case of a 78-year-old man with respiratory failure and right pleural effusion. Computed tomography showed right pleural effusion with pleural calcification, tumor-like shadows induced by passive atelectasis, and enlarged mediastinal lymph nodes. Positron emission tomography showed right pleural thickening, rounded atelectasis, and enlarged mediastinal lymph nodes, without fluid accumulation in other organs. The pleural effusion showed lymphocyte-dominated exudates with elevated adenosine deaminase (ADA) levels. Tuberculous pleuritis was suspected, but thoracoscopic pleural biopsy revealed lymphoplasmacytic infiltration and fibrosis, with 10 immunoglobulin G4 (IgG4)-positive plasma cells/high-power field, and IgG4/IgG ratio of 40%. IgG4 concentrations in serum and right pleural effusion were 929 and 1120 mg/dL, respectively. The patient was diagnosed with IgG4-related pleuritis without other systemic manifestations, and reduction in right pleural effusion was confirmed by corticosteroid therapy. IgG4-related disease is typically a systemic disease causing lymphoplasmacytic inflammation in multiple organs. We describe a rare form of IgG4-related pleuritis showing pleural effusion with no other systemic manifestation.

Thoracoscopic Findings in IgG4-related Pleuritis

A 46-year-old Japanese man was admitted to our hospital with a 1-year history of dyspnea and persistent right-dominant bilateral pleural effusions. Chest and abdominal computed tomography (CT) revealed no notable findings apart from the bilateral pleural effusions. 2-deoxy-2-[18F]-fluoro-D-glucose (FDG) positron emission tomography-CT showed no accumulation of FDG in the thorax and abdomen. Thoracoscopy revealed numerous small (approximately 2-3 mm in size), blister-like nodules on the left parietal pleura extending from the lower third of the chest wall to the diaphragm. A pathological examination revealed lymphocyte and plasma cell infiltrates with increasing numbers of IgG4-positive plasma cells in the fibrotic pleura, indicating IgG4-related pleuritis.

IgG4-related pleural disease in a patient with a history of unknown origin acute pancreatitis: a case report and review of the literature

Immunoglobulin G4-related disease is a rare autoimmune systemic disease with the capability of involving every organ. The disease is microscopically defined by a diffuse tissular inflammation with an infiltration of IgG4 positive plasma cells in the affected organs. IgG4 disease has an increasing incidence in the last few years with a growing interest in its pathophysiology still misunderstood to date. Despite the growing recognition of this pathology, the literature still does not allow to propose a simple diagnostic algorithm. In this article, we present a case of a 56-year-old man with a history of unknown etiology acute pancreatitis and a unilateral pleural effusion.

Long-term spontaneous remission with active surveillance in IgG4-related pleuritis: A case report and literature review

Pleural effusion is a relatively rare feature of IgG4-related disease (IgG4-RD). Here, we report a case of a 72-year-old woman who presented with pleural effusion. Although the pleural adenosine deaminase level was increased, surgical biopsy of the pleura and left inguinal lymph node indicated that the effusion was due to IgG4-RD. Active surveillance was initiated because serum IgG4 and pleural effusion naturally decreased and then completely disappeared. The patient has shown no recurrence for >4 years. This case suggests that pleural biopsy can be used to distinguish IgG4-RD from tuberculosis; moreover, some cases with pleural effusion could improve without treatment.

IgG4-related Pleuritis with Elevated Adenosine Deaminase in Pleural Effusion

An 81-year-old man was admitted with bilateral pleural effusion. A clinical examination showed lymphocytic pleura effusion and elevated serum IgG4 levels, so that IgG4-related disease was suggested, whereas tuberculous pleurisy was suspected because of high adenosine deaminase (ADA) levels in the pleural effusion. A surgical pleural biopsy revealed that there were large numbers of IgG4-positive cells and IgG4/IgG positive cell ratio exceeded 40% in several sites. Accordingly, we diagnosed IgG4-related pleuritis and treated with the patient with glucocorticoid therapy. The ADA levels in pleural effusion can increase in IgG4-related pleuritis, and it is therefore important to perform a pleural biopsy.

IgG4-Related Pleuritis With No Other Organ Involvement

A 65-year-old man was admitted for productive cough and dyspnea. Bilateral pleural effusions were observed on chest X-ray. Although the bilateral pleural effusions were exudative with an increased number of lymphocytes, bacterial culture and polymerase chain reaction analysis for Mycobacterium tuberculosis were negative. Immunological examinations showed high levels of immunoglobulin G4 (IgG4) in both serum and pleural effusion fluid. Pathologic evaluation of a left pleural biopsy specimen using hematoxylin and eosin staining and immunohistochemical staining showed fibrosis-associated lymphoplasmacytic infiltration, 50 IgG4-positive plasma cells per high-power field, and an IgG4/IgG ratio of 40%. Thus, a diagnosis of IgG4-related pleuritis without other systemic manifestations was established. The bilateral pleural effusion improved following corticosteroid therapy. This is a rare case of IgG4-related pleuritis with no other organ involvement.

IgG4-related Disease - A Systemic Disease that Deserves Attention Regardless of One's Subspecialty

IgG4-related disease (IgG4-RD) is an inflammatory condition characterized by a high serum IgG4 concentration and the abundant infiltration of lymphocytes and IgG4-positive plasma cells in the tissue, as well as spatial (diverse clinical manifestations) and temporal (the possibility of recurrence) multiplicities. Since the initial documentation of IgG4-related disease in patients with autoimmune pancreatitis in 2001, a growing body of evidence has been accumulating to suggest that various-virtually all-organs can be affected by IgG4-RD. In general, steroid therapy is effective and is considered to be the first-line treatment for IgG4-RD. The precise mechanism underlying this systemic disorder has remained unknown. Considering that IgG4-RD was specified as being an intractable disease in 2015, further studies are needed to clarify whether IgG4-RD is indeed a distinct disease entity or a complex of disorders of different etiologies and clinical conditions.

IgG4-related disease involving polyserous effusions with elevated serum interleukin-6 levels: a case report and literature review

Immunoglobulin G4-related disease (IgG4-RD) is a recently described immune-mediated fibroinflammatory disease with a characteristic histopathologic appearance that can affect various organs. We report a 43-year-old Chinese female patient with IgG4-RD involving polyserous effusions with reports of worsening exertional dyspnea for 3 months. Laboratory blood tests revealed that serum interleukin (IL)-6, carbohydrate antigens (CA-199 and CA-125), and alpha-fetoprotein levels were significantly increased, but serum IgG4 levels were normal. Repeat pleural effusion and ascite analysis showed lymphocyte-predominant exudates. In addition, computed tomography scan showed massive pleural effusion in the right pleural cavity, abdominal effusion, and some pericardial effusion with a partial compression atelectasis. Further, medical thoracoscopy was performed to examine the pleural cavity and found multiple nodules on the pleura and partly thickened pleura with a reddish color. Histopathologic and immunohistochemical examination revealed marked lymphocytes and IgG4-positive plasma cell infiltration. The patient was finally diagnosed with IgG4-RD according to the comprehensive diagnostic criteria, although the patient presented similar serological and pathological manifestations of Castleman disease (CD). Our case suggests that IgG4-RD may be one of the causes of polyserous effusions and shows the difficulties in differentiating between IgG4-RD and CD.

An initial exploration for comprehensive assessment of IgG4-related lung disease: analyses on the cases enrolled from a systematic review

Background

The existence of two diagnostic systems, the Boston and Japan criteria, for immunoglobulin G4-related disease (IgG4-RD) confuse the medical practice. We aimed to develop a comprehensive assessment based on the weight of each diagnostic item in the existing criteria to improve the diagnostic efficiency of Boston criteria.

Methods

We assessed the patients enrolled by a systematic review of the literatures using the Boston criteria, Japan criteria and a tentative comprehensive assessment respectively, and evaluated the efficiency of each system and their consistency.

Results

Our analysis showed that the distinction in pathological diagnostic items was similar for the Boston criteria (IgG4+/IgG+ ratio, P<0.01; the number of pathological features and IgG4+ count, P<0.001) and comprehensive assessment (IgG4+/IgG+ ratio and the number of pathological features, P<0.001; IgG4+ count, P<0.05). For the Japan criteria, a good distinction in the number of pathological features was demonstrated (P<0.05) but the difference in the IgG4+/IgG+ ratio and IgG4+ count was not significant. There was relatively poor consistency between the Boston and Japan criteria (Kappa =0.482, P<0.001), while there was good agreement (Kappa =0.811, P<0.001), but a significant difference (P=0.011, McNemar matching test), between the Boston criteria and comprehensive assessment.

Conclusions

The current two diagnostic systems have poor consistency. Comprehensive assessment has good agreement with the Boston criteria, but can identify those cases in Boston Category 3 who could still be diagnosed as IgG4-related lung disease. Considering the weight of diagnostic items, the scoring system is a tentative exploration that should be improved with further experience in diagnosing IgG4-related lung disease.

Association of immunoglobulin G4 and free light chain with idiopathic pleural effusion

The cause of pleural effusion remains uncertain in approximately 15% of patients despite exhaustive evaluation. As recently described immunoglobulin (Ig)G4-related disease is a fibroinflammatory disorder that can affect various organs, including the lungs, we investigate whether idiopathic pleural effusion includes IgG4-associated etiology. Between 2000 and 2012, we collected 830 pleural fluid samples and reviewed 35 patients with pleural effusions undiagnosed after pleural biopsy at Yamaguchi-Ube Medical Center. Importantly, IgG4 immunostaining revealed infiltration of IgG4-positive plasma cells in the pleura of 12 patients (34%, IgG4⁺ group). The median effusion IgG4 level was 41 mg/dl in the IgG4⁺ group and 27 mg/dl in the IgG4^- group (P < 0·01). The light and heavy chains of effusion IgG4 antibodies of patients in the IgG4⁺ group were heterogeneous by two-dimensional electrophoresis, indicating the absence of clonality of the IgG4 antibodies. Interestingly, the κ light chains were more heterogeneous than the λ light chains. The measurement of the κ and λ free light chain (FLC) levels in the pleural fluids showed significantly different κ FLC levels (median: 28·0 versus 9·1 mg/dl, P < 0·01) and κ/λ ratios (median: 2·0 versus 1·2, P < 0·001) between the IgG4⁺ and IgG4^- groups. Furthermore, the κ/λ ratios were correlated with the IgG4⁺ /IgG⁺ plasma cell ratios in the pleura of the IgG4⁺ group. Taken together, these results demonstrate the involvement of IgG4 in certain idiopathic pleural effusions and provide insights into the diagnosis, pathogenesis and therapeutic opportunities of IgG4-associated pleural effusion.

Immunoglobulin G4-related pleuritis - A case report

Immunoglobulin G4-related disease (IgG4-RD) is a chronic disease that presents with inflammation and fibrosis of involved tissue. It encompasses several disorders previously described using different terms, but all disorders are characterised by IgG4-positive plasma cells and lymphocytes infiltration of tissues. We report a rare case of a 58-year-old man with IgG4-related pleural disease without other systemic manifestations. The diagnosis was based on characteristic changes on PET-CT and typical histopathology in a pleural specimen. The patient’s condition improved following immunosuppressive therapy.

Serosal involvement in IgG4-related disease: report of two cases and review of the literature

IgG4-related disease (IgG4-RD) is a recently described entity characterized by lymphoplasmacytic infiltrates, usually mimicking tumors, affecting almost every organ or system. Nevertheless, serosal involvement has been rarely reported. In this article, we report two cases of IgG4-RD with serosal involvement and review the literature. Because of the varied clinical pictures found in our review, we suggest a new terminology for the description of IgG4-RD with serosal involvement.

IgG4-related pleuritis with chylothorax

Presently, 6 cases of IgG4-related pleuritis have been reported. We encountered a patient who developed chylothorax due to IgG4-related disease. To our knowledge, such patients have not been reported. This patient developed right-sided chylothorax and left-sided non-chylothorax lymphocyte-predominant pleuritis. Elevated serum and pleural IgG4 concentrations and histopathological analysis of pleural biopsy confirmed the diagnosis of IgG4-related pleuritis. Left-sided pleuritis improved with corticosteroid therapy, but right-sided chylothorax persists. IgG4-related disease can be one cause of chylothorax.