Abundant immunoglobulin (Ig)G4-positive plasma cells in interstitial pneumonia without extrathoracic lesions of IgG4-related disease: is this finding specific to IgG4-related lung disease?

Challenges and pitfalls in the diagnosis of IgG4-related disease

IgG4-related disease (IgG4-RD) is a relatively novel fibroinflammatory condition characterized typically by dense lymphoplasmacytic inflammation, storiform fibrosis and obliterative venulitis, together with prominent IgG4+ plasma cells and an IgG4+/IgG+ plasma cell ratio of >40 %. The diagnosis is usually made on a combination of clinical and serological features together with characteristic radiological and histological appearances. The condition may be limited to a single tissue/organ (e.g., autoimmune pancreatitis) or may be multicentric in nature - four clinical 'patterns' of disease distribution have recently been described. The diagnosis of IgG4-RD can be challenging, particularly when the clinical presentation is unusual and/or when the histological features are not typical. A diagnosis of IgG4-RD may still be achieved in these situations, after careful clinicopathological discussion e.g., at a specialist multidisciplinary team meeting. However, a wide range of other conditions (neoplastic and non-neoplastic) can mimic IgG4-RD, clinically and/or on histological examination. The relationship between IgG4-RD and non-IgG4-RD associated conditions in some clinical situations is particularly complex. This review describes the role of histological examination in the diagnosis of IgG4-RD, discusses some of the practical difficulties that may be encountered and provides an insight into the range of non-IgG4-RD associated conditions that can mimic IgG4-RD on clinical and/or histological grounds. The requirement for interpretation of histological features in the context of the global clinical picture of the patient is highlighted and emphasized.

Prognostic implication of IgG4 and IgG1-positive cell infiltration in the lung in patients with idiopathic interstitial pneumonia

Immunoglobulin (Ig) G4-positive cells are rarely observed in the lungs of patients with idiopathic interstitial pneumonias (IIPs). IgG1 may be more pathogenic than IgG4, with IgG4 having both pathogenic and protective roles in IgG4-related disease (IgG4-RD). However, the role of both IgG1 and IgG4 in IIPs remains unclear. We hypothesized that patients with IgG4-positive interstitial pneumonia manifest different clinical characteristics than patients with IgG4-RD. Herein, we identified the correlation of the degree of infiltration of IgG1- and IgG4-positive cells with IIP prognosis, using a Japanese nationwide cloud-based database. We included eighty-eight patients diagnosed with IIPs after multidisciplinary discussion, from April 2009 to March 2014. IgG4-positive cell infiltration was identified in 12/88 patients with IIPs and 8/41 patients with idiopathic pulmonary fibrosis (IPF). Additionally, 31/88 patients with IIPs and 19/41 patients with IPF were diagnosed as having IgG1-positive cell infiltration. IgG4-positive IIPs tended to have a better prognosis. Conversely, overall survival in cases with IgG1-positive IPF was significantly worse. IIPs were prevalent with IgG1- or IgG4-positive cell infiltration. IgG1-positive cell infiltration in IPF significantly correlated with a worse prognosis. Overall, evaluating the degree of IgG1-positive cell infiltration may be prognostically useful in cases of IPF.

Immunoglobulin G4-positive interstitial pneumonia associated with pleuroparenchymal fibroelastosis

A 79-year-old former smoking Japanese man was admitted to our hospital with a 2-year history of dry cough and dyspnoea on exertion. High-resolution computed tomography of the chest revealed reticulation and perilobular opacity with bronchial wall thickening and ground-glass opacities (GGOs) in both lungs, in addition to subpleural dense consolidation (pleuroparenchymal fibroelastosis-like lesion; PPFE-like lesion) predominantly in the bilateral upper lobes. Serum immunoglobulin G4 (IgG4) was elevated (348 mg/dl). Lung biopsy specimens obtained by video-assisted surgery revealed a mixture of usual interstitial pneumonia (IP) and non-specific IP pattern admixed with PPFE. In addition, immunohistochemical staining of IgG4 showed numerous IgG4-positive plasma cells. Consequently, he was diagnosed with IgG4-positive IP associated with PPFE. We initiated a combination therapy with prednisolone and cyclosporine as a calcineurin inhibitor. During prednisolone tapering, his clinical conditions and GGOs improved gradually over 12 months. However, reticular opacities and PPFE-like lesions remained unchanged, and pulmonary function test findings slightly deteriorated.

Immunoglobulin G4-related disease: case report and literature review

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is a rare and chronic progressive clinical entity, characterized by elevated serum IgG4 along with tissue infiltration by IgG4 + plasma cells. It is an immune-mediated fibro-inflammatory condition that can affect virtually any organ and tissue. IgG4-related lung disease (IgG4-RLD) occupies 14% of all IgG4-RD, with nonspecific symptoms and various abnormal radiographic patterns. Published data on IgG4-related hypertrophic pachymeningitis (IgG4-RHP), an increasingly recognized central nervous system manifestation of IgG4-RD, is also limited. Both lung and cranial dura involvement have not yet been reported until now. We further entail a review of the literature on the clinicopathologic features and differential diagnosis of this uncommon disease. We herein report an interesting case of a 70-year-old male patient admitted due to headache and fever. A magnetic resonance imaging (MRI) of the brain revealed extensive dural thickening with marked enhancement. Chest computed tomography (CT) scan showed nodular or mass-like consolidation and focal interstitial change. Thoracoscopic lung biopsy and lumbar puncture were conducted. After careful histopathological observation and consideration of alternative differential diagnoses, he was diagnosed with IgG4-related disease with lung and cranial dural involvement based upon significant elevation of serum and cerebrospinal fluid (CSF) IgG4 concentration. The patient was started on oral prednisolone 60 mg/day (1.0 mg/kg/day) for 14 days, and a tapering dose of 5 mg every 2 weeks followed by maintenance therapy at low dose for 3 months. His clinical manifestations, and serologic and imaging findings improved with steroid treatment. Currently, the patient remains well without disease progression. IgG4-RD should be considered as a differential when diagnosing other similar multisystemic lesions. Clinical examination, careful histological observation, and immunostaining for appropriate markers are essential in establishing the diagnosis. Clinicians should become familiar with this alternative differential diagnosis.

Interstitial pneumonia with autoimmune features that met the proposed diagnostic criteria for IgG4-related respiratory disease

We held a multidisciplinary discussion (MDD) about a 61-year-old woman who had an interstitial lung disease (ILD) without extrathoracic lesions that met the classification criteria for interstitial pneumonia with autoimmune features (IPAF) and the proposed diagnostic criteria for immunoglobulin G4 (IgG4)-related respiratory disease (IgG4-RRD). Clinically, the marked progression of lung-limited diffuse lesions was consistent with IPAF. Serum IgG4 and rheumatoid factor levels simultaneously increased and did not contribute to a diagnosis. Pathologically, the significant hyperplasia of lymphoid follicles was consistent with rheumatoid arthritis (RA)-associated ILD. Pulmonary venous occlusions by intimal fibrosis and intimal thickening were not important because these occlusions are found in IgG4-related lung disease (IgG4-RLD) and also in IPAF or ILDs related to connective tissue diseases (CTDs). Radiologically, fibrosing shadows that remained in the lung periphery after treatment were compatible with RA-associated chronic ILD. We concluded that the present case was IPAF that met the proposed diagnostic criteria for IgG4-RRD.

A case of eosinophilic granulomatosis with polyangiitis complicated with a similar condition to IgG4 related lung disease

BACKGROUND

Atypical manifestations, such as elevated serum immunoglobulin-G4 (IgG4) and extra-pulmonary IgG4 positive plasmacyte infiltration, have been described in patients with eosinophilic granulomatosis with polyangiitis (EGPA), such complicated situation might not be readily differentiated from IgG4-related disease.

CASE PRESENTATION

Here, we report an interesting and rare case of EGPA in a 41 year-old male with negative anti-neutrophil cytoplasmic antibodies (ANCAs), which showed abundant pulmonary IgG4-positive plasma cells infiltration and markedly elevated serum IgG4 levels without extra-pulmonary lesions of IgG4-related disease. The clinical characteristics hesitated us whether the diagnosis as EGPA overlapping with IgG4-related lung disease should be concluded because of the absence of storiform fibrosis and obliterative phlebitis with lymphoplasmacytic infiltration. The patient's systemic symptoms, pulmonary lesions, blood eosinophils count / percentage, and serum IgG4 levels were significantly improved with immunosuppressive therapy.

CONCLUSIONS

We consider that the overlapping pathogenesis exists in the disease course of EGPA and IgG4-related disease, which may lead to interaction during the course of the diseases. And the utilization of diagnostic criteria for IgG4-related lung disease with the careful differentiation is needed in such cases.

IgG4-related respiratory disease

IgG4-related diseases (IgG4-RDs), such as autoimmune pancreatitis and IgG4-related Mikulicz disease, are often accompanied by intrathoracic lesions, which are called IgG4-related respiratory disease (IgG4-RRD). IgG4-RRD has few subjective symptoms, and is usually detected during workup of patients with extra-thoracic lesions of IgG4-RD. IgG4-RRD is characterized by various conditions, including masses, nodules, thickening, and infiltration at numerous sites in the thorax through lymphatic routes. Although elevated serum IgG4 concentrations and pathologic evidence of lymphoplasmacytic infiltrates with abundant IgG4-positive plasma cells are characteristic findings of IgG4-RD, other intrathoracic diseases, such as multicentric Castleman disease and malignancy, may present with similar findings. Developing diagnostic criteria for IgG4-RRD, including clinicoradiological and pathological characteristics, is necessary for its appropriate diagnosis.

IgG4-related disease presenting with combined pulmonary fibrosis and emphysema (CPFE)

A 64-year-old man was admitted to our hospital with an abnormal chest shadow. The patient was a current-smoker and had a past illness of autoimmune pancreatitis with a high serum level of IgG4, 348 mg/dL. Chest CT showed upper-lobe emphysema, and lower-lobe reticulation with honeycombing, suggestive of combined pulmonary fibrosis with emphysema (CPFE). Surgical lung biopsy was revealed a usual interstitial pneumonia pattern with marked infiltration of IgG4-positive plasma cells. The patient was diagnosed with IgG4 related disease (IgG4-RD) presenting with CPFE. Pulmonary manifestation was improved by corticosteroid therapy. IgG4-RD may be an underlying condition in patient with CPFE.

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.

A case of immunoglobulin G4-related lung disease with bilateral diffuse infiltration: A case report

RATIONALE

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is a rare and chronic progressive autoimmune disease. It is a novel clinical entity characterized by elevated serum IgG4 concentration and tissue infiltration by IgG4 plasma cells. IgG4-related lung disease (IgG4-RLD) has been described as interstitial pneumonia and inflammatory pseudotumor, with various abnormal radiographic patterns. We report a case of IgG4-related lung disease with bilateral diffuse infiltration.

PATIENT CONCERNS

A 65-year-old woman was admitted to our hospital because of cough, sputum, and fever. Chest computed tomography (CT) revealed multifocal areas of consolidations, nodules, and ground glass opacities in both lungs. She still had fever after anti-infective therapy.

DIAGNOSES

Bronchial bronchoscopy and percutaneous lung biopsy were performed, resulted in a pathological diagnosis of IgG4-RLD.

INTERVENTIONS

The patient was started on oral prednisolone 30 mg/day for 28 days, and then was gradually tapered.

OUTCOMES

After one week treatment, the temperature was stable, CT showed significant improvement in the areas of consolidations and nodules.

LESSONS

It is a typical case of IgG4-RLD. This case indicated that suggestive evidence, radiological appearances, serum tests, pathological characteristics, and classic therapy IgG4-RLD. It is a rare disease that needs our more attention in future.

Desquamative Interstitial Pneumonia Complicated with IgG4-related Lung Disease

As an idiopathic interstitial pneumonia, desquamative interstitial pneumonia (DIP) is an uncommon form of interstitial lung disease and is considered to be a smoking- or dust inhalation-related interstitial pneumonia in the majority of cases. However, the details regarding immunoglobulin G4 (IgG4)-related lung disease remain unclear and controversial. We herein report the first case of DIP complicated with IgG4-related lung disease. Even if a patient has a smoking history, we emphasize the importance of exploring the association between DIP and IgG4-related lung disease to clarify the pathogenesis of these two disorders.