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

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.