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.