Immunoglobulin G4-related lung disease: Clinicoradiological and pathological features

Background and objective Immunoglobulin G4 (IgG4)‐related disease is a multi‐organ disorder that can include the lungs. IgG4‐related lung disease can present in various forms; the clinical, radiological and pathological features of patients with this disease have been assessed. Methods Forty‐eight patients suspected of having IgG4‐related lung disease, with a high serum concentration of IgG4 and abundant IgG4‐positive plasma cell infiltration into the intrathoracic organs, were retrospectively evaluated. Their clinical features, chest imaging findings and pathological findings were examined, with final diagnoses made by an open panel conference. Results Of the 48 patients, 18 with extrathoracic manifestations were diagnosed as having IgG4‐related lung disease. Most of these patients were middle‐aged to elderly men. IgG4‐related lung disease was characterized by high serum concentrations of IgG and IgG4, normal white blood cell count and serum C‐reactive protein concentration and a good response to corticosteroids. Common radiological findings included mediastinal lymphadenopathy and thickening of the perilymphatic interstitium, with or without subpleural and/or peribronchovascular consolidation. Pathological examination showed massive lymphoplasmacytic infiltration with fibrosis in and around the lymphatic routes, with distribution well correlated with radiological manifestations. Conclusions The findings suggest that the intrathoracic manifestations of IgG4‐related lung disease develop through lymphatic routes of the lungs and show various clinical characteristics. Because some lymphoproliferative disorders show similar findings, the correlation of clinicoradiological and pathological characteristics is crucial for the diagnosis of IgG4‐related lung disease. The clinicoradiological and pathological features of IgG4‐RLD were assessed. Clinically, this disease is silent, although radiological and pathological examinations showed that it involves lymphatic routes, with spread observed on imaging and infiltration on pathological examination. Clinicoradiological and pathological correlation is necessary for the diagnosis of this disease.