IgG4-Related Lung Disease Presenting as a Consolidative Mass: A Case Report

ABSTRACT

Immunoglobulin G4 (IgG4)-related sclerosing disease involving the lung is a rare condition, and this is characterized by an elevated serum IgG4 level, fibrotic inflammation with numerous IgG4-positive plasma cells and a response to steroid therapy. We present here a case of pulmonary IgG4-related disease in a 75-year-old man who presented with cough and yellowish sputum for the previous 3 months. The chest images showed a consolidative mass in the right lower lobe that suggested mucinous bronchioloalveolar carcinoma. The wedge resected specimen revealed an ill-defined gray-tan, firm lesion. Microscopically, the lesion showed a diffuse lymphoplasmacytic infiltration with irregular fibrosis in the alveolar interstitium and bronchovascular bundles. There were numerous IgG4-positve plasma cells and these cells were diffusely distributed. The serum IgG4 level was elevated on the postoperative check-up (249 mg/dL). After corticosteroid therapy for 7 months, the patient's symptoms and radiologic abnormalities were improved.