Benign Imitation of Malignancy: Avoiding Resection in Immunoglobulin G4–Related Lung Disease

We report the case of a 32-year-old woman who presented with cough, pleuritic pain, and a solitary lung mass. Computed tomography demonstrated a 3.7-cm spiculated right lower lobe mass, and 18-fluoro-deoxy-glucose positron emission tomography/computed tomography demonstrated significant hypermetabolism, both most suggestive of invasive adenocarcinoma. The results of fine needle aspirate biopsy favored a benign inflammatory process. Video-assisted thoracoscopic surgery right lower lobectomy was performed, and histopathologic examination of the mass was consistent with immunoglobulin G4–related disease (IgG4-RD). A definitive diagnosis of IgG4-RD often requires correlating several nonspecific findings with surgical lung biopsy. We discuss important diagnostic and treatment considerations for pulmonary IgG4-RD.