Immunoglobulin G4-related inflammatory pseudotumor of the lung.

An 82-year-old man presented with a nodule in the right S(2)a of the lung as seen by chest computed tomography (CT). He had undergone treatment for chronic obstructive lung disease. He had a 53-year history of smoking 20 cigarettes a day. Subsequent to the appearance of the nodule in the right S(2)a, the CT images revealed consolidations in the right S(2)b, right S(3), and left S(5). The nodule in the right S(2)a was diagnosed as squamous cell carcinoma after performing video-assisted thoracoscopic wedge resection of the lung. After 4 months, the size of the consolidation in the right S(2)b increased. Recurrence of lung cancer was suspected. Using transbronchial lung biopsy, the consolidation in the left S(5) was diagnosed as organizing pneumonia; therefore, right upper lobectomy was performed. The consolidations in the right S(2)b and right S(3) were diagnosed as inflammatory pseudotumors with infiltrations of immunoglobulin G4-positive plasma cells.