IgG4-Related Pleural Disease Diagnosed by a Re-Evaluation of Chronic Bilateral Pleuritis in a Patient Who Experienced Occasional Acute Left Bacterial Pleuritis

A 78-year-old man with cryptogenic chronic bilateral lymphoplasmacytic pleuritis, diagnosed based on left parietal pleural biopsy specimens obtained by pleuroscopy, developed acute left bacterial pleuritis. The left pleural effusion was neutrophil dominant, however, the right pleural effusion showed lymphoplasmacytic infiltration. Laboratory examinations revealed that his serum IgG4 concentration was increased, with a higher level of IgG4 in the...