Pathological findings of lgG4-related lung disease

IgG4-related disease (IgG4-RD) causes temporally and spatially diverse lesions in systemic organs, with respiratory organ involvement now known to include the bronchi, bronchioles, alveolar wall, pleura, pulmonary vessels, and mediastinal lymph nodes. The histopathological features of the lesion site are a marked lymphoplasmacytic infiltrate, diffusely distributed IgG4-positive plasma cells, and obliterative inflammation of arteries and/or veins. Some non-neoplastic lung diseases, whose cause was hitherto unknown, may be encompassed in this disease. Many such disorders must now be reconsidered in light of information emerging about IgG4-RD.