An update on IgG4-related lung disease.

IgG4-related disease (IgG4-RD) is an autoimmune disorder characterized by substantial infiltration of plasma cells with IgG4 in target organs. Lung manifestations predominantly present as inflammatory pseudotumor, interstitial pneumonitis, organizing pneumonia, and lymphomatoid granulomatosis. There is no specific diagnostic test for IgG4-related lung disease (IgG4-RLD), and excluding diseases that mimic IgG4-RLD is important. Corticosteroids with or without disease-modifying anti-rheumatic drugs are recommended for treatment. The long-term prognosis of IgG4-RLD remains unknown. In this review, we summarized the current diagnostic algorithms and discussed potential biomarkers for future investigation.