IgG4-related lung disease

Pulmonary involvement is common in IgG4-related disease, an idiopathic entity characterized by tumorous growths involving multiple organ systems, elevated IgG4 levels, and characteristic histopathology manifested by lymphoplasmacytic infiltrate, fibrosis, obliterative phlebitis, and tissue infiltration with IgG4-positive plasma cells. Mediastinal adenopathy is present in nearly all patients, and pulmonary involvement takes the form of pulmonary nodules or masses (most common), consolidation, interstitial infiltrates, and thickened bronchovascular bundles. Diagnosis rests on elevated IgG4 levels, characteristic histopathology, and the exclusion of other conditions that may be associated with similar clinical and histopathologic findings. Treatment is usually but not always needed; most patients respond to steroids at least initially, but relapses are common. Experience with other therapies is limited. This review summarizes the current literature on pulmonary manifestations of IgG4-related disease.