Intrathoracic manifestations of immunoglobulin G4-related disease: A pictorial review

Immunoglobulin G4-related disease (IgG4-RD) is an increasingly recognized systemic fibro-inflammatory disease associated with elevated serum IgG4 levels. It affects virtually any organ system including the gastrointestinal system, salivary glands, periorbital tissues, kidneys, lungs, lymph nodes, central nervous system, large vessels, thyroid, and skin. Although the involved organ systems vary between studies and are influenced by the medical center and specialty, the most frequent manifestation of IgG4-RD is regarded to be type 1 autoimmune pancreatitis. The incidence of intrathoracic involvement is not known exactly, but it is thought to be relatively rare. Intrathoracic manifestations of IgG4-RD can be observed in airways (tracheobronchial stenosis, thickening of bronchovascular bundles), pulmonary parenchyma (nodules, masses, interstitial lung disease), pleura (pleural thickening, nodules, effusion), and mediastinum (lymphadenopathy, fibrosing mediastinitis). This review aimed to briefly describe the pathogenesis, histopathology, clinical features, diagnosis, and treatment of IgG4-RD; and make a pictorial review of its intrathoracic manifestations.