Lung and airway disorders in immunoglobulin G4- related disease

gG4-related disease (IgG4-RD) is an immune-mediated condition, characterized by the formation of fibroinflammatory tumefactive lesions that can cause progressive tissue damage and subsequent organ failure. Although initially described as a disease of unknown etiology confined to the pancreas, IgG4-RD has been realized over time as an important entity that has underlies numerous pathologic conditions such as autoimmune pancreatitis, Riedel thyroiditis, Mikulicz syndrome, inflammatory pseudotumors and many others. IgG4-RD can affect almost any organ. However, the most commonly affected are the pancreas, hepatobiliary system, exocrine glands (salivary, lacri mal), retroperitoneum, kidneys and intrathoracic structures. Within the thorax, involvement of the lung parenchyma, airways, mediastinum, and pleura have been reported. The pulmonary involvement, therefore, is very diverse and can present as pulmonary nodule(s) or mass(es), alveolar or interstitial infiltrates, airflow obstruction, lymphadenopathy, mediastinal fibrosis, and pleural thickening and/or effusion. It is therefore important to recognize the diverse manifestations of this condition, as it can involve multiple organs and have various forms of expression within the same organ. As a consequence, IgG4-RD has presented a fascinating diagnostic challenge for many different specialties. In this review, we focus on the diagnosis and management of the intrathoracic involvement in this multisystem disease