IgG4-related pleural disease

IgG4-related disease (IgG4-RD) is a newly recognized chronic systemic fibroinflammatory disease that displays protean manifestations. Since the initial description of IgG4-related pancreatitis (type 1 autoimmune pancreatitis), it has become clear that IgG4-RD can involve virtually any organ in the human body including intrathoracic structures. It is characterized by infiltration of IgG4-positive plasma cells and fibrosis in affected organs. IgG4-RD affects mainly adults, more commonly men. Most commonly described form of pulmonary involvement is focal parenchymal opacities. However, other forms of parenchymal involvement such as diffuse interstitial infiltrates have been reported as well as airway, vascular, mediastinal, and pleural disease. Pleural disease in IgG4-RD can present as pleural mass, pleuritis with fibrosis, or pleural effusion. IgG4-related pleural disease can present with or without concomitant parenchymal lung lesions or extrapulmonary manifestations of IgG4-RD. In patients presenting with fibroinflammatory disease involving the pleura of obscure cause, possible role of IgG-RD should be considered.