Abstract
Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory disorder
that has been recognized to involve virtually any organ in the body and typically
manifests mass-like lesions (tumefactive). Although initial reports of this disease
(autoimmune pancreatitis [AIP]) were described in the Japanese population, it has
since been reported worldwide. It is most commonly seen in adults of middle age or
older, more often men than women. The pathogenesis of IgG4-RD is largely unknown,
but genetic factors, microorganisms, and autoimmunity are thought to play important
roles. Serum IgG4 concentration is elevated in the majority of patients with IgG4-RD
but is a nonspecific finding. Characteristic histopathologic features include dense
lymphoplasmacytic infiltrate, fibrosis (often in storiform pattern), and obliterative
phlebitis. Lung involvement in IgG4-RD was first reported in 2004 in two patients
with AIP and coexisting interstitial lung disease. Since then, a wide spectrum of
intrathoracic involvement has been reported and includes not only parenchymal lung
diseases but also pleural, airway, vascular, and mediastinal lesions. Thoracic involvement
in IgG4-RD is often found incidentally during the workup of extrathoracic lesions
but can sometimes be the presenting abnormality. The diagnosis of IgG4-RD requires
correlation of clinical, laboratory, imaging, and histopathologic features. Glucocorticoids
are the first-line therapy but other options including B cell depletion are being
investigated. IgG4-RD is generally associated with an indolent clinical course and
most patients improve with glucocorticoid therapy.
Keywords
IgG4-RD - fibroinflammatory - pseudotumor - interstitial lung disease - pleuritis
- lymphadenopathy