IgG4 disease.

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is a chronic inflammatory disorder characterized by elevated serum level of IgG4 and abundant infiltration of IgG4-bearing plasmacytes and fibrosis in various organs, typically including the lacrimal glands, salivary glands, pancreas, thyroid gland, lungs, and kidneys. Lacrimal and orbital involvements are called IgG4-related ophthalmic disease, often presenting as orbital myositis, perineuritis of the optic and trigeminal nerves, and orbital inflammation. In particular, a characteristic finding is infraorbital nerve enlargement on magnetic resonance imaging. Systemic screening is necessary to establish the diagnosis of IgG4-RD, and it must be distinguished from neoplastic disease. Corticosteroid treatment is effective in inducing remission but some patients may relapse during tapering of pharmacotherapy. This review encompasses the history, clinical profile, diagnostic criteria, treatment, and prognosis of IgG4-RD.