Orbital immunoglobulin-G4-related disease: case series and literature review.

Immunoglobulin-G4-related disease (IgG4-RD) is a distinct group of diseases characterized by elevated serum IgG4 titres and infiltration of affected organs by IgG4-positive plasma cells. IgG4-RD can involve any ocular adnexal tissue. They have a distinct prognosis and pattern of tissue involvement and hence need to be differentiated from orbital lesions with similar clinicopathological features. We report three cases of IgG4-RD and review the literature extensively discussing various aspects of this novel entity.