IgG4-related disease: a neuro-ophthalmological perspective.

Immunoglobulin G4-related disease (IgG4-RD) is a multifocal inflammatory disorder that causes tumefactive lesions with a dense lymphoplasmacytic infiltrate rich in IgG4 plasma cells and storiform-pattern fibrosis. The clinical symptoms are relatively mild, and the condition is usually recognized by organ swelling and damage. When referring to the ophthalmic manifestations of IgG4-RD, the term IgG4-related ophthalmic disease (IgG4-ROD) is used. IgG4-ROD is characterized by bilateral lacrimal gland enlargement accompanied by 3 distinctive features: infraorbital nerve enlargement, extraocular myositis, and compressive optic neuropathy. IgG4 implies an underlying systemic disease process requiring evaluation to detect other systemic involvement. This includes hypophysitis and hypertrophic pachymeningitis, entities of neuro-ophthalmic interest. IgG4-ROD usually responds favorably to systemic corticosteroids but may be complicated by relapse during steroid taper. Rituximab has been shown to be effective for controlling steroid-refractory IgG4-RD. In contrast to IgG4-RD, an increasing number of cases of extranodal marginal B-cell lymphoma (MALT type) associated with IgG4-ROD have been described. IgG4 may be a risk factor for later emergence of low-grade B-cell lymphoma.