Idiopathic orbital inflammation: a new dimension with the discovery of immunoglobulin G4-related disease

Purpose of review To review idiopathic orbital inflammation, with particular reference to the evolving entity of ocular adnexal immunoglobulin G4 (IgG4) disease. Recent findings Emerging evidence suggests that sclerosing idiopathic orbital inflammation can be an IgG4-related disease and discovery of this link has further reduced the subset of 'idiopathic orbital inflammation'. Ocular adnexal IgG4 disease should especially be considered if the orbital disease is bilateral or where there is systemic involvement. New reports are linking the possibility of lymphoma arising from a background of IgG4-positive inflammation in both the orbit and in other organs, and both the physician and the patient should be aware of this long-term risk. Summary Although the diagnosis of IgG4-related orbital disease continues to be challenging, there is a growing understanding of the pathophysiology and this is likely to be key to developing a clinical strategy for the diagnosis and effective treatment of this condition.