Orbital inflammatory disease

Orbital inflammatory disease (OID), commonly known as orbital pseudotumour, is an inflammatory disease of unknown cause. It has different forms of presentation and different degrees of severity. Its variable nature is the main cause for this disease to be misdiagnosed and misclassified. The prognosis of OID depends on the tissues affected and the histology. OID usually responds favourably to systemic steroid treatment. However, empiric steroids may mask other underlying diseases that respond well to this treatment as well, namely, IgG4-related disease or lymphoproliferative disorders. This fact has led to controversy among various authors as some recommend performing a biopsy in most of the cases, whereas others defend that this procedure should only be performed if the patient has not responded to empiric steroid treatment. Although steroids have been the mainstream treatment of OID, the side effects, relapse rates and lack of response in some cases have resulted in them being replaced by immunosuppressive and immunomodulator therapies that currently stand as a key steroid-sparing treatment option, in addition to radiotherapy and surgery. The aim of this review is to update the evidence on the diagnosis and treatment of OID.