Radiographic Patterns of Orbital Involvement in IgG4-Related Disease

Abstract

Immunoglobin G4 (IgG4)-related disease is a systemic condition characterized by lymphoplasmacytic infiltrates that can involve the orbit. The purpose of this study was to identify the various patterns of orbital IgG4-related disease on imaging. Retrospective review of radiologic examinations including CT, MRI, and positron emission tomography was performed in patients with proven cases of IgG4-related disease. A total of 9 patients with orbital IgG4-related disease were identified, including 9 with CT, 4 with MRI, and 4 with 18-fluorodeoxyglucose positron emission tomography. Patterns of involvement included lacrimal gland enlargement, lacrimal sac involvement, extraocular muscle thickening, preseptal involvement, orbital fat involvement, and cranial nerve involvement, many of which occurred simultaneously. Associated demineralization of the orbital wall was evident on CT in 2 cases. On T2-weighted MRI, the lesions appeared as hypointense in 2 cases, heterogeneously hypointense to isointense in 1 case, and hyperintense in 1 case. Diffuse enhancement was present in all 3 cases in which postcontrast T1-weighted sequences were available. The lesions were hypermetabolic on positron emission tomography in 3 of 4 cases. There was definite extraorbital involvement by IgG4-related disease in 3 of the 9 patients and suspected involvement in another 3 of the 9 patients. IgG4-related disease displays a wide variety of imaging manifestations in the orbit. Extraorbital disease is often present and can help suggest the diagnosis.