Idiopathic Orbital Inflammation Syndrome with Retro-Orbital Involvement: A Retrospective Study of Eight Patients

BACKGROUND The aim of this retrospective study was to document the clinical findings and radiological features of idiopathic orbital inflammation syndrome with retro-orbital involvement. METHODS We searched for ophthalmological patients who received orbital imaging at Zhejiang Provincial People's Hospital between October 2003 and April 2010. Seventy-three patients were diagnosed with idiopathic orbital inflammation syndrome based on clinicoradiological features, with pathological confirmation of nonspecific inflammatory conditions in 47 patients. Eight patients (11%) had MRI or CT evidence of retro-orbital involvement. All 8 patients were diagnosed with idiopathic orbital inflammation syndrome after biopsy of the orbital lesion. MR images were obtained for all 8 patients; 3 patients also had a contrast-enhanced CT scan. RESULTS Seven out of 8 patients with retro-orbital involvement also had orbital apex lesions. Of the 65 patients without retro-orbital involvement, 19 had orbital apex lesions. The difference in the number of patients with orbital apex lesions between the two populations was significant (Fisher exact test P = .002). In all 8 patients with retro-orbital involvement, the inflammation spread through the superior orbital fissure. The retro-orbital lesions were isointense to grey matter on T1-weighted images, hypointense on T2-weighted images, and displayed uniform contrast enhancement; on contrast-enhanced CT scans, they were hyperdense relative to the contralateral mirror area and had radiological contours that were similar to those seen on MR images. The diffuse inflammation with marked sclerosis and hyalinization that we observed in the patients with retro-orbital involvement is consistent with the diagnosis of the sclerosing subtype of idiopathic orbital inflammation syndrome. All 8 patients also complained of mild to moderate periorbital pain (headache). CONCLUSIONS In patients with idiopathic orbital inflammation syndrome, it is important to perform MRI and CT scans to identify possible retro-orbital involvement. Retro-orbital involvement is more frequent when the lesion is present in the orbital apex.