Idiopathic Sclerosing Orbital Inflammation

Abstract

We read with great interest the report by Levin et al (1) regarding the role of the optic nerve biopsy in the management of progressive optic neuropathy. We had the opportunity to evaluate a 50-year-old man with progressive deterioration of vision in his left eye for 2 months with minimal periocular pain. Visual acuity was 20/20, right eye, and no light perception, left eye. The right fundus was normal but there was marked optic disc edema in the left eye (Fig. 1). Magnetic resonance imaging (MRI) of the brain and orbits demonstrated enhancement and thickening of the left optic nerve (Fig. 2). An extensive work-up including hematologic tests, lumbar puncture, and computed tomography of chest, abdomen, and pelvis was unremarkable. The patient was given 1 g of methylprednisolone intravenously for 3 days followed by a tapering dose of oral steroids over several months. Although there was improvement in the left optic disc edema, vision remained unchanged.FIG. 1: Left fundus shows marked optic disc edema with peripapillary hemorrhages.FIG. 2: Postcontrast axial (A) and coronal (B) T1 magnetic resonance imaging with fat suppression shows thickening and enhancement of the left optic nerve.Four months after onset of symptoms, the patient reported vision loss in the right eye. Acuity was 20/40, right eye, and no light perception, left eye. Funduscopy revealed right optic disc edema and left optic atrophy. MRI demonstrated thickening of the right optic with marked enhancement following intravenous contrast. Prednisone was restarted at a dose of 1 mg/kg/d, and there was rapid improvement in the vision in the right eye with resolution of right optic disc edema. Given involvement of the previously unaffected right eye, a biopsy of the left optic nerve was performed. Histopathology showed primarily fibrosis and an inflammatory infiltrate consisting of lymphocytes, histiocytes, and plasma cells (Fig. 3). No granulomas were identified. Stains for infectious, immune, and neoplastic disorders were nondiagnostic. Based on these results, a diagnosis of idiopathic sclerosing orbital inflammation (ISOI) was made.FIG. 3: Biopsy demonstrates optic nerve and sheath fragments with marked fibrosis accompanied by an inflammatory infiltrate of lymphocytes, histiocytes, and plasma cells (periodic acid–Schiff, ×400).ISOI is a rare condition characterized by marked fibrosis and some inflammatory infiltrate (2–4). However, unlike idiopathic orbital inflammation, which has an acute clinical onset, the progression of ISOI generally has a chronic and indolent course (5). In our patient, there was consecutive involvement of both optic nerves. There are reports of ISOI associated with systemic idiopathic fibrosis and increased serum levels of IgG4 (6,7). Our patient did not show increased serum levels of IgG4, and the biopsy specimen was negative for the presence of IgG4.