IgG4-related disease presenting as recurrent scleritis combined with optic neuropathy

We report a case of atypical presentation of IgG4-related disease (IgG4-RD) with recurrent scleritis and optic nerve involvement. A 61-year-old male presented with ocular pain and injection in his left eye for 2 months. Ocular examination together with ancillary testing led to the diagnosis of scleritis, which relapsed in spite of several courses of steroid treatment. After cessation of steroid, the patient complained of severe retro-orbital pain and blurred vision. His best corrected vision was count finger, the pupil was mid-dilated and a relative afferent pupillary defect was found. Funduscopic examination demonstrated disc swelling. Magnetic resonance imaging (MRI) showed enhancing soft tissue encasing the left globe, medial rectus muscle and optic nerve. Systemic work-up revealed multiple nodules in right lower lung and a biopsy showed histopathological characteristics of IgG4-RD. Long-term treatment with corticosteroids and a steroid-sparing agent (methotrexate) led to significant improvement in signs and symptoms with no recurrence for 2 years. This case highlights the significance of IgG4-RD in the differential diagnosis of recurrent scleritis. IgG4-RD may cause optic neuropathy resulting in visual loss. Early diagnosis and proper treatment can prevent irreversible organ damage and devastating visual morbidity.