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A 51-year-old woman with a previous history of rheumatoid arthritis experienced painless progressive visual loss in the left eye for 3 weeks. Fundus examination revealed optic disk pallor in her left eye. Magnetic resonance imaging of the brain and orbits showed enhancement of the pachymeninges and hypersignal at the left optic nerve. Meningeal biopsy was performed. Immunohistochemical staining for IgG4 revealed several IgG4-positive plasma cells, which in some areas reached the number of 50 cells/high-power field. In this case, the clinical and histopathological features of the patient met diagnostic criteria for rheumatoid arthritis and IgG4-related disease, respectively. Rheumatoid arthritis sometimes occurs with abundant IgG4 plasma cells and fulfills the histological diagnostic criteria for IgG4-related disease. This case demonstrates that overlapping features of IgG4-RD and rheumatoid arthritis may present in a single patient.