A Case of IgG4-Related Disease Presenting With Concurrent Uveitis, Posterior Scleritis, Serous Retinal Detachment, and Choroidal Thickening Mimicking Intraocular Lymphoma.

IgG4-related disease (IgG4-RD) is a systemic fibro-inflammatory condition characterized by tumor-like lesions, dense lymphoplasmacytic infiltrates rich in IgG4-positive plasma cells, and often elevated serum IgG4 levels. Ocular involvement is common, typically affecting the lacrimal glands and extraocular muscles. However, intraocular manifestations such as uveitis and scleritis are less frequent. We report the case of a 66-year-old Japanese man presenting with bilateral uveitis, posterior scleritis, serous retinal detachment, and choroidal thickening, initially mimicking intraocular lymphoma. His serum IgG4 and soluble interleukin-2 receptor levels were markedly elevated. Magnetic resonance imaging showed posterior eyeball wall thickening with restricted diffusion and diffuse thickening of the nasal mucosa and hard palate mucosa. Computed tomography revealed an asymptomatic retroperitoneal mass around the aorta. Salivary gland biopsy confirmed dense lymphoplasmacytic infiltration with increased IgG4-positive plasma cells (80/HPF) and an elevated IgG4/IgG ratio (~50%), consistent with IgG4-RD. The patient responded well to oral corticosteroid therapy with improvement in visual acuity. This case highlights the rare but important presentation of intraocular manifestations in IgG4-RD.