Teaching neuroimages: IgG4-related orbital disease and enlargement of the trigeminal nerve branches.

A 54-year-old man had a 5-year history of painless bilateral eyelid swelling, proptosis, and diplopia. MRI showed enlargement of extraocular muscles, lacrimal gland, and divisions of the trigeminal nerve (figure 1). Biopsy from the left infraorbital canal demonstrated lymphoplasmacytic infiltrate and fibrosis. Mean number of immunoglobulin G (IgG)41 cells was 155 per high-power field and ratio of IgG41/IgG1 cells was 89% (figure 2). Figure 1 Brain MRI findings