IgG4-related diffuse perineural disease

A 55-year-old woman had right exophthalmia. Eleven years previously, she had orbital irradiation for refractory nonspecific orbital inflammation. PET/CT revealed FDG uptake in the right orbit and paravertebral masses (figure 1, A and C). MRI showed an enlargement of the right optic nerve and orbital muscles, and a diffuse infiltration involving lumbodorsal and sacral nerve roots (figure 1, B and D). The orbital biopsy demonstrated immunoglobulin...