How would you approach a male in his 60s with bilateral optic perineuritis/neuritis on MRI, steroid-responsive bilateral jaw pain, normal ESR/CRP, negative temporal artery biopsy, and elevated IgG4?  

This is a challenging case with a number of atypical features. When approaching such a scenario, I try to categorize the presenting clinical features by their specificity. In this case, optic perineuritis has a broad differential, including MOG, MS, sarcoidosis, SLE, systemic vasculitis, and infecti...