p-ANCA pachymeningitis presenting with isolated "optic neuropathy".

Isolated bilateral optic neuropathy is an exceedingly rare presentation of perinuclear-antineutrophil cytoplasmic autoantibody (p-ANCA) vasculitis. We report one such case with MRI documentation of a compressive mechanism mediated by pachymeningitis. A 69-year-old woman had a 6-month history of progressive visual failure caused by bilateral optic neuropathy. Cranial MRI showed diffuse contrast enhancement of the dura mater extending to the perioptic sheaths bilaterally with encasement of the optic nerves. Extensive laboratory study showed increased levels of p-ANCA titres and autoimmune markers. Corticosteroid treatment improved both visual acuity and the neuroradiological signs of active pachymeningitis. In conclusion, our case demonstrates that bilateral optic neuropathy may be the presenting symptom of p-ANCA-associated pachymeningitis, whose causative role may be demonstrated by MRI.