[Unusual visual impairments in a case of MPO-ANCA associated hypertrophic pachymeningitis].

We report a 79-year-old man presenting MPO-ANCA associated hypertrophic pachymeningitis and bilateral visual impairment. Two years before, microscopic hematuria and positive MPO-ANCA were indicated, then oral steroids and cyclophosphamide were given as systemic vasculitis. On admission, lateral hemianopsia in the right visual field was documented. Some weeks after admission, he complained of a left-hand side headache, and the visual impairment of a right eye. Brain MRI detected thick dura matter with abnormal enhancement predominantly on the left side of the basal temporal lobe and a tumor-like lesion at the sphenoid sinus near the right cavernous sinus. Multiple scotomas in the left visual field were compatible with ischemic changes caused by MPO-ANCA related vasculitis. On the other hand, the hemianopsia in his right eye was related with a tumor-like lesion. The visual problems showed a favorable response to the steroid pulse therapy. ANCA-positive cases can demonstrate various symptoms including intra-/extra-cranial involvement. Thus, thorough clinical workup is needed to determine the actual site of the lesion when cranial nerve involvement is observed in MPO-ANCA positive hypertrophic pachymeningitis.