Isolated Myeloperoxidase–Antineutrophil Cytoplasmic Antibody–Associated Hypertrophic Pachymeningitis

A 65-year-old man with no pertinent medical history presented with 1 month of progressive holocephalic positional headaches (worse supine), photophobia, progressive gait instability resulting in multiple falls (ambulatory to walker in only 2 months), and weight loss. Testing found positive ANCA 1:160 perinuclear patter, myeloperoxidase >8.0. Cerebrospinal fluid found lymphocytic pleocytosis. We present his neuroimaging of isolated hypertrophic pachymeningitis with clinicoradiographic resolution after immunomodulatory pharmacotherapy along with histology from his meningeal biopsy. Isolated vasculitic myeloperoxidase-antineutrophil cytoplasmic antibody hypertrophic pachymeningitis is quite rare.