An Exceptional GPA: Granulomatosis with Polyangiitis Presenting as Hypertrophic Pachymeningitis

Background: Granulomatosis with polyangiitis (GPA) is a necrotizing vasculitis usually involving small blood vessels that has been described to rarely effect the meninges, presenting with headaches and in our case papilledema. Thickened dura mater may be seen on brain imaging and is an entity known as hypertrophic pachymeningitis. We present a case of isolated dural recrudescence of ANCA vasculitis. Case Presentation: A 62-year-old man with known anti-GBM disease and history of ANCA positivity who remains dialysis dependent after initial diagnosis and treatment eight months prior presents to the emergency department from his ophthalmologist’s office due to headaches, vision changes, and severe bilateral papilledema. Initial head imaging with computed tomography revealed hypertrophic pachymeningitis and lumbar puncture revealed elevated opening pressure of 38 cm H2O. Further workup was unremarkable, including persistently negative ANCA titers. Ultimately dural biopsy led to diagnosis of GPA with isolated dural involvement, likely representing recrudescence from his original diagnosis eight months prior. He was started on IV steroids, underwent plasmapheresis, and started on rituximab with symptomatic improvement. Conclusions: Hypertrophic pachymeningitis is a rare phenomenon that can be caused by GPA. Prompt recognition and treatment of increased intracranial pressure is essential to avoid vision loss and life-threatening complications.