Case Presentation:
A 62 year old male with history of rapidly progressive glomerulonephritis due to anti-glomerular basement membrane (anti-GBM) disease who remains dialysis dependent after failing to respond to steroids and plasmapheresis eight months ago presented with two months of worsening vision and frontal headaches. The patient also has chronic systolic heart failure with an implantable cardiac defibrillator (ICD). Outpatient ophthalmologic exam revealed severe bilateral papilledema prompting hospital admission. Further history was remarkable for positive myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) at the time of his initial anti-GBM diagnosis. Both ANCA and anti-GBM titers have since been within the normal range and there were no other symptoms of recrudescent MPO-ANCA or anti-GBM disease.
As a consequence of headaches and visual disturbances imaging of the brain was required. MRI was excluded due to his ICD so CT of the brain was obtained which revealed dural thickening concerning for hypertrophic pachymeningitis with diminished caliber of the superior sagittal and straight sinuses. Lumbar puncture revealed elevated opening pressure of 38 cm H2O, 10 WBC/µL, 3401 RBC/µL, protein 137 mg/dL, and glucose 64 mg/dL. He experienced temporary symptomatic improvement on acetazolamide while work-up was pending. Extensive CSF studies including culture, cytology, acid fast bacilli smear, rapid plasma reagin, cryptococcal antigen, and angiotensin converting enzyme were negative. Serum anti-nuclear antibody and ANCA titers were negative.
The unclear etiology of pachymeningitis led to a biopsy of the dura that was 3-4 times normal thickness and granulomatous in appearance. Pathologic examination revealed necrotizing vasculitis involving the small vessels with granulomatous inflammation concerning for granulomatosis with polyangiitis (GPA). The patient was started on IV steroids, plasmapheresis, and rituximab.
Discussion:
Hypertrophic pachymeningitis is a rare condition involving inflammatory thickening of the dura mater which may lead to signs of increased intracranial pressure or cranial nerve palsies. Contrast-enhanced MRI facilitates diagnosis. Differential includes a number of infective and inflammatory processes such as sarcoidosis, syphilis, lymphoma, and ANCA vasculitis. GPA is necrotizing granulomatous vasculitis characterized by ANCA positivity which most often affects the nephrons and/or small airways. As in this case, active ANCA vasculitis may rarely present with involvement limited to the meninges, with negative ANCA titer, and requiring biopsy for diagnosis.
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. This case reminds the clinician that negative ANCA titers do not disprove recrudescence of the disease, and that vasculitis can have localized presentations in very unusual places.