Hypertrophic pachymeningitis with co-occurrence of anti-neutrophil cytoplasmic antibodies and immunoglobulin G4 seropositivity: Case report and literature review.

We report an extremely rare case of hypertrophic pachymeningitis in which a 71-year-old man presented with an intractable recurrent headache for >1 year. During this period, he became positive for immunoglobulin G4 and proteinase 3-antineutrophil cytoplasmic antibodies. Contrast-enhanced magnetic resonance imaging showed characteristic diffuse thickening of the dura. Symptoms were improved by intravenous methylprednisolone (500 mg per day for 5 days) and cyclophosphamide pulse therapy during corticosteroid withdrawal; he remained symptom-free during 1-year follow-up. This case suggests that this disease can be treated by corticosteroids combined with immunosuppressive agents.