Hypertrophic pachymeningitis (HP) is characterized by inflammation of the dura mater. It has been described in the setting of numerous systemic inflammatory diseases including immunoglobulin G4 (IgG4)-related disease as well as granulomatosis with polyangiitis (GPA). In this case report, we describe a 48-year-old man presenting with headache who was found to have HP and had systemic features of both GPA and IgG4-related disease as well as seropositivity for both cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA) and IgG4. He was treated with prednisone and rituximab with improvement in his symptoms. Co-occurrence of IgG4 and ANCA against myeloperoxidase has been reported in other cases of HP. The overlap between IgG4 and ANCA has also been described in other systemic manifestations of the diseases. These reports suggest a clinical overlap between ANCA and IgG4-related disease, and the case presented herein suggests an overlap between GPA and IgG4-related disease.