Immunoglobulin-G4-related hypertrophic pachymeningitis with antineutrophil cytoplasmatic antibodies effectively treated with rituximab.

We describe a 52-year-old man with hypertrophic pachymeningitis (HP) who was both seropositive for antineutrophil cytoplasmatic antibodies (ANCA) against myeloperoxidase, and had an immunoglobulin G4 (IgG4) positive fibroinflammatory response in meningeal biopsy. HP is a chronic inflammatory thickening of the dura mater which typically presents with headache, cranial nerve dysfunction and other neurological deficits. While first-line treatment with corticosteroids is recommended, many patients relapse and need additional immunosuppression. One recently described etiology is IgG4-related disease and in a subgroup of idiopathic patients, evidence suggests a crucial role of ANCA. To our knowledge, the simultaneous occurrence of IgG4-related disease and ANCA has not been reported so far. This man suffered life-threatening disease progression despite the administration of high dose steroids, cyclophosphamide and azathioprine. Treatment with rituximab was initiated which led to disappearance of clinical symptoms and decrease of dural thickening within weeks. This patient presents a possible disease overlap of IgG4-related and ANCA-associated HP and illustrates the effectiveness of rituximab in refractory IgG4-related HP.