Antineutrophil cytoplasmic antibody-associated pachymeningitis: a systematic review of clinical features, diagnosis and treatment outcomes.

Antineutrophil cytoplasmic antibody (ANCA)-associated pachymeningitis is a rare inflammatory disorder of the dura mater that may occur in isolation or as part of systemic vasculitis. The clinical features and outcomes of proteinase 3 (PR3)- and myeloperoxidase (MPO)-ANCA-associated pachymeningitis remain poorly defined. We aimed to synthesize clinical presentation, investigations, and treatment outcomes to improve diagnosis and guide management. A systematic review was conducted in accordance with PRISMA guidelines. PubMed, Embase, and Scopus were searched to June 15, 2023. Eligible studies were case reports or series of patients with imaging-confirmed pachymeningitis and positive ANCA serology. Individual patient data were extracted, including demographics, clinical features, pathology, and outcomes. We identified 230 patients from 177 reports, including 108 MPO-ANCA-positive, 71 PR3-ANCA-positive, and 3 dual MPO/PR3-positive cases; 46 ANCA-positive cases had unspecified antigen specificity, and 2 were ELISA-negative but ANCA IIF-positive. Median age was 60 years; 53% were male. Headache and cranial neuropathies-particularly hearing loss, visual impairment, and diplopia-were predominant. Systemic involvement was present in 89% of cases, primarily affecting the ear, nose, throat, lungs, orbits and kidneys. Imaging often showed tentorium/falx, middle cranial fossa, and frontal convexities involvement. Inflammatory markers were raised in > 90%, and cerebrospinal fluid pleocytosis in 50%. Typical pathological features such as granulomas, vasculitis, or necrosis were documented in 66% of biopsied patients. At a median 9-month follow-up, mortality rate was 3.9% and relapse rate 23.5%. Rituximab (25%) was associated with lower rates of refractory disease. PR3- and MPO-ANCA-associated pachymeningitis typically presents with headache and cranial neuropathies, usually with systemic involvement. Relapse and incomplete recovery remain common despite treatment, underscoring the need for early recognition, targeted immunotherapy, and long-term follow-up.