Granulomatosis with polyangiitis (GPA) is a systemic autoimmune disease that causes necrotizing vasculitis of small- to medium-sized blood vessels and necrotizing granulomatous inflammation, primarily of the upper and lower respiratory system.

A 33-year-old woman presented with a 16-month history of headaches, nasal obstruction, and anosmia. She was diagnosed with GPA based on the saddle nose deformity, septal perforation, rhinitis, sinusitis, retro-orbital mass, hearing loss, hypertrophic pachymeningitis, thinned skull base bone, proteinase 3–antineutrophil cytoplasmic antibody positivity, and histopathological findings of nasal granulomatous lesions. The remission induction therapy with high-dose glucocorticoids (GCs) and intravenous cyclophosphamide ameliorated the GPA. Three months later, headaches worsened with diplopia and liquorrhea. Computed tomography revealed enlarged septal perforation, exacerbated sinusitis, skull base bone defects, and continuous air from the right olfactory fissure into the cranium (Figure 1A). Contrast-enhanced magnetic resonance imaging revealed inflammation of the posterior ethmoid sinus, and a ring-shaped high-signal area at the base of the frontal lobe (Figure 1B). The patient underwent a craniotomy to close the defects, and her recovery included long-term antibiotics therapy for cerebral abscess, remission induction therapy with high-dose GCs, and rituximab for recurrent GPA. She maintained remission for 2 years.

(A) Sagittal plane of computed tomography of the head, revealing intracranial air (white arrowheads). (B) Horizontal plane of contrast-enhanced magnetic resonance imaging of the head, revealing cerebral abscess (white arrowheads).

Approximately 8% of patients with GPA have central nervous system damage,1 but pneumocephalus is extremely rare. Chronic sinusitis, hypertrophic pachymeningitis, and thinned skull base bone can be risks for pneumocephalus.2,3 Intense immunosuppressive treatment might result in the rapid formation of cerebral abscess. Careful observation is needed when treating patients at risk for pneumocephalus and cerebral abscess in GPA.