Initial Presentation of Granulomatosis with Polyangiitis as Progressive Skull Base Osteomyelitis

A healthy man in his 30s presented with a 2-week history of severe bitemporal pain and pressure. He was initially treated for presumed acute rhinosinusitis, but his symptoms continued to worsen and underwent endoscopic sinus surgery at an outside community facility. He developed left abducens nerve palsy postoperatively, and magnetic resonance imaging (MRI) demonstrated evidence of extensive skull base osteomyelitis. He was initiated on intravenous (IV) broad-spectrum antibiotics but was subsequently found to have prostatic and submandibular sterile fluid collections. The patient subsequently developed new right abducens and left vagal nerve palsies and underwent revision endoscopic sinus surgery. Pathology revealed extensive inflammation, necrotizing granulomas, and evidence of small and medium vessel vasculitis. Extensive laboratory workup was negative, except for anti-PR-3 antibody positivity. Given the characteristic findings on pathology and laboratory findings, the patient was diagnosed with granulomatosis with polyangiitis (GPA). High-dose glucocorticoid therapy as well as rituximab infusion were promptly initiated. He had marked improvement in his symptoms and resolution of his right CN VI palsy but left-sided CN VI and CN X palsies persisted. This patient presented without the typical rhinologic manifestations of GPA, and rather presented with progressive sinusitis, skull base osteomyelitis with associated cranial neuropathies, and aseptic systemic abscesses. Prompt diagnosis of GPA is particularly important in those with otorhinolaryngological manifestations, as early initial immunosuppressive therapy has been linked to lower relapse and mortality rates. Vigilance and early differentiation between GPA and other forms of sinusitis is of critical importance, particularly when symptoms are refractory to standard rhinosinusitis therapies.