Seronegative granulomatosis with polyangiitis presenting with multiple cranial nerve palsies

Granulomatosis with polyangiitis (GPA), previously known as Wegener's granulomatosis (WG), is a rare systemic disease characterized by necrotizing granulomas and vasculitis that usually presents in the respiratory tract and renal system. Here, we report a case of anti-neutrophil cytoplasmic antibody (ANCA)-negative GPA with diagnostic difficulties. Neurologic involvement in GPA is not uncommon, with up to 50% of patients manifesting with neurologic defects; however, it is usually a late event. This patient was a 50-year-old man whose first manifestation was multiple neurologic defects without respiratory or renal symptoms. Since multiple neurologic deficits were the first manifestation and there were no pulmonary or renal symptoms, our patient was treated for 1 year for suspected infectious or inflammatory diseases such as non-tuberculous mycobacterial infection or immunoglobulin G4 (IgG4)-related disease with brain involvement; however, his symptoms would wax and wane. Reanalysis of the laboratory findings including biopsies, finally revealed this case to be compatible with GPA. Here, we report a case of GPA, focusing on the diagnostic pitfalls.