Fatal Granulomatosis with Polyangiitis Presenting as Medial Longitudinal Fasciculus Syndrome with Gastrointestinal Perforation: An Autopsy Case Report.

We report a rare and fatal case of granulomatosis with polyangiitis (GPA) initially presenting as medial longitudinal fasciculus (MLF) syndrome. A 64-year-old man with a history of duodenal ulcer and hypertension presented with diplopia. Neurological examination revealed impaired adduction of the left eye with preserved convergence, consistent with MLF syndrome. Brain magnetic resonance imaging showed multiple high-intensity lesions, including one in the left dorsal pons. Laboratory testing revealed an elevated PR3 antineutrophil cytoplasmic antibody level of 205 IU/mL. A kidney biopsy on day 18 revealed crescentic necrotizing glomerulonephritis, confirming the diagnosis of GPA. Corticosteroid pulse therapy was initiated, but gastrointestinal perforation occurred on day 26, requiring extensive gastrectomy. Pathology revealed ulcerative changes and neutrophil infiltration, but no vasculitic lesions. Because of hepatic dysfunction from hepatitis C virus infection, escalation of immunosuppressive therapy was not feasible. On day 111, the patient developed a second gastrointestinal perforation, leading to sepsis and death on day 136. Autopsy revealed duodenal perforation and multiple cerebral infarctions corresponding to prior magnetic resonance imaging findings. No definitive vasculitic lesions were identified. This case highlights an unusual central nervous system onset of GPA as MLF syndrome. Antineutrophil cytoplasmic antibody-associated vasculitis should be considered even in patients with atypical neurological manifestations, and prompt diagnosis and treatment are essential.