A 66-year-old man presented with multiple progressive ulcers on the right side of his face that had developed over the past 3 months (Figure, A). He had also experienced a burning sensation on the right side of his face, but denied headache, shoulder, or jaw pain and visual disturbance. Neurological examination revealed hypoesthesia of the right side of the face, while cold-warm sensation and motor function were intact. The erythrocyte sedimentation rate was 82 mm per hour (normal value, less than 15 mm per hour) and the serum C–reactive protein concentration was 107 mg/L (normal value, less than 5 mg/L). Chest radiography showed bilateral perihilar infiltrates consistent with pneumonia. About 2 weeks before the ulcerations developed, the patient had been admitted to the hospital for unstable angina, and coronary angiography was performed. Immediately after the angiography, the patient developed left-sided hemiplegia and hemianopsia. Magnetic resonance imaging of the brain revealed an extensive ischemic posterior circulation stroke involving the right occipital lobe, lower cerebellar peduncle, and pontomedullary boundary (Figure, B).