An 88-year-old Japanese man with Alzheimer's disease presented with fever that lasted for 1 day and arthralgia in the left shoulder. The patient had no history of trauma. On physical examination, his temperature was 38.4 °C, regular heart rate was 88 beats/min, blood pressure was 109/53 mmHg, respiratory rate was 12 breaths/min, and oxygen saturation was 99 % in room air. On the left shoulder joint, swelling, heat, tenderness, and a limited range of motion were noted. Laboratory tests revealed the following: white blood cell count, 10,300 /μL (normal range, 3300–6200 /μL), and C-reactive protein level, of 10.1 mg/dL (normal range, 0–0.14 mg/dL).
