A 54-year-old man presented with a chief complaint of fever and pain around the left clavicle. He had a primary germ cell tumor of the mediastinum and had been undergoing chemotherapy for approximately six months. To prevent myelosuppression, pegfilgrastim was administered after each chemotherapy session. Pegfilgrastim was administered 4 days before the onset of fever and pain. On examination, he had a body temperature of 38.1 °C and pain in the left arm. Laboratory findings showed elevated C-reactive protein level (19.4 mg/dL).
