Relapsing polychondritis after treatment with PD-1 blockade.

Nivolumab, a programmed death 1 blockade drug, is used in various types of cancers and can cause a unique immune-related adverse event (irAE). Relapsing polychondritis (RP) is a rare autoimmune disease that mainly involves inflammation of the auricle, nose and airway cartilage. A 72-year-old man with mandibular cancer received nivolumab after surgery for the primary lesion and radiation therapy for lung metastases. He then developed radiation pneumonitis, and prednisolone (PSL) was started. During the tapering of PSL, he developed exertional dyspnea and cough. The condition of mandibular cancer and radiation pneumonitis had not deteriorated. Fluorodeoxyglucose (FDG)-PET/CT showed a thickening of and abnormal FDG uptake in the tracheobronchial and nasal septum cartilage. These characteristic findings were not observed before nivolumab was initiated; thus, we clinically diagnosed the patient as having RP induced by nivolumab. Since the symptoms were mild, the patient's condition was carefully managed with inhaled corticosteroids, and the RP has not progressed thus far. Physicians should be aware that RP can occur as an irAE because RP may progress to serious respiratory symptoms.