[A Case of Hypophysitis Due to Immune Check Point Inhibitor Treatment]

The patient was a man in his 70s with bone metastasis from renal cell carcinoma who had received immune checkpoint inhibitors(ICI)therapy. After 2 courses of chemotherapy, he was admitted to our hospital with diverticulitis. His diverticulitis could be treated with antibiotics, but he presented with severe hyponatremia and consciousness disorder during hospitalization. Brain MRI showed pituitary swelling, and his serum TSH, ACTH, cortisol levels decreased. We therefore diagnosed him with hypopituitarism due to ICIs. Hydrocortisone improved his hyponatremia and consciousness disorder. Endocrine stimulation tests revealed no reaction of ACTH, and low-level reactions of TSH, LH and FSH, ICIs cause many types of immune- related adverse events(irAEs). The indications for ICI therapy are expanding; thus, we can expect to experience more cases of serious irAEs in association with ICI treatment. Further studies should be performed to improve our understanding of irAEs.