Abstract
INTRODUCTION: The use of immune checkpoint inhibitors (ICIs) is gradually increasing; ICIs produce a variety of immune-related adverse events (irAEs), especially ICI-induced hypoadrenocorticism, which can be a lethal complication if treatment is delayed. PATIENT CONCERNS: A 63-year-old man received chemotherapy with pembrolizumab for nonsmall cell lung cancer. He developed drug-induced interstitial pneumonia 366 days after receiving pembrolizumab and was treated with prednisolone. Five hundred thirty-seven days later, he developed drug-induced eosinophilic enteritis, and pembrolizumab was discontinued and prednisolone was continued. After discontinuation of prednisolone, general malaise and edema of the lower extremities appeared, and adrenal insufficiency was suspected. DIAGNOSIS: In blood tests on admission adrenocorticotropic hormone (ACTH) was 2.2 pg/mL and cortisol was 15 μg/dL, with no apparent cortisol deficiency. However, the cortisol circadian rhythm disappeared and remained low throughout the day; a corticotropin-releasing hormone stimulation test showed decreased reactive secretion of ACTH. Pituitary magnetic resonance imaging showed pituitary emptying, suggesting Empty Sella syndrome. INTERVENTIONS AND OUTCOMES: We started hydrocortisone and his symptoms were improved. CONCLUSIONS: The administration of high-dose steroids after ICI administration may mask the symptoms of hypoadrenocorticism as irAEs. Therefore, we should bear in mind the possibility of hypoadrenocorticism when we stop steroid therapy in patients who are treated with steroids after ICI administration.