Pancreatitis as immune‐related adverse event during pembrolizumab therapy for multiple lung metastases from renal pelvic cancer

Introduction Pembrolizumab administration has become the standard of care for patients with urothelial carcinoma, though a variety of adverse events have been reported. Presented here is a rare case of pancreatitis that occurred as an immune‐related adverse event. Case presentation An 81‐year‐old man undergoing treatment with pembrolizumab for multiple lung metastases from renal pelvic cancer was presented with a fever and diagnosed with pancreatitis based on elevated pancreatic enzyme levels and imaging findings. There was no history of alcohol consumption or findings indicating gallstones, elevated liver enzymes, or abdominal complications. The patient was diagnosed with immune‐related adverse event pancreatitis and treated with Lactate Ringer's solution (3000 mL/day) and steroids, during which his condition improved. Conclusion Although pancreatitis is a rare complication, it should always be considered as a potential immune‐related adverse event in patients treated with an immune checkpoint inhibitor such as pembrolizumab.