Abstract
Background. There have been few reports of pancreatitis occurring as an immune-related adverse event of pembrolizumab. Case. The patient was a 46-year-old man with lung adenocarcinoma cT3N0M1c, stage IVB. The tumor proportion score (TPS) was 70%, and he received pembrolizumab as first-line chemotherapy. Although his tumor had shrunk, he noticed mild pain in the upper abdominal area after the sixth administration of pembrolizumab and visited our emergency room because the abdominal pain had worsened. Computed tomography revealed sausage-like diffuse enlargement of the pancreas, and a blood test showed elevated levels of amylase and lipase. Based on these findings, we suspected that pancreatitis had developed as an adverse event of pembrolizumab. We discontinued the administration of pembrolizumab and immediately initiated methylprednisolone therapy (60 mg/day). Over three weeks, the pain gradually disappeared, the pancreas decreased in size, and the amylase level returned to within the normal range. Although a blood test did not show an increase in the IgG4 level, the pancreatitis was similar to autoimmune pancreatitis based on the imaging findings and the good response to steroid therapy. Conclusion. We encountered a case of pancreatitis occurring as an immune-related adverse event after pembrolizumab therapy with autoimmune pancreatitis-like image findings and a good response to steroid therapy. We should pay careful attention when using pembrolizumab, as pancreatitis can sometimes occur.
