Pancreatic Inflammation Induced by Immune Checkpoint Inhibitors in Melanoma Treatment: A Case Report

BACKGROUND Immunotherapy has seen an exponential increase recently, as has the study of its associated adverse effects. Although a wide range of reactions to immunotherapy has been described, reports of immune-mediated focal pancreatitis remain rare. Autoimmune pancreatitis related to immune checkpoint inhibitors occurs because of the hyperactivation of T lymphocytes, which act against pancreatic cells, causing inflammation. CASE REPORT This case report describes a previously healthy 41-year-old man with a diagnosis of metastatic melanoma with inguinal lymph node metastasis. The patient underwent 1 year of adjuvant treatment with nivolumab and had excellent tolerance. After a 1-year suspension of this treatment, nodal and peritoneal recurrence occurred, leading to the initiation of combined therapy with ipilimumab and nivolumab, followed by maintenance nivolumab, resulting in a complete response. After 10 cycles of nivolumab, PET-CT and MRI identified a lesion in the head of the pancreas, which was suspected to be a primary neoplasm. The patient was asymptomatic, with normal tumor markers and elevated amylase and lipase levels. An endoscopic ultrasound-guided biopsy was performed to rule out primary pancreatic cancer, revealing moderately active chronic inflammation associated with immunotherapy. Nivolumab treatment was interrupted for 2 weeks, during which pancreatic enzyme levels improved. Treatment was resumed thereafter. The patient continued with monthly nivolumab applications, maintaining a complete response. without changes in imaging or laboratory test results. CONCLUSIONS This case is atypical for autoimmune pancreatitis owing to the absence of corticosteroid intervention, self-limiting nature of inflammation, and lack of inflammatory recurrence despite the continued use of immunotherapy.