Auto-Immune Pancreatitis with Pseudo-Tumoral Mass Induced by Pembrolizumab in a Woman suffering from Metastatic Urothelial Carcinoma: Case Report and Literature survey.

Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy but may induce rare immune-related adverse events including pancreatitis (ICI-PI-), which occurs in 2-4% of cases. Such ICI-PI may necessitate treatment discontinuation. We report the rare case of a 51-year-old female with Lynch syndrome treated with pembrolizumab for metastatic urothelial carcinoma. A pancreatic mass was identified during follow-up by PET/CT. Pathology from endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) could not exclude adenocarcinoma. Surgical resection revealed pathology consistent with type II autoimmune pancreatitis (AIP) in a case which represent by definition , a type III ICI-PI. We explore diagnostic criteria focusing on clinical, serological, histological as well as medical imaging features and management.