Acute pancreatitis as the initial manifestation of an ampullary neuroendocrine tumor.

Acute pancreatitis is a common condition in Gastroenterology. Among its possible etiologies are ampullary tumors, rare neoplasms whose growth can hinder pancreatic drainage. Although they are usually epithelial, adenomas and adenocarcinomas, less commonly other histological types have been reported, such as neuroendocrine tumors. They constitute a small percentage of both ampullary tumors and neuroendocrine tumors of the digestive tract, classified into three histological grades based on mitotic count and Ki-67. Although the diagnosis is usually incidental, its main form of presentation is clinical or analytical cholestasis, with acute pancreatitis being an exceptional initial presentation. Endoscopic resection is the treatment of choice for well-differentiated tumors without evidence of local infiltration of the duodenal wall or intraductal growth greater than 10mm, with endoscopic ultrasound playing a key role in this assessment. We present the case of a 45-year-old cholecystectomized woman who was admitted to our service with a condition compatible with acute pancreatitis, initially suspected to be of biliary origin. After several radiological and endoscopic studies, an enlargement of the duodenal papilla suggestive of ampulloma was detected. Histological examination demonstrated a well-differentiated neuroendocrine tumor of the duodenal papilla which, lacking evidence of local duodenal infiltration or intraductal growth, was successfully resected endoscopically.