Pancreatic Colloid Carcinoma Arising From Intraductal Papillary Mucinous Neoplasm in the Setting of Gallbladder Agenesis, Ansa Pancreatica, and Santorinicele: Follow-Up of a Previously Reported Case.

This report details the long-term follow-up of a patient previously reported from our centre with recurrent acute pancreatitis and episodic jaundice in the setting of three rare anatomic variants: gallbladder agenesis, ansa pancreatica, and a santorinicele. The index report described progressive main pancreatic duct dilatation and endoscopic findings consistent with intraductal papillary mucinous neoplasm (IPMN) despite non-diagnostic cross-sectional imaging. We now present the subsequent clinical course, including elective pancreaticoduodenectomy, definitive histopathology, and surveillance outcomes. Histopathology demonstrated a 30 mm grade 2 pancreatic colloid carcinoma arising in association with an intestinal-type IPMN involving both main and branch ducts (pT2N1). This occurred despite the absence of a discrete mass or guideline-defined high-risk features on cross-sectional imaging. The postoperative course was complicated, and later remnant duct dilatation raised concern for a late pancreaticojejunostomy stricture. The patient's symptoms subsequently improved, and duct calibre decreased on surveillance imaging, with computed tomography (CT) imaging in February 2025 confirming no recurrence of malignancy. This longitudinal case demonstrates that guideline-negative cross-sectional imaging does not exclude invasive carcinoma in suspected IPMN, particularly when pancreatitis and ductal variants confound interpretation. It supports individualised management, multidisciplinary assessment, and timely consideration of resection in selected patients.