S3627 A Rare Collision: Primary Sclerosing Cholangitis With Incidental Extrahepatic Biliary Neuroendocrine Tumor

Introduction: The co-occurrence of Primary Sclerosing Cholangitis (PSC) and Extrahepatic Biliary Neuroendocrine Tumors (EBNETs) is extremely rare. EBNETs account for <1% of neuroendocrine tumors and a small fraction of biliary tract cancers, with cystic duct involvement in only 16.7% of cases. PSC, typically linked to cholangiocarcinoma, is seldom associated with neuroendocrine tumors, making this case a unique and noteworthy finding. Case Description/Methods: A 59-year-old woman with a history of Sjogren’s disease and prior cholecystectomy for gangrenous cholecystitis presented with recurrent right upper quadrant (right upper quadrant) pain and elevated liver enzymes. Magnetic resonance cholangiopancreatography (MRCP) findings: Biliary stricture concerning for PSC. Surgical intervention: Roux-en-Y hepaticojejunostomy for recurrent cholangitis. Incidental finding: 3 mm low-grade neuroendocrine tumor (NET) at the cystic duct stump. Immunohistochemistry: Positive for chromogranin. Chromogranin A levels: Decreased from 266 to 2 postoperatively. Octreoscan: No residual disease. Over the next 3 years, the patient had recurrent cholangitis and diarrhea. Repeat MRCP showed a beaded appearance of the bile ducts, confirming PSC progression. Colonoscopy revealed microscopic Crohn’s disease. She was treated with ursodiol and ciprofloxacin but experienced continued disease progression, leading to liver transplant consideration. Discussion: PSC diagnosis is complex, particularly when complicated by malignancy. Incidental EBNETs in PSC patients are rare, highlighting the need for thorough histopathologic evaluation. While surgical resection improved biochemical markers, PSC progression necessitated long-term monitoring. Management of PSC focuses on symptom control, malignancy surveillance, and transplant evaluation. This case underscores the importance of vigilance in PSC patients due to its association with rare malignancies. Early detection, multidisciplinary care, and tailored surveillance strategies are crucial for optimizing outcomes. Further research is needed to understand the molecular links between PSC and EBNETs and improve screening protocols for high-risk patients.