P2334 - Polypoid Puzzle: A Hidden Mucinous Biliary Cystadenoma Revealed in a Novel Fashion by Spyglass and ERCP Contrast Retention With Literature Review

Shyam Vedantam, DO¹, Alan S. Livingstone, MD¹, Jodie A. Barkin, MD, FACG²
1University of Miami/Jackson Memorial Hospital, Miami, FL; 2University of Miami Miller School of Medicine, Miami, FL

Introduction: Biliary cystadenomas are rare, potentially malignant cystic neoplasms of the biliary ductal system accounting for a small portion of cystic lesions of the liver. While most cases are incidentally diagnosed on imaging, we present a unique case diagnosed via endoscopic retrograde cholangiopancreatography (ERCP) cholangioscopy (ERCP-C) finding a polypoid lesion within the bile duct and contrast retention within the cyst after ERCP-C.

Case Description/

Methods: A 59y/o woman with intermittent episodes of epigastric pain for years developed acholic stools and dark urine. There was mild biliary dilation on ultrasound. Initial ERCP found small choledocholithiasis. Subsequent MRI showed a 2.6cm cyst in segment (seg) 4b of the liver (present on prior US), mild left intrahepatic duct dilation with narrowing just proximal to the right hepatic duct with a poorly defined 1.5cm area noted. At that time, liver enzymes, CEA, and CA 19-9 were normal except mildly elevated alkaline phosphatase (123). Repeat ERCP-C was performed to rule out Klatskin tumor, revealing a 7mm polypoid lesion originating from the distal left main hepatic duct. Biopsies showed benign biliary type epithelium. Subsequent cholecystectomy with CBD exploration showed a 4cm polypoid lesion with the base in the left hepatic duct (LHD) and the free end prolapsing into the common hepatic duct (CHD), suggesting possible ball valve mechanism of biliary obstruction/injury. Pathology of the resection showed mucinous cystic neoplasm without evidence of high-grade dysplasia. Elevated CA 19-9 of 47.9 2 years later prompted an MRI showing doubling of size in seg 4b cystic lesion to 2.7x1.9cm. Repeat ERCP-C showed mild left biliary dilation and slightly delayed washout of contrast in seg 4b. Due to post-procedure pain, CT showed retained ERCP contrast in a 3cm cystic-solid mass, clearly indicating communication with the biliary tree. Left hepatic lobectomy was then performed with pathology showing a benign mucinous biliary cystadenoma of the liver with negative margins. Surveillance imaging over the following 2 years had no recurrence.

Discussion: Most biliary cystadenomas manifest in middle aged women as a multilocular cystic mass, usually without biliary ductal communication per WHO criteria. Literature review revealed this to be the first noted report of a mucinous biliary cystadenoma in the liver initially presenting as a polypoid lesion seen on ERCP-C or as retained contrast after ERCP. Careful workup and ERCP-C are key to diagnosis.

Disclosures:
Shyam Vedantam indicated no relevant financial relationships.
Alan Livingstone indicated no relevant financial relationships.
Jodie Barkin: AbbVie – Advisor or Review Panel Member. Aimmune Therapeutics – Advisor or Review Panel Member. Amgen – Consultant. CorEvitas – Consultant. Iterative Health – Consultant. Medtronic – Consultant. MotusGI – Consultant.

Shyam Vedantam, DO¹, Alan S. Livingstone, MD¹, Jodie A. Barkin, MD, FACG². P2334 - Polypoid Puzzle: A Hidden Mucinous Biliary Cystadenoma Revealed in a Novel Fashion by Spyglass and ERCP Contrast Retention With Literature Review, ACG 2025 Annual Scientific Meeting Abstracts. Phoenix, AZ: American College of Gastroenterology.