S3302 Type III Mirizzi Syndrome: A Case of Diagnostic Challenge and Surgical Management

Introduction: Mirizzi syndrome is an uncommon cause of obstructive jaundice due to extrinsic compression of the common bile duct (CBD) by an impacted stone in the cystic duct or gallbladder infundibulum. Type III Mirizzi syndrome is rare, accounting for less than 0.1-0.5% of all cases of gallstone-related surgeries. Diagnosis can be inconclusive, often requiring multiple imaging modalities and invasive interventions. We present a case of type III Mirizzi syndrome requiring multiple endoscopic retrograde cholangiopancreatography (ERCP)s and surgical exploration for diagnosis and treatment. Case Description/Methods: A 65-year-old woman with a history of fatty liver presented with 2 weeks of epigastric pain, jaundice, pruritus, and decreased appetite. She was hemodynamically stable but icteric. Labs showed AST 111, ALT 207, ALP 459, total bilirubin 13.4, and direct bilirubin 11.36, consistent with a cholestatic pattern. Ultrasound revealed a dilated common bile duct (CBD). ERCP demonstrated CBD dilation with extrinsic compression, but no visible stones. A biliary sphincterotomy was performed. Persistent jaundice and elevated liver enzymes led to a magnetic resonance cholangiopancreatography (MRCP), which showed a filling defect at the cystic duct-CBD junction. A second ERCP with Spyglass cholangioscopy identified a large, impacted stone at the cystic duct origin, compressing the CBD. Electrohydraulic lithotripsy was performed, and multiple stone fragments were removed. Despite initial improvement, definitive diagnosis remained uncertain. The patient underwent surgical exploration by the hepatobiliary team. Intraoperative findings revealed an intrahepatic gallbladder with a large stone eroding into the bile duct wall, consistent with type III Mirizzi syndrome. A cholecystobiliary fistula and partial destruction of the CBD were identified. The bile duct was resected, and Roux-en-Y hepaticojejunostomy was performed. The patient recovered well and was discharged with follow-up. Discussion: This case highlights the diagnostic complexity of type III Mirizzi syndrome, a rare entity that is both clinically and radiographically challenging to diagnose. Initial ERCP and MRCP may be inconclusive. Advanced cholangioscopy and surgical exploration are often required. A multi-disciplinary approach must be considered for diagnosis and treatment.