S4544 Lemmel Syndrome Unveiled: A Rare Case of Periampullary Diverticulum-Induced Biliary Obstruction

Introduction: Lemmel syndrome is an uncommon cause of obstructive jaundice, characterized by extrinsic compression of the common bile duct (CBD) by a periampullary duodenal diverticulum in the absence of choledocholithiasis or neoplasia. Due to its rarity and nonspecific clinical presentation, it is often misdiagnosed, leading to delays in appropriate management. Endoscopic retrograde cholangiopancreatography (ERCP) serves both diagnostic and therapeutic roles. Case Description/Methods: Sixty-nine-year-old woman with history for supraventricular tachycardia and basal ganglia stroke presented with acute epigastric pain radiating to the right upper quadrant, accompanied by nausea and non-hemorrhagic vomiting. Laboratory investigations revealed elevated lipase (>3,000 U/L), amylase (>2,000 U/L), total bilirubin (1.5 mg/dL), alkaline phosphatase (156 U/L), aspartate aminotransferase (607 U/L), and alanine transaminase (516 U/L), along with leukocytosis and acute kidney injury. Abdominal computed tomography scan indicated acute pancreatitis, gallbladder wall thickening, and a duodenal diverticulum. Ultrasound showed a mildly dilated CBD without cholelithiasis. Magnetic resonance cholangiopancreatography (MRCP) demonstrated mild intra- and extrahepatic biliary dilatation and a large periampullary diverticulum, raising suspicion for Lemmel syndrome. During endoscopic retrograde cholangiopancreatography (ERCP), the major papilla was located at the edge of the diverticulum with redundant duodenal mucosa. Pancreatogram revealed a dilated pancreatic duct; a 5 Fr × 9 cm pancreatic stent was placed. Initial attempts at biliary cannulation were unsuccessful, necessitating EUS-guided cholangiography via a 22-gauge FNA needle, which showed a prominent bile duct with distal kinking likely due to the diverticulum. Subsequent needle-knife papillotomy allowed successful biliary access, and a 10 mm × 6 cm fully covered metal biliary stent was deployed. Discussion: This case underscores the diagnostic challenge posed by Lemmel syndrome, a rare entity resulting from periampullary diverticulum-induced biliary obstruction. The patient's presentation with pancreatitis and biliary obstruction without evident choledocholithiasis highlights the importance of considering Lemmel syndrome in differential diagnoses. Advanced imaging techniques, particularly MRCP and EUS, were instrumental in identifying the periampullary diverticulum and assessing its impact on biliary anatomy. The therapeutic approach involved a combination of ERCP and EUS-guided interventions, demonstrating the utility of a multidisciplinary endoscopic strategy in managing complex biliary obstructions.