Case Report: An Unreported Presentation of Lemmel Syndrome Highlighting Diagnostic Challenges of Duodenal Masses.

We present a case involving a 67-year-old patient with a medical history of gastric bypass who was recently diagnosed with a 6-centimeter duodenal mass causing biliary duct stenosis. Despite our best efforts, we were unable to access this tumor endoscopically, necessitating surgical intervention. During the surgical exploration, we discovered a duodenal diverticulum filled with stones, leading to the obstruction of the biliary ductâ?"a manifestation of Lemmel syndrome. This rare condition is characterized by obstructive jaundice in the absence of choledocholithiasis or tumors and is secondary to dilatation of peri-ampullary diverticula. While it is typically managed through endoscopy, our diagnostic and therapeutic approach was complicated by the patient's history of bariatric surgery (gastric bypass), making endoscopic access impossible despite our multiple attempts. This case report sheds light on the challenges posed by the concurrence of a rare pathology and surgically modified anatomy, which is increasingly encountered in daily surgical practice. In such situations, exploratory surgery continues to play a significant role.