Beyond the Tumour: Double Duct Sign Unveiling Silent Lemmel’s Syndrome

Abstract

Lemmel’s syndrome is a rare cause of obstructive biliary dilatation resulting from extrinsic compression of the distal common bile duct by a periampullary duodenal diverticulum, in the absence of gallstones or malignancy. We report a case of a 69-year-old male with an incidental finding of periampullary diverticulum on CT imaging during follow-up for a pulmonary nodule. Imaging revealed biliary and pancreatic duct dilatation without evidence of obstructing calculi or soft tissue mass. The patient remained asymptomatic with normal liver function tests throughout follow-up. This case highlights the importance of considering Lemmel’s syndrome as a differential diagnosis in both asymptomatic patients and those presenting with acute abdomen. Accurate recognition on imaging is essential to avoid misdiagnosis and unnecessary interventions.