A Rare Case of Ectopic Bile Duct in the Third Portion of the Duodenum.

Ectopic drainage of the common bile duct into the third portion of the duodenum is an extremely rare anatomical anomaly of the biliary tract, often overlooked due to its asymptomatic nature. Its diagnosis relies primarily on imaging, particularly MR cholangiography, which allows for accurate and non-invasive analysis of the biliary tree. Recognition of this variant is important, as it can lead to atypical clinical presentations and pose diagnostic and therapeutic challenges, particularly due to potential difficulties during endoscopic procedures such as endoscopic retrograde cholangiopancreatography (ERCP), linked to the unusual location of the biliary orifice. Here, we report a case of a patient with a prior cholecystectomy who presented with diffuse abdominal pain, without fever or abnormal laboratory findings. Initial ultrasound was normal, and MR cholangiography revealed an abnormal common bile duct orifice in the third portion of the duodenum. This case illustrates the value of imaging in identifying this rare variant and highlights the importance of its recognition, particularly to anticipate potential technical difficulties during endoscopic procedures.