Upper gastrointestinal bleeding secondary to choledochoduodenal fistula as a presentation of gallbladder adenocarcinoma.

We present the case of a 75-year-old woman who presented to our hospital with upper gastrointestinal bleeding and altered liver function tests. MR cholangiography performed during hospitalization revealed a choledochoduodenal fistula. Gastroscopy confirmed the presence of this fistula, and after surgical correction, an adenocarcinoma at the biliopancreatic junction infiltrating the duodenum was diagnosed. This represents a rare and unusual presentation of biliopancreatic tumors, with endoscopy playing a crucial role in diagnosis.