Adenosquamous carcinoma of the common bile duct with choledochoduodenal fistula

Background: Choledochoduodenal fistula is an abnormal tract between the common bile duct and the duodenum. Common etiology includes iatrogenic instrumentation, choledocholithiasis, and duodenal ulcer. In rare cases, the fistula is a complication secondary to an occult malignancy such as biliary adenocarcinoma. Here we report a case with adenosquamous carcinoma of the common bile duct that causes a choledochoduodenal fistula. Case Report: A 72-year-old female patient presented with epigastralgia and poor appetite for 3 months. Upper gastrointestinal endoscopy showed an orifice with bile leakage in the posterior wall of the second portion of the duodenum. A biliodigestive fistula was noted. Endoscopic retrograde cholangiopancreatography ( ERCP) showed a choledochoduodenal fistula and a contrast filling defect in the distal common bile duct. Endoscopic transpapillary biopsy of the distal common bile duct revealed poorly differentiated adenocarcinoma. Pancreatoduodenectomy was performed by laparotomy. Pathological assessment revealed a moderately differentiated adenosquamous carcinoma of distal common bile duct. The patient's postoperative period was uneventful. Conclusion: For clinical evaluation of choledochoduodenal fistula of unknown etiology and if occult malignancy is suspected upper gastrointestinal endoscopy and ERCP should be done. Surgical resection is mandatory in choledochoduodenal fistulas with biliary cancer origin.