Double Common Bile Duct: An Uncommon Etiology of Gastrointestinal Cancer

Abstract

A double or accessory common bile duct (ACBD) is a rare congenital anomaly that arises from disturbances in recanalisation of the hepatic primordium with the accessory bile duct opening into a part of the upper gastrointestinal tract (stomach, duodenum, ductus pancreaticus or septum). A duplicated bile duct has the same mucosa histologically as a single bile duct, however, the opening of a duplicated bile duct lacks a sphincter. This results in a higher probability of calculus formation and retrograde flow of gut contents, predisposing patients to liver abscesses, pancreatitis, pancreatic cancer, gallbladder cancer, gastric cancer, and ampullary cancer depending on the location of the opening of the ACBD. Our patient presented with crampy lower abdominal pain associated with an unintentional 40 pound weight loss over four months. Magnetic resonance imaging (MRI) of the abdomen with intravenous contrast demonstrated a 3.9cm heterogeneous solid pancreatic uncinate mass (see Fig. 1) with partial encasement of the superior mesenteric artery. There was no dilation of pancreatic duct. A type II ACBD (see Fig. 2 and Fig. 3) was also noted. Subsequent endoscopic ultrasound with fine needle aspiration of the uncinate mass demonstrated pathology consistent with pancreatic adenocarcinoma. He was eventually referred to a tertiary level center where he underwent chemoradiation. Treatment options vary depending on the presence of malignancy. In instances without gastric or pancreatic cancer but in the presence of unremitting symptoms, surgical resection of the ACBD is recommended to prevent the flow of bilious and pancreatic juices from creating a nidus of continuous inflammation that can progress to neoplastic changes.Figure: MRI of the abdomen with intravenous contrast showing a 3.9cm heterogeneous solid pancreatic uncinate mass.Figure: Choi classification of types of ACBD.Figure: MRI Abdomen showing type II ACBD.