Correlating Endoscopic Findings With CT Coronal Findings to Discover a Choledochoduodenal Fistula From a Cholangiocarcinoma

Abstract

Introduction: Choledochoduodenal fistula (CDF) is one of the least common types of biliary enteric fistula. The most common causes of CDF are iatrogenic causes, gallstone disease and peptic ulcer disease. CDF secondary to cancer appears to be an exceedingly rare condition. We report a cholangiocarcinoma causing a CDF and highlight the importance of combining endoscopic findings with CT findings to make the diagnosis as well as the importance of reviewing both axial and coronal CT images. Case: A 57-year-old female with no significant medical history presents to the hospital with a 30-pound unintentional weight loss, mid-epigastric abdominal pain, worsening fatigue and anorexia. A CT was performed in the ED. Initially, only axial images were reviewed and demonstrated a large left liver lobe mass, pneumobilia and antral and duodenal thickening. Because of the nature of her symptoms and abnormal CT, an upper endoscopy was performed and demonstrated what appeared to be a fairly large duodenal bulb fistula. A review of the original CT scan's coronal sections clearly demonstrated a fistualizing tract from the duodenum to the left lobe of the liver as well what appeared to be extension of the tumor into the perihilar region. A CA-19-9 was 1000. The patient was referred to a tertiary care center with significant cholangiocarcinoma experience. Biopsy of the mass was consistent with cholangiocarcinoma. The patient was referred to oncology for further management: palliative chemotherapy versus hospice. Discussion: The differential diagnosis of choledochoduodenal fistula (CDF) includes iatrogenic causes, gallstone disease, and peptic ulcer disease. CDF secondary to cancers appear to be an extremely rare finding with only about ten cases reported in the literature. Here, we report another cancer causing a CDF-in this case a cholangiocarcinoma. This case highlights two key clinical points: the importance of combining endoscopy and radiologic imaging in making this rare diagnosis and the importance of reviewing both coronal and axial CT images in abdominal pathology cases. In our case, the findings on EGD led to further review of the original CT scan. The fistula that was difficult to appreciate in CT axial views was clearly appreciated in CT coronal views highlighting the importance of looking at both views.