Question: A 79-year-old woman was admitted with a 2-day history of vomiting, malaise, and nocturnal yellowish stained cough. She denied having fever or pain. One month earlier she has had an episode of Escherichia coli pneumonia and sepsis. Her history included a cholecystectomy 9 months ago. Postoperatively, a benign bile duct stenosis had caused recurrent episodes of cholangitis and was treated by repeated endoscopic stenting. Furthermore, paroxysmal atrial fibrillation, coronary artery disease, and type 2 diabetes mellitus were present. On physical examination, she had slightly icteric sclerae and basal pulmonary rales. Laboratory results showed elevated alanine aminotransferase (160 U/L), aspartate aminotransferase (110 U/L), alkaline phosphatase 258 U/L, γ-glutamyl transferase (1514 U/L), and bilirubin (4.4 U/L). The leukocyte count was 15,000/μL. A sputum specimen was positive for Citrobacter freudii, E coli, and Enterococcus gallinarum. Blood culture was also positive for E coli. Chest radiograph showed a left-sided pulmonary infiltrate. Because the laboratory results suggested a cholangitis, endoscopic retrograde cholangiography was performed. The cholangiogram is illustrated in Figure A and shows an uncommon finding. What is the diagnosis? See the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI. A faint contrast joining between a biliary branch and the left sided pleura and bronchial tract was found (Figure B) giving rise to the diagnosis of a contralateral biliopulmonary fistula (BPF) caused by recurrent cholangitis. A schematic drawing highlights the findings (Figure C). The symptoms resolved after endoscopic stent insertion and targeted antibiotic treatment. Three months later, the patient again presented with pneumonia and cholangitis. At that time, a hepaticojejunosotomy was performed opeartively. Thereafter, she fully recovered and did not develop any further episodes of cholangitis or pneumonia during follow-up. A BPF describes an acquired communication between the biliary and pulmonary tract. Hydatid disease is the most common underlying condition. BPFs are also associated with hepatic abscess formation, biliary obstruction, surgery, or trauma. The treatment of choice is surgical resection, but percutaneous approaches and stent placement have also been used successfully.1Jamal Y. Tombazzi C. Waters B. et al.Bronchobiliary fistula in a cirrhotic patient: a case report and review of the literature.Am J Med Sci. 2008; 335: 315-319Crossref PubMed Scopus (10) Google Scholar Biliary obstruction leads to jaundice that is usually treated by endoscopic stent insertion. Biliary obstruction and endobiliary stents are predisposing factors for ascending cholangitis. Also, an increase in bile duct pressure can be observed. Recurrent or chronic cholangitis may lead to fistula formation. When penetrating the diaphragm, a biliary fistula can result in chemical pneumonitis and subsequent bacterial infection.2Csendes A. Kruse A. Funch-Jensen P. et al.Pressure measurements in the biliary and pancreatic duct systems in controls and in patients with gallstones, previous cholecystectomy, or common bile duct stones.Gastroenterology. 1979; 77: 1203-1210PubMed Scopus (158) Google Scholar BPFs are a rare entity, especially in the Western world, where hydatid disease is uncommon. Over a 32-year period, only 16 cases of BPF were reported by a French group.3Gugenheim J. Ciardullo M. Traynor O. et al.Bronchobiliary fistulas in adults.Ann Surg. 1988; 207: 90-94Crossref PubMed Scopus (91) Google Scholar Usually, they are located on the right side. Left-sided BPFs have been described anecdotally.1Jamal Y. Tombazzi C. Waters B. et al.Bronchobiliary fistula in a cirrhotic patient: a case report and review of the literature.Am J Med Sci. 2008; 335: 315-319Crossref PubMed Scopus (10) Google Scholar A contralateral fistula has not reported so far.