Diagnosis of bronchobiliary fistula by bilirubin crystallization in the alveolar lavage fluid: case reports and literature review.

Bronchobiliary fistula (BBF) refers to the abnormal traffic between the biliary tract and the bronchus. The condition is very rare and usually develops secondary to liver echinococcosis or amebiasis, liver abscess, trauma, biliary obstruction, or tumors. BBF has a high mortality rate and currently, there are no accurate and effective diagnostic methods. This study reports the diagnosis and treatment of two patients with BBF which were confirmed by detecting bilirubin crystallization in the sputum. The first patient was a 45-year-old woman admitted to the hospital with "recurrent cough and lung infection". She had a history of multiple biliary tract surgeries and bilirubin crystallization was detected in bronchoalveolar lavage fluid (BALF) upon examination. Computed tomography (CT) imaging and magnetic resonance cholangiopancreatography (MRCP), together with clinical features, confirmed a diagnosis of BBF. The second patient was a 53-year-old woman admitted to the hospital with coughing and bile-like sputum. She had a history of cholangiocarcinoma surgery and bilirubin crystallization was detected in the cytomorphological BALF examination. Endoscopic retrograde cholangiopancreatography (ERCP) combined with clinical features confirmed a diagnosis of BBF. Both patients recovered after treatment and were discharged from the hospital. The clinical diagnosis of BBF largely relies upon imaging combined with clinical standards, and BALF examinations are rarely performed. This current investigation retrospectively analyzed the diagnosis and treatment of two cases of BBF, and demonstrated that bilirubin crystallization in the BALF may be an important diagnostic indicator for BBF.