Choledochal cyst due to anomalous pancreatobiliary junction in the adult: sonographic findings

Background: Adult cases of choledochal cyst due to anomalous pancreaticobiliary duct junction have been rarely reported. At present, sonography (US) is the first tool for diagnosing biliary disorders. The aim of this study was to reevaluate the US findings of choledochal cysts due to anomalous pancreaticobiliary duct junction in adults. Methods: We reviewed the clinical manifestations and US findings of 12 such adult cases confirmed by endoscopic retrograde cholangiopancreatic ductography (ERCP). Patients were assigned to three groups: (a) associated with biliary carcinoma (two cases), (b) associated with choledocholithiasis (one case), and (c) not associated with other abdominal diseases (nine cases). Results: Patients in group c were asymptomatic, and the lesions were detected incidentally detected by US. In contrast, patients in group a sought medical care because of symptoms such as jaundice and those in group b sought medical attention because of abdominal pain. The diameter of a dilated bile duct on US was considerably less than that of ERCP (ERCP: 26–58 mm, mean = 37.6 mm; US: 13–32 mm, mean = 21.8 mm). Its diameter changed significantly under probe compression when the dilated bile duct took a purely cystic form but changed very little when it took a tubular form. Conclusion: Unlike cases in children, adult cases of choledochal cyst are generally asymptomatic. Careful US observation of the bile duct is thus expected to detect asymptomatic adult choledochal cysts cases. Cyst diameter can change significantly under probe compression, so it is important not to compress the bile duct during routine US examination.