Dilated common channel syndrome: endoscopic diagnosis, treatment, and relationship to choledochocele formation.

BACKGROUND: Choledochoceles (type III biliary cysts) are cystic dilations of the terminal common bile duct or common pancreatobiliary channel. Although no size criteria have been defined, it is generally assumed these must be large. However, we describe patients who do not meet the perceived size criteria for choledochoceles, but who nonetheless have a dilated common pancreatobiliary channel. METHODS: We reviewed the presenting symptoms, endoscopic and radiographic findings, and response to endoscopic therapy of patients meeting our criteria for the dilated common channel syndrome. RESULTS: Of 2847 patients undergoing ERCP, 100 (3.5%) had the dilated common channel syndrome. Common presenting symptoms and signs included abdominal pain in 97%, abnormal liver function test(s) in 66%, and a history of acute or recurrent pancreatitis in 46%. A bulge was visible above the papilla in 88%, with a dilated common bile duct in 54% and a dilated pancreatic duct in 28%. After endoscopic unroofing of the common channel, 77% had complete and long-lasting resolution of symptoms, 18% had partial or transient improvement, and 5% had no change. CONCLUSIONS: Although classic choledochoceles are rare, a lesser degree of dilation of the common channel is more frequent than generally appreciated. We postulate that this finding represents an "incomplete," acquired form of choledochocele, possibly caused by underlying papillary stenosis. Whatever the etiology and appropriate term, the presence of a dilated common channel predicts a high rate of clinical response to endoscopic therapy.