What are Choledochoceles?
Choledochoceles are cystic dilatations of the intraduodenal portion of the common bile duct. They are often classified as Type III biliary cysts, but have distinct demographic and anatomic features, and a lower risk of malignancy than other types of choledochal cysts. In the February issue of Clinical Gastroenterology and Hepatology, Ryan Law and Mark Topazian discuss how they can be identified and treated.
Choledochoceles are typically diagnosed and managed by gastroenterologists. They are usually first observed as cystic lesions in the duodenum by computed tomography or magnetic resonance imaging. Further information is provided by endoscopic ultrasound or endoscopic retrograde cholangiopancreatography (ERCP), which can distinguish Type A and Type B choledochoceles from duodenal duplication cysts (see figure).
Choledochoceles are treated by endoscopic drainage or resection. They have a low risk of malignancy, compared with other types of biliary cysts, but should be evaluated histologically.
Patients with choledochoceles usually present with upper abdominal pain, nausea, and vomiting—different from other types of biliary cysts. Pancreatitis is the most common clinical complication associated with symptomatic choledochoceles and is frequently the event that leads to their identification. Patients often have acute relapsing pancreatitis with multiple discrete episodes due to obstruction of pancreaticobiliary outflow, which increases ductal pressure, or bile reflux into the pancreatic duct.
Choledochoceles and duodenal duplication cysts are usually benign, but some are malignant. The estimated incidence of carcinoma in symptomatic patients with choledochoceles has been estimated at 2.5%. This is in contrast to other types of choledochal cysts, which pose substantial risks for gallbladder carcinoma and cholangiocarcinoma.
Choledochal cysts are uncommon and prevalence varies with region—most are reported in Asia. Choledochoceles frequently develop in people of older age (average 51 years), compared with other choledochal cysts (average 29 years).
Law and Topazian propose that cystic lesions that arise from the intramural bile duct or intra-ampullary common channel, with direct anatomic communication to these ducts, be considered choledochoceles. These may be lined by biliary or enteric mucosa, but do not fuse with the duodenal wall and do not have a muscle layer other than muscularis mucosa.