Image of the Month—Diagnosis FREE

Choledochocele is a rare type of choledochal cyst (type III according to Todani classifications¹) characterized by cystic dilatation of the bile duct terminal and protrusion of the papilla of Vater into the duodenal lumen.² This anomaly has a prevalence of 0.3% to 0.4% among endoscopic retrograde cholangiopancreatography recipients and 1% to 5% among choledochal cysts.³

Horaguchi et al² have proposed a practical classification of choledochoceles into 2 types. In type I, the bile duct terminal forms a choledochocele and opens to the duodenum independently from the pancreatic duct or forms a very short common channel with the pancreatic duct. In type II, the pancreatic duct opens to the choledochocele. Type II occurs in 10% of choledochoceles and represents an anomalous arrangement of the pancreatobiliary ductal systems.²

Choledochocele is an extremely rare entity in the medical literature. Edil et al,⁴ in the largest series of the western world for choledochal cysts, reported 4 cases of choledochocele in 92 patients. Singham et al,⁵ from Canada, in the second largest series reported 1 case in 51 patients. Choledochoceles usually remain asymptomatic or may cause symptoms similar to those of choledocholithiasis, such as intermittent upper abdominal pain and jaundice. The diagnosis is difficult and in asymptomatic cases can be missed even at cholecystectomy.⁶ Stones in the choledochocele or the bile duct may induce acute pancreatitis and cholangitis.

Preoperative diagnosis of choledochocele is mainly based on endoscopic ultrasonography, magnetic resonance cholangiopancreatography, and endoscopic retrograde cholangiopancreatography. In upper gastrointestinal endoscopy, choledochocele may appear similar to duodenal duplication cyst, papillitis, papillary neoplasm, or mucosal elevation because of inadvertent submucosal injection of water or contrast material during endoscopic retrograde cholangiopancreatography.^6- 7 Impacted gallstones at the papilla of Vater or cystic changes at the bile duct terminal after endoscopic sphincterectomy for lithiasis may mimic choledochocele.

Choledochocele can be accompanied by lithiasis due to endocystic cholestasis. In a collection of 85 cases from the world literature, Mascetti et al⁸ found lithiasis in 43%. Coexistent biliary malignancy in choledochocele, as described in the literature, is rare and occurs in 2.5% to 4% of cases. Choledochocele entails usually little risk of bile duct malignancy compared with the other types of choledochal cysts, as it is not associated with abnormal junction between the pancreatic and common bile ducts and the mucosal line is usually duodenal and not biliary.⁹ However, certain authors report higher rates of concomitant biliary malignancy. Horaguchi et al² reported 14.3% prevalence of coexisting malignancy in 21 patients.

The surgical management of type III cysts is less clear and controversial.^2,4 In asymptomatic patients, close observation for complications of lithiasis with or without ductal obstruction, pancreatitis, and possible malignancy is recommended. Endoscopic sphincteroplasty or unroofing of the cyst is usually an adequate treatment.⁴ Radical surgery, such as pancreaticoduodenectomy, is seldom necessary, only if there is a high suspicion for biliary malignancy.⁴ In symptomatic cases, with stones entrapped within the sac of choledochocele, as occurred in our patient, surgical exploration and stone extraction is recommended.^4,6

Our patient had a type I choledochocele, according to the Horaguchi et al classification,² as there was a very short common pancreatobiliary channel. She was symptomatic with lithiasis and inflammation and the surgical treatment was very effective.

Return to Quiz Case.