Applied Radiology

Prepared by Peter Hrehorovich, MD, Ruwini de Silva, MD, and Suresh Maximin, MD, Department of Radiology, Sisters of Charity Medical Center, Staten Island, NY.

CASE SUMMARY

A 45-year-old man presented with a history of right upper quadrant pain. There was neither jaundice nor palpable abdominal mass. Laboratory values, including liver function tests, were within normal limits.

DIAGNOSIS

Adult presentation of a variation of a Todani type 1C choledochal cyst, specifically a fusiform dilatation with the additional complication of a degree of biliary obstruction from a stricture at the distal common bile duct.

IMAGING FINDINGS

Initial plain films of the abdomen showed no abnormality. The liver and spleen were normal in size.

An abdominal ultrasound disclosed multiple dependent foci within the gallbladder, suggesting tiny calculi or small foci of sludge (figure 1). There was mild-to-moderate central intrahepatic ductal dilatation with marked extrahepatic ductal dilatation out of proportion to that seen in the intrahepatic system. This suggested the possibility of a choledochal cyst rather than obstruction from a stone or a mass.

Contrast-enhanced computed tomography (CT) of the abdomen confirmed mild-to-moderate central intrahepatic biliary ductal dilatation (figure 2). There was also marked dilatation of the extrahepatic ductal system consistent with a choledochal cyst. The pancreas was unremarkable, and the remainder of the examination was within normal limits.

Hepatobiliary imaging with 7mCi Tc 99m mebrofenin administered intravenously revealed prompt excretion into a somewhat prominent intrahepatic biliary tree (figure 3). There was slight delay in gallbladder visualization, which occurred at 2 hours, ascribed to chronic cholecystitis. Ductal dilatation was consistent with separate intrahepatic and extrahepatic biliary ductal dilatation.

An endoscopic retrograde cholangiopancreatography (ERCP) (figure 4) confirmed the presence of a 6-cm area of fusiform dilatation involving the common bile duct with the cystic duct inserting directly into the cyst. Above this fusiform dilatation, there was a more uniform, generalized biliary ductal dilatation, suggesting that there may be a distal obstructive component. There was an anomalous union of the common bile duct and the pancreatic duct into a very long common channel with a stricture noted at the distal portion of the common bile duct, immediately following the termination of the choledochal cyst, and prior to the union with the pancreatic duct. Otherwise, the pancreatic duct was of normal caliber.

Cyst excision with Roux-en-Y hepaticojejunostomy was performed, and the patient recovered without complication. Pathology of the specimen was consistent with chronic inflammation, and revealed no evidence of malignancy. No gallstones were identifiable at pathology.

DISCUSSION

Choledochal cysts, cystic dilatation of the common bile duct, are an uncommon but potentially serious condition that has been reported throughout the world in various age groups. Reported cases have ranged in age from infancy to 80 years, with predominance in children and women. The pathogenesis of the cysts is a matter of considerable discussion. Babbit ¹ proposed the common channel theory. He postulated that an abnormal pancreaticobiliary duct junction allowed reflux of pancreatic secretions into the biliary system at a critical time of its formation, resulting in enzymatic destruction of the duct wall with consequent cystic dilatation. Alternative theories propose that these cysts form a part of a spectrum of embryonic malformations of the biliary and pancreatic duct systems. ¹ Regardless of the etiology, multiple abnormalities have been reported and classified. Todani's classification is a useful format for cataloging the reported cases. ²

Clinical presentation is often very nonspecific. Intermittent right upper quadrant discomfort is frequently the only symptom. The classic triad of abdominal pain, jaundice, and a right upper quadrant mass is reported in less than one third of the cases. Consequently, a high index of suspicion is required to recognize choledochal cysts when various imaging studies are ordered for patients presenting with vague abdominal complaints. ³ The present case report presents the sonographic, isotope, and CT findings demonstrating the presence of choledochal cysts. Endoscopic retrogradecholangiopancreatography provided the definite diagnosis in this reported case.

Choledochal cysts carry a risk for malignancy, cholelithiasis, pancreatitis, and liver abscesses. They are associated with portal hypertension due to cystic compression of the portal vein and may result in ascites. Bile peritonitis due to cyst rupture has also been reported. Consequently, once a definitive diagnosis has been established, surgical intervention is indicated. ⁴