CHOLEDOCHAL CYSTS

1. CHOLEDOCHAL CYSTS Aswad Habeeb Hameed Al-Obeidy FICMS GE & Hep

2. CHOLEDOCHAL CYSTS • Congenital anomalies of the biliary tract that manifest as cystic dilatation of the extrahepatic and intrahepatic bile ducts • The incidence rate of choledochal cysts is 1 in 13,000 to 15,000 in Western countries and as high as 1 in 1000 in Japan • These cysts are not familial • Females are more commonly affected than males • Cases have been described in utero and in elderly patients • Approximately two thirds of patients come to medical attention before age 10 years

3. Classification • The classification proposed by Todani and colleagues • Several varieties of type I cysts, accounting for 80% to 90% of cases • Exhibit segmental or diffuse fusiform dilatation of the common bile duct • Ia, common type; Ib, segmental dilatation; Ic, diffuse dilatation • Type II cysts consist of a true choledochal diverticulum • Type III cysts consist of dilatation of the intraduodenal portion of the common bile duct, or choledochocele • Type IV cysts may be subdivided into type IVa, multiple intrahepatic and extrahepatic cysts, and type IVb, multiple extrahepatic cysts • V, or Caroli's disease, which consists of a single or multiple dilatations of the intrahepatic ductal system, should be viewed as a form of choledochal cyst is not settled

5. Etiology • The cause of choledochal cysts has not been established • Congenital weakness of the bile duct wall, a primary abnormality of epithelial proliferation during embryologic ductal development • Congenital obstruction of bile ducts have been suggested • A relationship to other obstructive cholangiopathies, such as biliary atresia, has been proposed but not proven • Reovirus RNA has been detected by reverse transcriptase–polymerase chain reaction methodology in hepatic or biliary tissues of 78% • A high frequency (40%) of an anomalous junction of the pancreatic and common bile ducts

6. Pathology • The cysts are composed of a fibrous wall • There may be no epithelial lining or a low columnar epithelium • Mild chronic inflammation may be present • Complete, in-flammatory obstruction of the terminal portion of the common bile duct is common in infants who have a choledochal cyst • Liver histology in the affected neonate shows typical features of large duct obstruction • Portal tract edema, bile ductular proliferation, and fibrosis may be prominent • A pattern of biliary cirrhosis may be observed in older patients with long-standing biliary obstruction • Carcinoma of the cyst wall may occur by adolescence

7. Clinical Features • Disease often appears during the first months of life • As many as 80% of patients have cholestatic jaundice and acholic stools • Vomiting, irritability, and failure to thrive may occur • Physical examination shows hepatomegaly and, in approximately one half of patients, a palpable abdominal mass • Spontaneous perforation of a choledochal cyst may occur • In older patients, epigastric pain, which may result from pancreatitis, is the most common symptom • Intermittent jaundice and fever may result from recurrent episodes of cholangitis • The classic triad, consisting of abdominal pain, jaundice, and a palpable abdominal mass, is observed in less than 20% of patients

8. Diagnosis • The diagnosis of a choledochal cyst is best established with ultrasonography • Several reports have demonstrated that antenatal ultrasonography can be used to detect a choledochal cyst in the fetus • Sequential ultrasonographic examinations have allowed study of the evolution of choledochal cysts during pregnancy • In the older child, percutaneous transhepatic cholangiography or ERCP may help define the anatomic features of the cyst • MRCP is being used increasingly to evaluate the extent of the cyst and defects within the biliary tree and to detect an anomalous junction of the pancreaticobiliary ducts • In practice, most pediatric surgeons rely on an operative cholangiogram to define the extent of intrahepatic and extrahepatic disease

9. Treatment • Preferred treatment for choledochal cyst is surgical excision of the cyst with reconstruction of the extrahepatic biliary tree • Biliary drainage is usually accomplished by a choledochojejunostomy with a Roux-en-Y anastomosis • Excision of the cyst reduces bile stasis and the risk of cholangitis and malignancy • Simple decompression and internal drainage should be done only when the complicated anatomic characteristics do not allow complete excision • Long-term follow-up is essential, because recurrent cholangitis, lithiasis, anastomotic stricture, and pancreatitis may develop years after the initial operation

10. Caroli's Disease • Caroli's disease is a subtype of choledochal cyst characterized by diffuse intrahepatic dilatation • Classically segmental and saccular and is associated with stone formation and recurrent bacterial cholangitis • May manifest as cholangitis, abscesses, jaundice, or cirrhosis • A more common type, Caroli's syndrome, is associated with a portal tract lesion typical of CHF • Renal disease occurs in both forms, renal tubular ectasia occurs with the simple form, and both conditions can be associated with autosomal recessive polycystic renal disease • The gene encodes a large protein (4074 amino acids), which has been called fibrocystin to reflect the main structural abnormalities in liver and kidney • The intrahepatic cysts are in continuity with the biliary tract and are lined by epithelium that may be ulcerated and hyperplastic • The cysts may contain inspissated bile, calculi, and purulent material

11. Caroli's Disease • During childhood and adolescence because of hepatomegaly and abdominal pain • The disorder appears in the neonate as renal disease or cholestasis • Stagnation of bile, leading to formation of biliary sludge and intraductal lithiasis • Fever and intermittent jaundice may occur during episodes of bacterial cholangitis • Hepatospleno-megaly is found in cases associated with CHF; affected patients may exhibit bleeding esophageal varices • Ultrasonography, MRC, and computed tomography are of great value Percutaneous or endoscopic cholangiography usually demonstrates a normal common duct with segmental, saccular dilatations of the intrahepatic bile ducts • Hepatic resection is indicated for disease limited to a single lobe • Therapy with ursodeoxycholic acid, 10 to 15 mg/kg/day in individual doses • Liver transplantation is an option in pati-ents who have extensive disease and frequent complications