Choledochal cyst

Choledochal cysts are congenital anomalies involving dilatation of the bile ducts. They are uncommon in the Western world but are not rare in East Asian countries. The cysts can cause significant morbidity and are a risk factor for biliary tract cancer.

Classification

The Todani classification system is used to categorize choledochal cysts. This system classifies the cysts into five types:

• Type I: This is the most common type and involves cystic dilatation of the common bile duct.
• Type II: This type is characterized by a diverticulum protruding from the bile duct.
• Type III: Also known as choledochoceles, these are cysts located in the duodenal wall.
• Type IV: This type involves multiple cysts in both the intrahepatic and extrahepatic bile ducts.
• Type V: Also known as Caroli's disease, this type involves cystic dilatation of the intrahepatic bile ducts only.

Symptoms

The classic triad of symptoms for choledochal cysts includes jaundice, right upper quadrant abdominal pain, and a palpable mass. However, this triad is only present in a minority of patients. Other symptoms can include nausea, vomiting, and weight loss.

Diagnosis

The diagnosis of choledochal cysts is typically made through imaging studies. Ultrasound is often the first imaging modality used, but magnetic resonance cholangiopancreatography (MRCP) is the most accurate.

Treatment

The treatment of choice for choledochal cysts is surgical removal of the cyst (cystectomy), followed by reconstruction of the bile ducts. This is typically done through a Roux-en-Y hepaticojejunostomy.

Prognosis

If left untreated, choledochal cysts can lead to serious complications, including cholangitis, pancreatitis, and biliary tract cancer. However, with appropriate treatment, the prognosis is generally good.