Choledochal Cyst: Facts and Exceptions
The statement that the incidence of choledochal cyst is 1:1,000 is false. The actual prevalence varies from 1:100,000 in Western countries to 1:13,000 in Japan.
Epidemiology and Demographics
- Choledochal cysts are congenital malformations of the biliary system with significantly higher prevalence in Asian populations compared to Western countries 1
- They are 3-8 times more common in females than males, which is accurate 2
- The condition has a skewed distribution with hereditary features that is far more common in East Asian females 3
Pathophysiology and Association with PBMU
90% of patients do have an anomalous pancreaticobiliary duct junction (PBMU), with the pancreatic duct joining the common bile duct >1 cm proximal to the ampulla 4, 5
- This anomalous junction allows reflux of pancreatic enzymes into the biliary tree, contributing to inflammation and potential malignant transformation 4, 2
- PBMU is considered an independent disease entity from choledochal cyst but is strongly associated with it 4
Definition and Classification
- Choledochal cysts are correctly defined as congenital cystic dilations of the intrahepatic and/or extrahepatic biliary tree 2
- They are classified according to the Todani classification based on location, shape, and multiplicity 1
- Type I (solitary, extrahepatic) and Type IV (intra- plus extrahepatic) bile duct cysts have the greatest predisposition to malignancy 6
Clinical Presentation and Complications
- Patients may present with jaundice (84-90%), weight loss (35%), abdominal pain (30%), nausea and vomiting (12-25%), and fever (10%) 1
- Many patients are asymptomatic and diagnosed incidentally 1
- Complications include abdominal pain, jaundice, cystolithiasis, cholecystitis, pancreatitis, liver abscess, liver cirrhosis, and malignant transformation (3-7.5%) 2
Diagnostic Approach
- Contrast-enhanced MRI with magnetic resonance cholangiopancreatography (MRCP) is superior for accurate assessment of biliary obstruction 1, 7
- Ultrasound is often the first imaging modality but has limitations in fully characterizing the cyst 1
Management
- Complete excision of the choledochal cyst with Roux-en-Y hepaticojejunostomy is the treatment of choice 1, 7
- This approach is recommended to prevent potential malignant transformation and recurrent complications 1, 2
- For Type 4 cysts, complete excision of the extrahepatic component with Roux-en-Y hepaticojejunostomy plus extended hepatectomy may be necessary 7
Prognosis and Follow-up
- 5-year overall survival after choledochal cyst excision is 95.5% 2
- Patients require long-term follow-up after resection due to the risk of metachronous cancer 1, 7
- Recommended surveillance includes liver function tests and CA19-9 annually for 20 years (then biannually) 1
- Ultrasound should be performed biannually for 20 years (then every 3 years) 1