What are the Todani classification types of choledochal cysts and the recommended management for each type?

Todani Classification of Choledochal Cysts and Management

Complete surgical excision with Roux-en-Y hepaticojejunostomy is the definitive treatment for most choledochal cysts (Types I, II, and IV) to prevent malignant transformation, while Type V (Caroli disease) requires individualized management ranging from surveillance to liver transplantation. 1, 2

Classification System

The Todani classification categorizes choledochal cysts based on anatomic location, shape, and extent of biliary involvement:

Type I: Extrahepatic Bile Duct Cysts

• Most common type, representing approximately 67% of all cases 3, 4
• Characterized by fusiform or saccular dilatation of the extrahepatic bile duct 5
• Carries significant malignancy risk (7.0% incidence of cholangiocarcinoma) 1

Type II: Diverticulum of Extrahepatic Bile Duct

• Rare variant presenting as a true diverticulum arising from the extrahepatic bile duct 3
• Represents approximately 2% of cases 3

Type III: Choledochocele

• Cystic dilatation of the intraduodenal portion of the common bile duct 5
• Located at the ampulla of Vater 5

Type IV: Multiple Cysts

• Type IVA: Combined intrahepatic and extrahepatic cysts 3, 5
• Type IVB: Multiple extrahepatic cysts only 5
• Type IVA has the greatest predisposition to malignancy along with Type I 1

Type V: Caroli Disease

• Isolated intrahepatic bile duct dilatation without extrahepatic involvement 6, 7
• Characterized by segmental saccular or fusiform dilatation of intrahepatic bile ducts 7
• Must be distinguished from Caroli syndrome, which includes congenital hepatic fibrosis and renal cystic disease 6, 7

Management by Type

Types I, II, and IV: Complete Surgical Excision

Primary surgical approach:

• Complete cyst excision with cholecystectomy 1, 2, 3
• Roux-en-Y hepaticojejunostomy for biliary-enteric reconstruction 1, 2, 3
• For Type IVA with intrahepatic involvement: hepaticoenterostomy at the porta hepatis with partial resection of intrahepatic cyst wall 1
• Liver resection may be added for localized intrahepatic disease 4

Critical timing considerations:

• Stabilize acute complications (cholangitis, sepsis) with antibiotics before definitive surgery 1
• Third-generation cephalosporins, ureidopenicillins, carbapenems, or fluoroquinolones for septic patients 1
• Urgent biliary decompression with ERCP-guided stenting within 24 hours if septic shock or antibiotic failure occurs 1
• For biliary obstruction without sepsis: ERCP with sphincterotomy and temporary plastic stent as bridge to surgery 1

Surgical outcomes:

• 5-year overall survival after excision is 95.5% 5
• Perioperative morbidity rate approximately 44%, most commonly wound infection (19%) 3
• No perioperative mortality in contemporary series 3

Type III: Endoscopic or Surgical Management

• Endoscopic sphincterotomy may be sufficient for small choledochoceles 5
• Surgical excision reserved for larger lesions or those with complications 5

Type V (Caroli Disease): Surveillance and Selective Intervention

Diagnostic confirmation:

• MRCP with contrast-enhanced sequences is the preferred diagnostic modality 7
• Look for the pathognomonic "central dot sign" (fibrovascular bundles within dilated ducts) 6, 7
• Non-invasive liver stiffness measurement to assess for hepatic fibrosis and distinguish Caroli syndrome 7
• Avoid diagnostic ERCP due to increased infection risk 7

Medical management:

• Ursodeoxycholic acid improves quality of life but does not prolong survival 1
• Beta-blockers for primary variceal prophylaxis in Caroli syndrome with portal hypertension 7
• Endoscopic variceal ligation for bleeding control as needed 7

Surgical options:

• Hepatic resection for localized disease with recurrent cholangitis or liver abscess 6
• Liver transplantation for diffuse disease with end-stage complications 4
• Not indicated for isolated, asymptomatic disease 6

Post-Resection Surveillance Protocol

All patients require lifelong surveillance due to persistent malignancy risk:

• Years 1-20 post-resection: 1

  • Liver function tests and CA19-9 annually 1
  • Ultrasound biannually 1
  • Annual MRCP for Caroli disease/syndrome 7

• After 20 years: 1

  • Liver function tests and CA19-9 biannually 1
  • Ultrasound every 3 years 1

• Median incidence of metachronous malignancy is 5.6% (range 0.7-40%) after resection 2

• Cholangiocarcinoma prevalence in Caroli disease is 7%, compared to 0.05% in general population 7

Critical Pitfalls to Avoid

Preoperative errors:

• Imaging frequently misdiagnoses cyst type; intraoperative findings may differ significantly 8
• MRCP is superior to CT for accurate biliary tree assessment 1
• Never use ERCP diagnostically when MRCP is available in Caroli disease due to infection risk 7

Surgical errors:

• Incomplete cyst excision leaves residual malignancy risk 1, 2
• Simple drainage or cyst-enteric anastomosis without excision is inadequate 2
• Primary choledochorraphy has higher stricture rates and doesn't eliminate malignancy risk 2

Follow-up errors:

• Malignancy risk persists even after complete excision, mandating lifelong surveillance 1, 2
• CA19-9 alone has poor diagnostic performance for cholangiocarcinoma screening in Caroli disease 7
• Anastomotic strictures occur in approximately 17% of patients and require long-term monitoring 4