Choledochal cyst is a congenital anomaly involving cystic dilation of the bile ducts. It is classified into 5 types based on the location and extent of dilation. Type I is the most common. Imaging plays an important role in diagnosis and classification, with MRCP being the gold standard. Treatment involves complete excision of the cyst and Roux-en-Y hepaticojejunostomy. Complications include stones, malignancy, cholangitis and rupture. Caroli's disease is a rare disorder involving saccular dilation of intrahepatic bile ducts.

1. Choledochal cyst
Dr Manmohan Bir Shrestha
For RADIOLOGY

2. Objectives
Introduction
Biliary tree anatomy
Classification
Etiology
Clinical presentation
Laboratory investigations
Imaging modalities
Prenatal diagnosis
Caroli’s disease
Differentials
Treatment
Complications

3. Choledochal cyst
• Congenital anomaly involving cystic dilation of various ducts of the
biliary tract.

4. Epidemiology
• Incidence
• Western population-
1 in 100,000 to 150000 live births
• More common in Asia
• 1 in 1000 live births in Japan
• Sex prevalence
Female dominance-
• 3-4:1

5. Biliary tree anatomy
Intrahepatic
Ductular and canalicular network of the acini
Interlobular ducts
Septal bile ducts
RHD & LHD
Extrahepatic
RHD & LHD
CHD
Cystic duct & GB
CBD

6. Normal size of bile ducts
• CBD
• Adolescents & adults
• Upto 8mm
• Post cholecystectomy
• Upto 12 mm
• >60 years of age
• +1mm per decade
• Cystic duct
• Upto 1.8 mm
CHD at porta hepatis-
5 mm

7. Todani’s classification of choledochal cyst

8. Types
• I a- dilation of extrahepatic bile duct (entire)
• Ib- dilation of of extrahepatic bile duct (focal)
• Ic- dilation of CBD portion of extrahepatic bile duct
• II- diverticulum of the CBD
• III- cystic dilation of the distal intraduodenal CBD
• IVa-multiple cysts intrahepatically & extrahepatically
• IVb- multiple cysts extrahepatically
• V- single or multiple intrahepatic cysts without extrahepatic
duct dilation.

9. 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr
Type IV
Type V
Occurrence
Type I – 61 %
Type II – less common
Type III – less common
Type IV - 28.5 %
Type V – 4.6%.
Type I
Type II
& III

10. Types of union between CBD+MPD
• Normal junction (union inside duodenal
wall)
1) 2-10 mm short common channel with a
diameter of 3-5 mm(55-85%)
2) Separate entrances into
duodenum(42%)
3) 8-15 mm long common channel
• Abnormal junction (union outside
duodenal wall)
1) MPD inserting into CBD >15 MM
from entrance into duodenum
2) CBD entering into MPD

11. Etiology
• Weakness of the duct wall
• Pancreaticobiliary maljunction / Long common channel
o Proximal insertion of MPD into CBD or vice versa outside duodenal
wall producing
a long common channel (>15 mm)
o Reflux of pancreatic enzymes into CBD that causes damage to the
ductal wall and leads to cyst formation

12. Clinical presentation
• Triad of –
• Abdominal pain
• Jaundice
• Right upper quadrant palpable mass
Infantile form
• Present before 12 months of age
• Present with obstructive jaundice, acholic stools & hepatomegaly
• Signs of hepatic fibrosis may be present
Adult form
• Anytime after 12 months of age
• May present with fever, nausea, vomiting & jaundice.
• Undiagnosed cases may present with cholelithiasis.

13. Laboratory investigations
• Increased bilirubin
• Increased alkaline phosphatase

14. Histopathology
• Ducts are thickened (connective tissue+smooth muscle strands)
• Inflammatory reaction increases with age, may lead to ulceration in
mucosa & submucosa
• May lack a typical biliary mucosal lining
• Repeated destruction and regrowth causes epithelial metaplasia
• High risk of adenocarcinoma

15. Imaging modalities
• USG
• CT Scan
• CT cholangiography
• MRI
• MRCP
• ERCP
• PTC
• HIDA Scan

16. Objectives of imaging
• To classify
• Mention extension
• To visualize pancreaticobiliary junction
• To rule out association with other diseases
• To search for associated complications
• To rule out differentials

17. USG
• Ballooned/fusiform cyst beneath porta hepatis separate from GB
• *Communication with bile duct needs to be demonstrated*
• Abrupt change of caliber at junction of dilated segment to normal
ducts
• Intrahepatic bile duct dilatation secondary to stenosis.

21. CT Scan
• Useful in identifying type IV & type V disease
• CT Cholangiography
• More sensitive for visualizing biliary tree
• More sensitive in detecting choledochal cysts
• Less sensitive to characterize pancreatic duct

24. MRI
• T1WI : hypointense dilatation of bile duct
• T2WI : hyperintense

25. T1WI

26. T2WI

27. Type III choledochal cyst in coronal T2WI

28. MRCP
• Gold standard for imaging choledochal cyst
• Administration of secretin increases pancreatic secretion and dilates
the pancreatic duct

30. Type II ( diverticulum) choledochal cyst arising from lateral wall of CBD

31. ERCP
• More useful in type III choledochal cyst to exclude periampullary
mass
Fusiform choledochal cyst with a long common channel
& stricture at pancreatico biliary junction

32. Percutaneous transhepatic cholangiogram(PTC)
Cholangiogram – Caroli’s disease with characteristic strictures
and segmental intrahepatic duct dilations.

33. HIDA Scan
• The normal scan provides functional & morphological information
about the hepatic parenchyma in the first 10min ( after inj. of
radionuclide), extrahepatic biliary tree by 20 min and excretion into
the bowel by 1 hour.
• Useful in demonstrating biliary peritonitis after choledochal cyst
rupture

34. Prenatal diagnosis
Ultrasound
Earliest diagnosis at 25 weeks
MRI

35. Ultrasound
D/D
1) Duodenal atresia
2) Cyst of
-ovary
-mesentery
-omentum
-pancreas
-liver

36. Caroli’s disease / Type V Choledochal cyst
• Rare congenital disease
• Autosomal recessive disorder
• Characterized by multifocal segmental saccular cystic dilatation of the
large intrahepatic bile ducts, which retain their communication with
the biliary tree
• May be diffuse / segmental / lobar

37. • Types
1)Simple form
2)Caroli’s syndrome
• associated with periportal hepatic fibrosis

38. Etiology-
Ductal plate malformation
?perinatal hepatic artery
occlusion
?hypoplasia/aplasia of
fibromuscular wall
components
Association-
Benign renal tubular ectasia
Medullary sponge kidney(80%)
Infantile polycystic kidney
disease
Congenital hepatic fibrosis

40. saccular dilatation of the
intrahepatic biliary ducts

42. Central dot sign
-enhancing fibrovascular bundle of
portal vein radicles completely
surrounded by dilated bile ducts

43. Multiple dilated intrahepatic ducts with tiny dots of contrast
representing portal radicles

44. D/D of Caroli’s disease
Polycystic liver disease
No associated biliary duct dilatation
Rarely communicate with biliary ducts
Biliary hamartomas
Cyst size < 5mm (generally)
Do not communicate with biliary tree
Primary sclerosing cholangitis
Dilatation more fusiform & isolated
Associated inflammatory bowel disease
Recurrent pyogenic cholangitis
Saccular dilatation favors Caroli’s disease
Obstructive biliary dilatation

45. Type I
Type II
Type III
Type IV
Type V

46. D/D of Choledochal cyst
• Duodenal diverticulum
• Pancreatic pseudocyst / cystic tumors
• Other causes of biliary tree dilatation

47. Causes of Biliary Obstruction
Benign miscellaneous
Choledocholithiasis
Haemobilia
Congenital biliary disease
 Choledochal Cyst
 Biliary Atresia
Infectious cholangitis
Sclerosing cholangitis
Neoplasms
Cholangiocarcinoma
GB carcinoma
Locally invasive tumors
Ampullary tumors
Metastases
Extrinsic compression
Mirizzi syndrome
Pancreatitis
Adenopathy

48. Treatment
• Type I & IV
• Cyst excision & hepaticojejunostomy to a Roux-en-Y limb
• Type II
• Simple cyst resection
• Type III
• Marsupialization of the cyst ,
usually through transduodenal approach
• Type V
• Segmental resection of liver if disease is localized
• Liver transplantation

49. Complications
• Stones in GB, CBD, within cyst, in MPD, in intrahepatic biliary tree
• Malignant transformation
• Recurrent pancreatitis
• Cholangitis/Cholecystitis
• Cyst rupture with bile peritonitis
• Bleeding
• Biliary cirrhosis + portal hypertension
• Portal vein thrombosis
• Hepatic abscess

50. References
• Textbook of Radiology & Imaging - David Sutton 7th Edition
• Diagnostic Ultrasound - Carol M. Rumack 4th Edition
• Radiology Review Manual - Wolfgang Dahnert 7th Edition
• Bailey & Love’s Short Practice of Surgery - 7th Edition
• Paediatric Surgery - Arnold G. Coran - 7th Edition