Case of the week Details

• Multiple asymmetric large dilated intrahepatic biliary ducts (blue arrow) noted with multiple varying-sized calculi (orange arrow) noted within the intrahepatic biliary radicles.
• The portal vein is seen traversing within the dilated ducts with multiple intraductal bridging septa seen traversing the dilated ducts, suggesting a central dot sign (green arrow).
• Associated dilatation of common bile duct ( 12mm) with few calculi in its distal aspect (orange arrow).
• Mild diffusion restriction along the wall of the bile ducts with few tiny diffusion-restricting foci noted in liver parenchyma – concerning for cholangitis (red arrow).

• Congenital disorders comprising of multifocal cystic dilatation of segmental intrahepatic bile ducts.
• Extrahepatic duct involvement may exist.
• They are also classified as a type V choledochal cyst, according to the Todani classification.
• Caroli disease is limited to the dilatation of larger intrahepatic bile ducts, whereas Caroli syndrome describes the combination of small bile ducts dilatation and congenital hepatic fibrosis.

Epidemiology

• Autosomal recessive disorders with a slight female predilection.

Clinical Features:

• Caroli disease presents with right upper quadrant pain, recurrent cholelithiasis, and cholangitis with fever and jaundice.
• Caroli syndrome presents with the previous symptoms along with signs of portal hypertension, including hematemesis and melena secondary to bleeding varices.

Pathology

• Belong to the spectrum of fibropolycystic liver disease which results from in utero malformation of the ductal plate.
• There is a high association with fibrocystic anomalies of the kidneys which share the same genetic defect (PKHD1 gene, chromosome region 6p21).
• The ductal plate is a layer of hepatic precursor cells that surround the portal venous branches and is the anlage of the intrahepatic bile ducts.
• The manifestation of ductal plate malformation depends on the level of the biliary tree that is affected.
• Thus, Caroli disease (the simple type) results from the abnormal development of the large bile ducts.
• In contrast, in Caroli syndrome (the periportal type of Caroli disease), both the central intrahepatic bile ducts and the ductal plates of the smaller peripheral bile ducts are affected, with the latter leading to the development of fibrosis.
• At the other end of the fibro polycystic disease spectrum are von Meyenburg complexes, also known as biliary hamartomas which result from discrete foci of ductal plate malformation affecting the smallest bile ducts.

Associations

• Congenital hepatic fibrosis.
• Medullary sponge kidney.
• Autosomal dominant polycystic kidney disease (ADPKD).
• Autosomal recessive polycystic kidney disease (ARPKD).

Radiographic features

• The disease may be diffuse, lobar or segmental.
• Dilatation is most frequently saccular rather than fusiform, a feature that might help in the differential diagnosis.

Ultrasound

• May show dilated intrahepatic bile ducts (IHBD)
• Intraductal bridging: echogenic septa traversing the dilated bile duct lumen
• Small portal venous branches partially or completely surrounded by dilated bile ducts .
• The intraluminal portal vein sign: dilated ducts surrounding the portal vein.
• Intraductal calculi.

CT

• Multiple hypodense rounded areas which are inseparable from the dilated intrahepatic bile ducts
• “central dot” sign: enhancing dots within the dilated intrahepatic bile ducts, representing portal radicles.

MRI

• T1: hypointense dilatation of IHBD
• T2: hyperintense.
• T1 C+ (Gd): enhancement of the central portal radicles within the dilated IHBR.
• MRCP: demonstrates continuity with the biliary tree

Nuclear medicine

• Intrahepatic bile ducts can have a beaded appearance on HIDA scans.

Complications

Simple type  

• Intrahepatic stone formation
• Recurrent cholangitis that may lead to bacteremia and sepsis
• Hepatic abscesses

Periportal fibrosis type

• Cirrhosis and portal hypertension
• Hepatomegaly
• Ascites
• Varices

There is an increased risk of cholangiocarcinoma, which develops in 7% of patients

Treatment and prognosis

• Prognosis is generally poor.
• If the disease is localized, segmentectomy or lobectomy may be offered.
• In diffuse disease management is generally with conservative measures; liver transplantation may be an option

Differential diagnosis

Polycystic liver disease 

1. No associated biliary duct dilatation.
2. Rarely communicate with the biliary ducts.

Peribiliary cysts.

Choledochal cyst.

Biliary hamartomas

• May be cystic

Primary sclerosing cholangitis

• Dilatation typically more fusiform and isolated;
• Associated inflammatory bowel diseasein 70% of Caucasian patients

Recurrent pyogenic cholangitis

• Both present with sepsis and biliary dilatation
• Saccular (vs fusiform) dilatation favours Caroli disease.

Obstructive biliary dilatation

REFERENCES

1.Federle MP, Jeffrey RB, Woodward PJ et-al. Diagnostic Imaging: Abdomen, Published by Amirsys®. Lippincott Williams & Wilkins. (2009) ISBN:1931884714. Read it at Google Books – Find it at Amazon.

2.Levy AD, Rohrmann CA, Murakata LA et-al. Caroli’s disease: radiologic spectrum with pathologic correlation. AJR Am J Roentgenol. 2002;179 (4): 1053-7. AJR Am J Roentgenol (full text) – Pubmed citation.

3.Fulcher AS, Turner MA, Sanyal AJ. Case 38: Caroli disease and renal tubular ectasia. Radiology. 2001;220 (3): 7203. doi:10.1148/radiol.2203000825 – Pubmed citation.

4.Desmet VJ. Ludwig symposium on biliary disorders–part I. Pathogenesis of ductal plate abnormalities. Mayo Clin. Proc. 1998;73 (1): 80-9. doi:10.4065/73.1.80 – Pubmed citation.

5.Rodés J, Benhamou J, Rizzetto M. Textbook of hepatology, from basic science to clinical practice. Wiley-Blackwell. (2007) ISBN:1405127414. Read it at Google Books – Find it at Amazon.

6.Kanne JP, Rohrmann CA, Lichtenstein JE. Eponyms in radiology of the digestive tract: historical perspectives and imaging appearances. Part 2. Liver, biliary system, pancreas, peritoneum, and systemic disease. Radiographics. 2006;26 (2): 465-80. doi:10.1148/rg.262055130 – Pubmed citation.

Dr. Jai Shilpa
Consultant Radiologist.
Manipal Hospital Radiology Group (MHRG)
Manipal Hospital, Bengaluru.

Dr. Srinivas P
Fellow in Radiology
Manipal Hospital Radiology Group (MHRG)
Manipal Hospital, Bengaluru.