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Year : 2000  |  Volume : 10  |  Issue : 3  |  Page : 173-174
"Central dot sign" on ultrasound - Diagnostic of Caroli's disease

Dept of Radiology, Rangaraya medical College, Govt. General Hosp, Kakinanda, AP, India

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Keywords: Caroli′s disease, ultrasound, central dot sign

How to cite this article:
Moorthy N, Venkata Ratnam I, Chandramohan P, Khan M, Rao R P. "Central dot sign" on ultrasound - Diagnostic of Caroli's disease. Indian J Radiol Imaging 2000;10:173-4

How to cite this URL:
Moorthy N, Venkata Ratnam I, Chandramohan P, Khan M, Rao R P. "Central dot sign" on ultrasound - Diagnostic of Caroli's disease. Indian J Radiol Imaging [serial online] 2000 [cited 2020 Sep 28];10:173-4. Available from:
Caroli's disease is a rare, congenital cystic dilatation involving intrahepatic bile ducts. The term Caroli's syndrome is used if the above anomaly is associated with congenital hepatic fibrosis. These entities belong to the group of hepatic fibropolycystic diseases, which are usually associated with renal polycystic disease. We report a case of Caroli's syndrome presenting as portal hypertension with medullary sponge kidneys. The classical "central dot sign" described on CT is well demonstrated easily on ultrasound. Awareness of this finding is highlighted.

   Case report Top

A five-years-old old boy was admitted with distension of abdomen for one month. He had mild hepatosplenomegaly. There was no icterus, hematemesis or malena. He had been hospitalized twice in the past with similar complaints. There was no significant family history. Blood tests revealed microcytic anemia and raised ESR. Liver function tests were normal. HbsAg was non-reactive. Renal parameters and the chest radiograph were normal. UGI endoscopy showed grade two esophageal varices.

Ultrasound showed mild hepatomegaly. There were multiple, cystic spaces of varying sizes, communicating with dilated intrahepatic biliary radicles. Some of these cystic or saccular spaces showed irregular echogenic linear strands traversing through them. No biliary calculi were seen. There was mild splenomegaly. Both kidneys showed focal, echogenic, medullary spaces with normal renal size. There was minimal ascitics. On color Doppler, the linear strands seen within the cysts exhibited vascular flow pattern. There were no varices. Liver biopsy showed hydropic degeneration and mononuclear cell collection in the portal area exhibiting piecemeal necrosis and fibrosis suggestive of biliary cystadenoma without stroma and associated chronic active hepatitis and bridging fibrosis.

   Discussion Top

Caroli's disease is characterized by congenital, segmental, nonobstructive, saccular dilatation of intrahepatic bile ducts without other hepatic abnormalities [1]. It was presumed to be autosomal recessive in character. Two forms of the disease have been described. The rare, so called pure form described by Jacqui Caroli is characterized by segmental saccular communicating intrahepatic bile duct dilatation, frequently present with stone formation, recurrent cholangitis and hepatic abscess. The liver involvement can be diffuse, lobar or segmental. It usually presents in childhood and about 75% of affected patients are boys. Cholangiocarcinoma can develop in 7% of patients. Caroli's syndrome is another form that is more common and is associated with congenital hepatic fibrosis [2]. The dilatation of intrahepatic biliary ducts in usually less prominent. Both the conditions result from malformation of the embryonic ductal plate at different levels of the biliary tree [3].

These patients present with features of portal hypertension. This ductal plate malformation of the interlobar bile ducts results in malformed and abnormally shaped branch bile ducts, around the portal tracts [4]. Some of the bile ducts contain bile. There is no inflammation or regeneration of nodules. Choledochal cysts may be associated. Portal hypertension is caused by hypoplasia or fibrous compression of portal vein radicles in the fibrous bands surrounding the nodules.

These dilated sacculi or cystic spaces appear as anechoic areas on ultrasound and are hypodense on CT. The fibrovascular bundles containing portal vein radicals and a branch of the hepatic artery bridging the saccule appears as a central dot or a linear structure on CT, enhancing with contrast. This "central dot sign" described on CT [5] can be easily seen on ultrasound as demonstrated in our case. Awareness of this finding on ultrasound can result in proper diagnosis and can avoid invasive tests for confirmation. The dilated cysts communicate with bile ducts. On color flow Doppler imaging, flow can be demonstrated within the linear strands [6]. Cholangiography shows diverticulum-like sacculi of intrahepatic bile ducts of varying sizes, shapes and distribution [7]. Calculi are common. The common bile duct is normal. Hepatic scintigraphy with 99 mTc diethyl IDA shows the typical "beaded" appearance of dilated intrahepatic bile ducts. In Caroli's syndrome both CT and ultrasound show focal mild dilatation of intrahepatic bile ducts (2-3 mm). The liver shows changes of portal hypertension (shrunken liver, splenomegaly, splenic and esophageal varices and ascitics). Intrahepatic biliary calculi are absent. Cholangiography shows typical findings of focal segmental dilatation. The MRCP findings in Caroli's disease are similar to ERCP [8].

Caroli's disease may be associated with choledochal cysts, medullary sponge kidney, infantile and adult polycystic kidney disease and cystic renal dysplasia. Cholangiocarcinoma may be a complication. Cirrhosis of liver mimics this condition and can be differentiated by biopsy where there will be hepatocellular dysfunction. Caroli's disease is sometimes included in the classification of choledochal cyst, which is not appropriate since choledochal cysts occur in extra hepatic bile ducts and there is no renal involvement.

   References Top

1.Caroli JR, Soupault J, Kossakowski L, Plocker M. Paradowska: la dilatation polykystique congenitale des voie biliares intraphepatiques. Semin Hop Paris 1958; 34: 488-495.   Back to cited text no. 1    
2.Summer field JA, Nagufuchi Y, Sherlock S, Cadafalch J, Scheuer PJ. Hepatobiliary fibropolycystic diseases. A clinical and histological review of 51 patients. J Hepatol 1986; 2: 141-156.   Back to cited text no. 2    
3.Sherlock, Sheila. Cystic diseases of the liver. In: Schiff's diseases of liver. 8th edition. Philadelphia: Lippincott-Raven, 1999; 1083-1089.   Back to cited text no. 3    
4.Desmet VJ. What is congenital hepatic fibrosis ? Histopathology 1992; 20: 465-477.   Back to cited text no. 4  [PUBMED]  
5.Choi BI, Yeon KM, Kim SH. Caroli disease: central dot sign in CT - Radiology 1990; 174: 161-163.   Back to cited text no. 5    
6.Gorka W, Lewall DB. Value of doppler sonography in the assessment of patients with Caroli's disease. J Clin Ultrasound 1998; 26: 283-287.   Back to cited text no. 6  [PUBMED]  [FULLTEXT]
7.William J Miller, Alan G Sechtin, William L Campbell, Philip C. Pieters Imaging findings in Caroli's disease. AJR 1995; 165: 333-337.   Back to cited text no. 7    
8.Asselah T, Ernst O Sergent G, L'hermine, c, paris JC Caroli's disease - A magnetic resonance cholangiopancreatography diagnosis Am J Gastroenterol 1998; 93: 109-110.  Back to cited text no. 8    

Correspondence Address:
NLN Moorthy
Dept of Radiology, Rangaraya medical College, Govt. General Hosp, Kakinanda, AP
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Source of Support: None, Conflict of Interest: None

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[Figure - 1], [Figure - 2], [Figure - 3]

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