Caroli disease is a rare autosomal recessive disorder characterized by congenital segmental saccular dilatation of intrahepatic bile ducts. It arises from ductal plate malformation and is frequently associated with ARPKD (autosomal recessive polycystic kidney disease). Caroli syndrome defines the coexistence of Caroli disease + congenital hepatic fibrosis and is more common. Bile stasis increases the risk of recurrent cholangitis, intrahepatic stone formation, and cholangiocarcinoma development. The disease may be diffuse (entire liver) or segmental (typically left lobe).
Age Range
5-50
Peak Age
30
Gender
Equal
Prevalence
Rare
Caroli disease arises from a defect in embryonic ductal plate remodeling. During normal development, the ductal plate surrounding primitive hepatocytes transforms into mature bile ducts through apoptosis and remodeling. Disruption of this process results in segmental saccular dilatation of bile ducts. Within dilated ducts, portal vein branches (portal radicles) remain as islands — this is reflected in imaging as the 'central dot sign.' The portal radicle surrounded by the dilated bile duct appears as central dot-like enhancement and peripheral fluid density/signal on contrast-enhanced imaging. Bile stasis predisposes to bacterial colonization, causing recurrent cholangitis attacks and calcium bilirubinate stones. Chronic inflammation and bile stasis increase cholangiocarcinoma risk by 7-14%. In Caroli syndrome, congenital hepatic fibrosis is additionally present; this periportal fibrosis can lead to portal hypertension and esophageal variceal bleeding.
Central dot-like hyperdensity within dilated intrahepatic bile duct resulting from enhancement of the portal vein branch (portal radicle). Pathognomonic finding that distinguishes Caroli disease from other cystic liver diseases and simple biliary dilatation. Occurs because the bile duct surrounds the portal radicle during ductal plate malformation.
Central dot-like enhancement within dilated intrahepatic bile ducts on portal venous phase (central dot sign). This represents enhancement of the portal vein branch (portal radicle) that remains within the duct during saccular dilatation. The dot is surrounded by fluid-density dilated bile duct. Pathognomonic finding.
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Segmental saccular dilatation of intrahepatic bile ducts is noted with central dot-like enhancement within the dilated ducts on portal venous phase (central dot sign); findings are consistent with Caroli disease.
Segmental saccular dilatation of intrahepatic bile ducts on non-contrast CT — saccular (cyst-like) rather than fusiform dilatation. Dilated ducts are fluid density (0-15 HU). Hyperdense intrahepatic stones may be seen within the ducts. Dilatations may be diffuse or segmental (usually left lobe predominant).
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Segmental saccular dilatation of intrahepatic bile ducts with fluid density is noted, with hyperdense stones present within the canaliculi.
Saccular dilatations of intrahepatic bile ducts show markedly hyperintense signal on T2-weighted images. Dilated ducts demonstrate communication with peripheral bile ducts — an important distinguishing feature from simple hepatic cysts. Central dot sign appears as hypointense dot on T2 (flow void or fibrous portal structure).
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Hyperintense saccular dilatations of intrahepatic bile ducts are seen on T2-weighted series with hypointense central dots (central dot sign); consistent with Caroli disease.
MRCP clearly demonstrates saccular dilatations of intrahepatic bile ducts and their communication with each other and with normal-caliber bile ducts. Ducts form a 'grape cluster' or 'beaded' pattern. MRCP non-invasively maps the entire biliary tree anatomy providing critical information for surgical planning. The common bile duct is usually normal caliber (Todani type V).
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MRCP demonstrates saccular dilatations of intrahepatic bile ducts with communication to peripheral bile ducts; findings are consistent with Caroli disease (Todani type V).
Multiple anechoic/hypoechoic cystic structures within liver parenchyma communicating with each other and bile ducts on US. Linear echogenic septae representing portal vein branches ('bridging' or 'dot') may be seen within cystic structures — US equivalent of central dot sign. Intrahepatic stones appear as echogenic foci with posterior acoustic shadowing.
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Multiple cystic structures communicating with bile ducts are seen in liver parenchyma with echogenic septae within the cystic structures (US equivalent of central dot sign); suggestive of Caroli disease.
Color Doppler US detects venous flow within portal radicles inside dilated bile ducts. This finding confirms the central dot sign and proves that cystic structures are true bile duct dilatations (distinguishing from simple cysts). Spectral analysis shows typical portal venous waveform (hepatopetal, low velocity, phasic).
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Color Doppler US demonstrates portal venous flow within central structures inside dilated bile ducts; this finding confirms the central dot sign and is consistent with Caroli disease.
On T1-weighted images, intrahepatic stones show variable signal — calcium bilirubinate stones are typically T1 hypointense, while cholesterol stones may be hyperintense. Dilated bile ducts are T1 hypointense. Duct wall enhancement on contrast series is a finding favoring cholangitis/inflammation. Areas of hepatic fibrosis may show delayed phase enhancement (Caroli syndrome).
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Dilated intrahepatic bile ducts appear T1 hypointense with variable signal stones within the ducts and wall enhancement on contrast series.
Enhancement of dilated bile duct wall and periportal area in arterial phase — a finding suggesting active cholangitis. Wall enhancement is smooth and concentric, and should be differentiated from nodular/irregular enhancement seen in cholangiocarcinoma development. Perihepatic fluid, regional lymphadenopathy, and liver abscess may accompany.
Report Sentence
Enhancement of dilated bile duct wall is noted in the arterial phase, a finding consistent with active cholangitis.
Criteria
Only saccular dilatation of intrahepatic bile ducts without hepatic fibrosis. Todani type V. Rarer form (20%). Recurrent cholangitis and intrahepatic stones predominate. No portal hypertension findings.
Distinct Features
Liver parenchyma of normal morphology, no splenomegaly or varices, no portal hypertension findings. Bile duct dilatations are usually more prominent and widespread.
Criteria
Intrahepatic bile duct dilatation + congenital hepatic fibrosis coexistence. More common form (80%). Portal hypertension findings (splenomegaly, varices, ascites) accompany. Strong association with ARPKD.
Distinct Features
Delayed phase periportal fibrosis enhancement, splenomegaly, renovascular varices, fibrotic changes in hepatic parenchyma, bilateral large polycystic kidneys (in ARPKD association).
Criteria
Saccular dilatation limited to one hepatic segment or lobe. Most commonly affects left lobe (especially lateral segment). Segmental type can be treated with localized surgical resection (lobectomy/segmentectomy).
Distinct Features
Rest of liver is normal, prominent cystic dilatations in left lobe with compensatory right lobe hypertrophy, segmental atrophy may be seen.
Criteria
Widespread saccular dilatation involving both liver lobes. High risk of recurrent cholangitis, increased risk of cholangiocarcinoma development. Liver transplantation is the definitive treatment.
Distinct Features
Bilateral diffuse cystic dilatations, marked hepatomegaly, multiple intrahepatic stones, diffuse periportal fibrosis findings may be present.
Distinguishing Feature
Choledochal cyst primarily involves extrahepatic bile duct dilatation (Todani I-IV); Caroli disease shows intrahepatic saccular dilatation + central dot sign (Todani V). MRCP clearly differentiates biliary tree anatomy.
Distinguishing Feature
In recurrent pyogenic cholangitis, bile duct dilatation is acquired and segmental, stones are predominant, no central dot sign. In Caroli disease, congenital saccular dilatation + central dot sign are pathognomonic.
Distinguishing Feature
PSC shows multifocal strictures and intervening dilatations ('beaded appearance') of bile ducts; duct wall thickening and irregularity are prominent. Caroli has saccular dilatation + central dot sign, no strictures.
Distinguishing Feature
Biliary hamartomas (von Meyenburg complexes) are small (<15 mm), multiple cystic lesions without communication with bile ducts. In Caroli, dilatations are larger, saccular, and show communication with the biliary tree.
Distinguishing Feature
Biliary cystadenoma is a single, multilocular, septated cystic mass without communication with biliary tree. In Caroli disease, multiple saccular dilatations are in direct communication with the biliary tree.
Urgency
routineManagement
surveillanceBiopsy
Not NeededFollow-up
6-monthCaroli disease is a chronic condition requiring lifelong follow-up. Complications (recurrent cholangitis, intrahepatic stones) are managed with medical and endoscopic methods. In segmental type, lobectomy may be curative. In diffuse type, liver transplantation is the definitive treatment. Due to cholangiocarcinoma risk (7-14%), regular imaging follow-up (6-12 monthly CT or MRI) is recommended. CA 19-9 and CEA monitoring should be performed. In Caroli syndrome, portal hypertension complications (varices, ascites) must also be managed.
Caroli disease increases cholangiocarcinoma risk (7%). Recurrent cholangitis episodes are treated with antibiotics and drainage. Hepatic resection may be curative for localized disease. Liver transplantation is the last option for diffuse disease.