In Von Meyenburg complex (biliary hamartomas),
lesions are usually scattered,
multiple and can be solid,
cystic,
or mixed; "the starry sky” appearance is pathognomonic in Magnetic Resonance Cholangiopancreatography (Fig.
1,
Fig.
2). Hepatobiliary contrast agents will demonstrate no communication with the biliary tree.
At Ultrasound,
small hamartomas are usually echogenic.
Often tiny individual hamartomas cannot be resolved and are instead interpreted as diffuse heterogenous liver echotexture.
Larger hamartomas (>10 mm) may appear hypoechoic or anechoic and “comet tail artefact” may be seen [9].
Differential diagnosis from multiple liver metastases may be not simple by using Ultrasound,
so it could be necessary to use another technique (MR,
CT or even CEUS) to provide differential diagnosis of these conditions (metastases present more variable size and prominent enhancement),
as well as with the clinical history of the patient.
Congenital hepatic fibrosis is usually associated with autosomal recessive polycystic kidney disease [10].
It is characterized by enlargement of portal spaces due to the presence of fibrosis and numerous,
more or less ectatic,
abnormal bile ducts communicating with the biliary tree [11].
The main feature of the disease is portal hypertension without liver insufficiency,
but progression of fibrosis can evolve to true cirrhosis [12].
Morphologic changes in the liver with hypertrophy of the lateral segments of the left lobe and normal volume or hypertrophy of segments IVa and IVb (Fig.
3),
associated ductal plate malformations,
signs of portal hypertension,
such as varices,
splenomegaly,
and renal abnormalities,
are frequently found in combination in patients with congenital hepatic fibrosis [12].
Caroli disease is a rare autosomal recessive disease characterized by segmental or diffuse communicating,
non-obstructive,
saccular or fusiform dilatation of large intrahepatic bile ducts (up to 5 cm).
The "central dot sign" is pathognomonic (Fig.
5) and represents cystic enveloping of portal tract vessels [2].
Liver specific hepatobiliary MRI contrast agents can be useful to prove communication with the biliary tree and provide differential diagnosis from hamartomas.
We refer to “Caroli syndrome” when Caroli disease and congenital hepatic fibrosis coexist: this condition is even more common than Caroli disease alone [13].
Perhaps,
the two conditions may represent different stages of the same disease [13].
Choledochal cysts are predisposing factors for cholangitis,
pancreatitis,
and malignancy.
The use of hepatobiliary contrast agents will show a communication with the biliary tree.
They are classified according to the Todani modification of the Alonso- Lej classification (Fig.
8).
Although the cause is unclear,
it is widely accepted that choledochal cysts arise from an anomalous pancreaticobiliary ductal junction,
particularly a long common channel,
which is seen in 50–80% of patients [3,
4,
5].
Anomalous pancreaticobiliary ductal junction may allow mixture of pancreatic and biliary juices,
which activates pancreatic enzymes leading to consequent inflammation and weakening of the duct wall [3,
5].
In 22% of cases,
anomalous pancreaticobiliary ductal junction is seen without dilatation,
but patients are still at high risk of carcinogenesis,
particularly of gallbladder cancer [14].