Simple hepatic cyst
Simple hepatic cysts are common benign liver lesions and have no malignant potential.
There one of the commonest of liver lesions and occur in ~2-7% of the population 1-2. There may be a slight female predilection.
Hepatic cysts are typically discovered incidentally and almost always asymptomatic.
These lesions may be isolated or multiple and vary from a few millimeters to several centimeters in diameter. Simple hepatic cysts are benign developmental lesions that do not communicate with the biliary tree 2. The current theory regarding the origin of true hepatic cysts is that they originate from hamartomatous tissue. On histopathological analysis, true hepatic cysts contain serous fluid and are lined by a nearly imperceptible wall consisting of cuboidal epithelium, identical to that of bile ducts, and a thin underlying rim of fibrous stroma 2.
While they can occur anywhere in the liver, there may be greater predilection towards the right lobe of the liver 3 (Wonder why ? more liver tissue ?).
Certain diseases are associated with multiple hepatic cysts and include
- polycystic liver disease
- polycystic kidney disease: autosomal dominant polycystic kidney disease (ADPKD): hepatic cysts may be seen in ~40% of those with ADPKD 2.
- von Hippel lindau disease
General imaging features
They are typically round or ovoid in shape and have well-defined margins
On CT, a hepatic cyst demonstrates homogenous hypoettenuation (water attenuation) with around 0-10 HU. The wall is usually imperceptible, and the cyst does not enhance after intravenous administration of contrast material
On MR imaging a hepatic cyst have signal characteristics iso-intense relative to water and does not enhance after administration of contrast. The cyst wall is very thin or even imperceptible 4.
Therefore signal characteristics are:
- T1: homogeneous very low signal intensity
- T2: increase in signal intensity
In instances of intracystic hemorrhage which is a rare complication in simple hepatic cysts, the signal intensity is high, with a fluid-fluid level, on both T1- and T2-weighted images when mixed blood products are present 2.
General imaging differential considerations include other cystic liver lesions, including:
- hepatic hydatid cyst(s)
- hepatic abscess(es)
- biliary cystadenoma(s)
- choledochal cyst: communicates with biliary tree
On CT and T2 MRI images also consider: