Definition:

Fluid-filled closed cavity lined by benign epithelium.

LI-RADS Categorization:

• Observations thought to definitely represent cysts should be categorized LR-1.
• e.g., cysts with typical imaging features and large enough to characterize.
• Observations thought to probably represent cysts should be categorized LR-2.
• e.g., cysts with mildly atypical features or low density lesions too small to characterize at CT.
• Observations that are indeterminate for cysts versus HCC should be categorized LR-3 or LR-4.

Comments:

• Most cysts are easily recognized, cause no diagnostic confusion, and do not require reporting. Radiologists may choose at their discretion to report cyst(s).
• The two most common cysts in the liver are hepatic cysts and cystic biliary hamartomas. Peribiliary cysts are rare cysts associated with advanced cirrhosis. In cirrhosis, they represent cystic dilatation of the extramural glands in the periductal connective tissue. They parallel the bile ducts; they may be misinterpreted as dilated bile ducts. Hepatic cysts, cystic biliary hamartomas, and peribiliary cysts do not communicate with the bile ducts.