Benign:
Simple cyst:
asymptomatic; thin, imperceptible homogeneous wall; unilocular; nonenhancing; not causing biliary obstruction or communicating with biliary system; anechoic on US and/or low-density fluid (< 20 HU) on CT and/or fluid signal on MRI. No further imaging follow-up recommended.
or
Benign, complicated cyst:
asymptomatic; hemorrhagic/proteinaceous cyst +/- calcification +/- thin septations AND nonenhancing; not causing biliary obstruction or communicating with biliary system. No further imaging follow-up recommended.
Probably benign:
Probably benign, complicated cyst:
asymptomatic; equivocally enhancing; thin, regular, possibly enhancing wall; few possibly enhancing septations; no mural nodularity. Consider follow-up US, CT or MRI liver in 6 to 12 months for 2 years, and/or Surgery referral.
Suspicious:
Neoplastic, complicated cyst:
thick, irregular, enhancing wall; multiple enhancing septations; multilocular; mural nodularity. Surgery referral is recommended.
or
Infectious, complicated cyst:
clinical history and signs of infection; peripheral rim enhancement; surrounding edema or inflammation; “cluster of grapes” sign; “double target” sign; large unilocular or multilocular cysts +/- crescentic mural calcifications; multiseptated with daughter cysts. Clinical correlation is recommended.
Frequently Asked Questions
What are hepatic cysts and how are they detected?
Hepatic cysts are fluid-filled sacs found in the liver. They are often detected through imaging techniques such as ultrasound (US), computed tomography (CT), or magnetic resonance imaging (MRI). Simple cysts appear as anechoic on US, low-density fluid (< 20 HU) on CT, or fluid signal on MRI. They usually have thin, imperceptible walls and do not enhance after contrast injection.
Are hepatic cysts dangerous?
Most hepatic cysts are benign and asymptomatic, posing no danger. Simple cysts, which are the most common, typically do not require treatment or follow-up imaging. However, more complicated cysts may require monitoring or intervention if they show suspicious features, such as irregular walls or septations, which can indicate neoplasia or infection.
When should a hepatic cyst be followed up with additional imaging?
Follow-up imaging is considered for probably benign, complicated cysts that may have equivocally enhancing features or wall irregularities. These cysts are monitored with ultrasound, CT, or MRI over a period of 6 to 12 months for up to 2 years to ensure they do not develop concerning characteristics. Suspicious cysts, on the other hand, often require surgical evaluation.
What imaging signs indicate a suspicious hepatic cyst?
Suspicious hepatic cysts may have thick, irregular, enhancing walls, multiple enhancing septations, and mural nodularity, which can suggest a neoplastic nature. Infectious cysts might show peripheral rim enhancement, surrounding edema, or a 'cluster of grapes' appearance. These features often necessitate surgical referral or further clinical evaluation.
How are infectious hepatic cysts diagnosed?
Infectious hepatic cysts are diagnosed through a combination of imaging findings and clinical history. They may show peripheral rim enhancement, surrounding edema, and signs such as the 'cluster of grapes' or 'double target' sign on imaging. The presence of symptoms or a history of infection further supports the diagnosis. Clinical correlation is crucial for confirming the infectious nature.
Do all hepatic cysts require surgery?
Not all hepatic cysts require surgery. Simple, uncomplicated cysts typically do not need any intervention. Surgery is generally reserved for cysts that exhibit suspicious features, such as thickened, irregular walls or signs of infection, indicating potential malignancy or complications that could necessitate removal or further investigation.
What is the 'double target' sign in hepatic cyst imaging?
The 'double target' sign is an imaging feature sometimes seen in infectious hepatic cysts. It refers to a specific pattern on imaging, where the cyst appears as a target with multiple rings or layers. This sign, along with other indicators like peripheral rim enhancement and surrounding edema, can help differentiate infectious cysts from other types.