Liver Cyst

What are liver cysts?

Liver cysts are fluid-filled sacs that develop within the liver. In most cases, they are benign and asymptomatic, and are often discovered incidentally during imaging scans performed for other reasons. While they may vary in size and number, most liver cysts do not affect liver function and require no treatment.

There are several types of liver cysts, the most common being:

• Simple cysts — these are non-cancerous and typically contain clear fluid. They have thin walls, do not communicate with the bile ducts, and are usually harmless.

• Polycystic liver disease — a hereditary condition in which multiple cysts form throughout the liver. It is often associated with polycystic kidney disease and may be passed down through families.

• Hydatid cysts — caused by a parasitic infection (Echinococcus), these cysts are less common but potentially serious, requiring specific medical or surgical treatment.

• Cystic tumours or complex cysts — in rare cases, liver cysts may have solid components or irregular features that raise concern for cystic neoplasms, which warrant further investigation to rule out malignancy.

Generally, liver cysts are harmless and do not turn into cancer. However, it is important to consult your doctor if your liver cyst:

• Causes pain or discomfort
• Bleeds or gets infected
• Is not a simple cyst (is complex, septated, or has solid parts)
• May be a hydatid cyst or cystic tumour

What is a non-simple or complex cyst?

A non-simple liver cyst, also known as a complex liver cyst, refers to a cyst in the liver that does not have the characteristics of a simple cyst.

A simple liver cyst typically:

• Has thin, smooth walls
• Contains only clear, fluid-filled content
• Appears uniformly black (anechoic) on ultrasound
• Is usually benign and asymptomatic

In contrast, a complex or non-simple liver cyst may have:

• Thickened or irregular walls
• Internal septations (dividing walls within the cyst)
• Solid components or nodules
• Internal echoes or debris on ultrasound
• Sometimes, calcifications

These features raise concern because complex cysts may be caused by:

• Hemorrhagic cysts (bleeding into a simple cyst)
• Infected cysts (abscesses)
• Hydatid (parasitic) cysts
• Cystic neoplasms (e.g. cystadenomas or cystadenocarcinomas)
• Polycystic liver disease

Further imaging (like CT or MRI) and sometimes biopsy may be required to determine the exact cause. Most complex cysts are still benign, but some may need treatment or closer follow-up depending on the features and symptoms.

What causes liver cysts?

Liver cysts may develop due to a variety of underlying causes, depending on the type of cyst involved. In most cases, especially with simple cysts, the cause is not well defined and they are discovered incidentally during scans. Some cysts are congenital, while others result from genetic conditions, infections, or rare tumour-related changes. Identifying the underlying cause helps guide appropriate management and follow-up.

Common causes include:

• Developmental abnormalities — simple liver cysts are often thought to arise from small bile ducts that failed to develop normally during embryonic growth. These ducts may become sealed off and slowly fill with fluid, forming a cyst. This type of cyst is not linked to lifestyle factors or liver disease and is usually benign.

• Genetic conditions — Polycystic liver disease (PLD) is a hereditary disorder in which multiple cysts form throughout the liver. It is often associated with polycystic kidney disease and is inherited in an autosomal dominant pattern. Individuals with a family history may be at increased risk.

• Parasitic infection (hydatid disease) — caused by Echinococcus granulosus, this parasitic infection can lead to the formation of hydatid cysts in the liver. It is contracted through the ingestion of parasite eggs and is more common in regions where livestock farming is prevalent. Hydatid cysts can enlarge over time and may require both medical and surgical treatment.

• Cystic tumours — rarely, cysts in the liver may be due to cystic neoplasms such as biliary cystadenomas or cystadenocarcinomas. These require careful evaluation, as some may have malignant potential and need to be surgically removed.

• Cyst complications — occasionally, a simple cyst may become more complex due to internal bleeding, infection, or rupture. These secondary changes can alter the appearance of the cyst and lead to symptoms that warrant further medical attention.

What are the symptoms of liver cysts?

In most cases, liver cysts do not cause any symptoms and are discovered incidentally during imaging scans done for unrelated reasons. These cysts are usually small and do not interfere with liver function. However, when they grow larger or become complicated, they may begin to produce noticeable symptoms.

Possible symptoms include:

• Abdominal discomfort or pain — a dull ache or feeling of pressure in the upper right side of the abdomen is the most commonly reported symptom. This occurs when a cyst becomes large enough to press against surrounding organs or stretch the liver capsule.

• Abdominal fullness or bloating — some individuals may experience a sensation of fullness, particularly after eating small meals. This can result from the space-occupying effect of a large cyst.

• Nausea or early satiety — a large cyst may press on the stomach, leading to nausea or a reduced appetite.

• Palpable mass — in rare cases, especially when the cyst is significantly enlarged, a noticeable lump may be felt in the upper abdomen.

• Complications such as rupture, bleeding, or infection — though uncommon, these events can lead to sudden and more severe symptoms, including sharp abdominal pain, fever, or signs of internal bleeding. These require urgent medical attention.

Who is at risk of liver cysts in Singapore?

Liver cysts can occur in individuals of any age, but certain groups may have a higher likelihood of developing them. In Singapore, groups who may be at increased risk include:

• Adults over the age of 40 — simple liver cysts tend to become more noticeable with age, likely due to gradual enlargement or increased use of imaging in older adults. They are rarely seen in children.

• Individuals with a family history of polycystic disease — those with a genetic predisposition to polycystic liver disease (PLD) or autosomal dominant polycystic kidney disease (ADPKD) are more likely to develop multiple liver cysts.

• People from or with exposure to endemic regions for hydatid disease — although rare in Singapore, individuals who have lived in or travelled to regions where Echinococcus infection is more common (e.g. parts of the Middle East, South America, or Central Asia) may be at risk of developing hydatid liver cysts.

• Women — some studies suggest that simple liver cysts and PLD may be more common in women, possibly due to hormonal influences, although the exact reason remains unclear.

How are liver cysts diagnosed?

Liver cysts are typically diagnosed through imaging studies. Many patients discover they have a liver cyst by chance while performing unrelated scans or routine check-ups.

• Ultrasound scan — this is often the first-line imaging test. It is non-invasive, quick, and provides clear images of the liver. Simple cysts typically appear as well-defined, fluid-filled structures with thin walls.

• CT (Computed Tomography) scan — for larger or atypical cysts, a CT scan may be recommended to better define the cyst’s size, location, and internal features. This helps in distinguishing simple cysts from more complex or potentially concerning lesions.

• MRI (Magnetic Resonance Imaging) — MRI provides even more detailed images and is especially useful when a cyst has unusual features or if there is concern about a cystic tumour. It allows us to assess the internal structure of the cyst without exposure to radiation.

• Blood tests — in certain cases, we may carry out blood tests to evaluate liver function or check for signs of infection, inflammation, or tumour markers, especially if the cyst appears complex or symptomatic.

• Additional testing for suspected hydatid disease — if a parasitic cause is suspected based on history or imaging, we may arrange for specific blood tests and further evaluation.

What are the treatment options for liver cysts in Singapore?

Generally, the treatment is recommended based on the size, type, and symptoms of the liver cyst. While many cysts do not require intervention, some may benefit from drainage or surgical removal if they become symptomatic or show concerning features.

We offer the following treatment options:

• Monitoring with imaging — most simple liver cysts are benign and do not require treatment. If the cyst is small and asymptomatic, we recommend periodic follow-up scans to observe for changes in size or appearance.

• Image-guided aspiration — this involves using ultrasound or CT guidance to drain the fluid from the cyst using a fine needle. It may provide temporary relief from symptoms, but recurrence is common as the fluid tends to reaccumulate.

• Treatment for complex or parasitic cysts — if the cyst has suspicious features or is caused by a parasitic infection (such as a hydatid cyst), further treatment such as antiparasitic medication or more extensive surgery may be required. We ensure all necessary investigations are completed before proceeding.

• Liver Cyst Keyhole Surgery (Laparoscopic Marsupialisation of Liver Cysts) — a minimally invasive, laparoscopic procedure for symptomatic or large simple hepatic cysts. Part of the cyst wall is removed to allow continuous drainage. This approach is effective in preventing recurrence and reaccumulation of fluid, and offers faster recovery with minimal scarring.

Summary

Although liver cysts are generally harmless and can often go undetected, it’s best to have it checked if you experience unexplained abdominal symptoms, such as discomfort, bloating or abdominal pain. Schedule a consultation with us for a thorough evaluation and personalised management plan. ​