What Size of Liver Cyst is Dangerous? What You Need to Know

Liver cysts are fluid-filled sacs that form in the liver. Many people have them but don’t know it. However, it is important to recognize what size of liver cyst is dangerous. Here you’ll understand the size and characteristics of liver cysts along with its symptoms.

Key Takeaways

• Most liver cysts less than 3 cm are harmless and require no treatment

• Cysts larger than 5 cm may cause symptoms that may prompt medical care

• Only 5-10% of people with liver cysts manifest symptoms

• Simple cysts don’t turn to cancer, even when they’re large

• Treatment is usually needed only if symptoms affect your daily life

• See a doctor if you have pain, bloating, or a fast-growing cyst

What are liver cysts?

Liver cysts are sacs filled with fluid that grows in the liver. The majority of these cysts are not harmful. They can be found incidentally (by chance) during scans that are originally done for other health concerns. There are few types of liver cysts, but most of them do not cause problems. These vary in size from a few millimeters to several centimeters.

These cysts are pretty common affecting about 5-10% of people worldwide. In the United States, the prevalence is higher at 15-18%. And most people with this condition never know they have them because they are without symptoms (asymptomatic).

What are the types of liver cysts?

There are three major types of liver cysts. Each of these types has different causes and potential health implications:

• Simple cysts. They develop from birth (congenital malformation of the bile duct).  They contain clear, thin fluid, and have very thin walls. Almost always, these are harmless (benign) and rarely cause complications.

• Hydatid cysts. These develop as a result of infection from a parasite called Echinococcus. It is rare in the US but more common in areas where there is large practice of sheep farming such as parts of Europe, Africa, South America, and Australia. But unlike simple cysts, hydatid cysts can cause serious health problems when they rupture and spread parasitic material in the body.

• Polycystic liver disease. This is usually a genetic problem where multiple cysts grow in the liver. It often occurs along with polycystic kidney disease. In this condition, numerous cysts develop in varying sizes, causing the liver to enlarge significantly (hepatomegaly). While people with this type of liver cyst may remain asymptomatic, some of them develop complications particularly when the cysts grow and multiply.

Among these three types of liver cysts, simple cysts are by far the most common types and may not produce symptoms at all.

What causes liver cysts?

Liver cysts develop due to few distinct causes, including:

• Congenital malformations. Most simple liver cysts are present from birth, formed during development in pregnancy when small errors occur in the formation of bile ducts. These malformations result in small, isolated areas or sacs that are filled with fluid in time. While these cysts are present from birth, they often develop slowly and may not be detectable until adulthood.

Photo Credits: Centers for Disease Control and Prevention

• Parasitic infections. Hydatid cysts form when you accidentally eat the eggs of the Echinococcus parasite. You can get this either from contact with contaminated dog feces or eating food or water contaminated with these eggs. Once the parasite is inside the human body, the egg develops into larvae, which migrate to the liver and form cysts. These cysts can grow for months or years.

• Genetic disorders. Polycystic liver disease can be inherited in an autosomal dominant fashion—you inherit the gene on a non-sex chromosome so it affects both males and females. If one of your parents has a mutation, there is a 50% chance that you inherit the trait and develop this condition. This genetic mutation affects proteins that regulate cell growth and division in the liver, leading to cyst formation.

It is important to note that while most cysts can be present from birth, they grow slowly over time, which is why some of these are often discovered until middle age or later when patients undergo imaging tests for another medical reason. This is called incidental finding.

Are All Liver Cysts Dangerous?

No, the vast majority of liver cysts are not dangerous. Simple liver cysts, for example, are the most common and they rarely pose health risks or damage liver function. It is important to emphasize that these cysts are generally harmless and often require no treatment or intervention at all.

But certain instances make liver cysts potentially problematic. And, this happens if the cyst has the following characteristics:

• Very large size (generally more than 5 cm in diameter)

• Parasitic cause (hydatid cysts)

• Development of symptoms like pain  or discomfort

• Fast-growing cysts

• Development of complications like infection or bile duct compression or obstruction

According to a study published in the Journal of Medicine and Life, about 5-10% of cases develop symptoms. And about 90-95% may have cysts but do not develop adverse effects in their lifetime. Large cysts may not even present with symptoms, which is why incidental findings of these cysts are fairly common.

How to tell if a liver cyst is benign or potentially harmful?

To know whether cysts are benign (harmless) or potentially harmful, there are several key factors that distinguish them.

Characteristics of likely harmless cysts:

• Smaller size (below 3 cm in diameter)

• Absence of symptoms

• Stable size over time (not growing or growing very slowly)

• Simple appearance on imaging (thin-walled, fluid-filled with no solid components)

• No septations (internal divisions) present or calcifications

Characteristics that might require medical investigation:

• Larger size (more than 5 cm in diameter)

• Fast-growing cysts documented by imaging

• Complex appearance in imaging studies (thick walls, septations, and presence of solid components)

• Classified as hydatid cyst based on blood tests and imaging studies

Medical professionals use different imaging techniques to assess liver cysts. Most cysts are identified incidentally in ultrasound, CT, or MRI scans that are performed for totally unrelated reasons. These imaging techniques allow doctors to examine how large the cysts are, their structure, and characteristics. It helps in identifying whether the cysts would pose a health threat or are just benign growth.

However, when cysts possess potentially concerning features, it does not automatically mean they are harmful—because many of these may still turn out to be benign. It just means that these cysts may require further testing or monitoring.

What size of liver cyst is dangerous?

The size of the liver cyst is one of the key factors that determine whether it will potentially cause problems. While size alone does not determine its actual danger, it is often correlated with the likelihood of developing symptoms or complications. Here’s a general overview of the relationship between liver cyst size and its risk:

According to a study published in Surgery in Practice and Science, surgery is done only when the diameter of the cysts goes beyond 4-5 cm, symptoms, and if the cyst is still increasing in size. The study also noted that the majority of the cases at the time of diagnosis were symptomatic, presenting with abdominal pain. But the symptoms vary depending on their location. Apart from abdominal pain, some symptoms include feeling full (satiety), dyspepsia (discomfort at the upper part of the belly), and other uncomfortable sensations.

Nonetheless, the decision whether to treat the cyst requires monitoring and watchful waiting of symptoms and complications rather than relying on the size alone. Even when the cyst is more than 4 cm but it remains unchanged for years on follow-up imaging and does not cause symptoms, intervention may not be necessary at all.

When Should You Seek Medical Attention for a Liver Cyst?

You should seek medical attention if you have the following:

• A diagnosis of liver cyst that’s larger than 5 cm

• You experience persistent pain located at the upper right quadrant of your abdomen

• You notice bloating or early satiety (feeling full quickly when eating)

• You have a known cyst that rapidly changes in diameter between follow-up imaging

• You develop jaundice (yellow discoloration of skin or eyes)

• You experience fever at any time after the diagnosis of liver cysts

It is important that any liver cyst that causes apparent symptoms warrants a medical investigation, regardless of its size. It is not only applicable to larger cysts but also small ones. If you have been diagnosed with liver cysts before and you begin experiencing new or worsening symptoms, a consult to your attending physician is recommended.

If your doctor requests follow-up imaging at a later date, it is important to keep up with it. 

Your doctor may also request ultrasound or other imaging modalities to know whether the cysts progressed or have remained stable over time.

What Are The Symptoms of a Large or Dangerous Cyst?

When liver cysts grow large enough to push through tissues, surrounding organs, biliary structures, or on the liver capsule, they may result in:

• Dull, aching pain or discomfort at the upper right abdomen

• Abdominal distension or visible enlargement of the belly

• Early satiety

• Nausea or vomiting particularly after meals

• Palpable mass right under the right rib cage

These are called pressure symptoms, which can only happen when the cyst is large enough (particularly those that exceed 5 cm in diameter). According to the Journal in Hepatology, some liver cysts may induce compression of the bile ducts, but this rarely happens. Therefore, you need to remember that some people, even those with large cysts, remain without symptoms for years or even through their lifetime.

These symptoms are dependent not only in size but also on its location or its proximity to sensitive tissues or organs. While the condition is present equally in both men and women, women tend to experience it earlier and more severely than men emphasizing the role of female hormones.

What Are The Rare But Serious Complications of Liver Cysts?

There are instances, though uncommon and rare, that liver cysts can lead to serious consequences, including:

• Infection. Bacteria may infect a cyst, which could manifest as fever, increasing pain, and elevated white blood cell count. If left untreated, it could potentially become problematic.

• Rupture. A cyst may suddenly break open spontaneously, which spills its contents to the abdominal cavity. It will cause sudden, severe pain and would require immediate medical attention.

• Bile duct obstruction. When cysts become large enough and are located near the major bile ducts, it can cause compression of these structures. When this happens, it can result in jaundice and abnormal liver function tests.

• Hemorrhage. On very rare occasions, cysts may bleed, which cause rapid expansion of the cyst and pain.

These complications are rare. However, if you experience any of these, manifested by a sudden, severe abdominal pain, fever, or jaundice in the face of a known liver cyst diagnosis, you need to seek medical attention immediately. Prompt treatment for ruptured, bleeding, or infected cyst is essential to prevent further complications.

When you have hydatid cysts, it carries with it additional risks compared to simple cysts. When they rupture, it may cause a severe allergic reaction and can spread the parasite to other regions of the body. This is the reason why hydatid cysts require treatment even when symptoms are not yet present or the size is still small.

When Should a Liver Cyst be Treated or Removed?

While the majority of cysts require watchful waiting and periodic monitoring only, there are exceptions to this rule. Understanding when treatment is needed can help you make informed decisions and be able to discuss this with your healthcare provider.

What Are the Criteria For Treating a Liver Cyst?

Doctors consider several factors when considering treatment and appropriate management to liver cysts. It may include the following criteria:

• Size. This is the most important factor that determines the course of action in the treatment and management of liver cysts. However, as mentioned repeatedly, large- and stable-sized liver cysts without producing symptoms, generally do not require treatment or removal. This means that size alone should not be used as a factor to decide whether or not to treat the condition.

• Severity of symptoms. Persistent pain, discomfort, or other symptoms that affect the patient’s quality of life.

• Growth. Fast-growing liver cysts generally require medical attention.

• Presence of complications. Infection, rupture, bleeding, or bile duct obstruction changes the course of management for liver cysts.

• Type of cyst. Hydatid cysts require treatment regardless of size and symptoms. This is because they are riskier compared to simple cysts.

It is important to recognize the criteria to put your mind at ease when you are faced with a liver cyst diagnosis. Generally, these cysts when incidentally found do not require treatment at all but may require periodic monitoring.

The decision to remove or treat a liver cysts follows the central principle of whether it outweighs the risk of the procedure. If the cyst poses no immediate threat, watchful waiting and monitoring is the best approach.

What Are The Surgical And Non-Surgical Options for Liver Cysts?

There are several options both surgically and non-surgically for liver cysts:

Non-Surgical Options

• Watchful waiting

• Percutaneous aspiration (a procedure where needle is inserted to the cyst to drain the fluid, which is sometimes combined with sclerosing agents to reduce the chance of recurrence)

• Medical therapy like albendazole for hydatid cysts. This kills the parasite and it frees you from its potential risks.

Surgical Options

• Laparoscopic fenestration/unroofing. This is a minimally invasive surgery that opens and drains the cyst, and removes part of its wall to decrease its recurrence rate.

• Cyst enucleation. This procedure removes the entire cyst while preserving the surrounding tissues.

• Liver resection. This procedure requires removal of a portion of the liver that contains the cyst. However, this is reserved for complicated cases or when several cysts are present in one portion.

Most surgical intervention is reserved for cases that are complicated and for symptomatic cases. But the general treatment for simple cases only includes non-surgical options like watchful waiting and periodic monitoring.

Recurrence rates reach up to 15% particularly in unroofing procedures but until today there still has been no consensus as to how to manage these recurrences. Laparoscopic procedures generally have lower downtime (meaning shorter hospital stays and faster recovery time). This is because there is no big incision (cut) that is involved.

How Are Liver Cysts Diagnosed?

As discussed, liver cysts are more often than not incidental findings. You may be undergoing imaging studies for a completely different condition and the cysts are found just sitting there harmless. However, it is important to understand the diagnostic process so you know what to expect if you are suspected of having a liver cyst.

What Diagnostic Tests Are Used For Liver Cysts?

Imaging modalities play important roles in the diagnosis of liver cysts. Additionally, it also helps in characterizing the cysts as well as its properties. Common modalities used include:

• Ultrasound. This is a non-invasive imaging technique that uses sound waves to create images of the liver. It is generally used first when liver conditions are suspected. It can readily identify fluid-filled structures and can provide general information like the size, number, and basic properties. It does not use radiation and is relatively expensive and therefore accessible for many patients.

• Computed Tomography (CT) scan. This imaging technique uses multiple “cuts” and provides a detailed cross-sectional image of the liver. It gives more detailed information, clearly showing the size, shape, and even density of the cysts. It helps in identifying simple cysts from liver lesions.

• Magnetic Resonance Imaging (MRI). This gives a highly detailed image of soft tissues—to which the liver belongs. It is excellent for characterizing the internal components of the cysts and detect subtle features that may give an impression of whether it is just a simple cyst or something else. It gives valuable information in evaluating complex cysts or distinguishing between cystic and solid liver lesions.

The imaging criteria for evaluating liver cysts are:

• Size and number

• Internal components

• Wall thickness and regularity

• Presence of septations or solid components

• Enhancement patterns (if a contrast is used)

• Surrounding liver tissue status

Now what roles do blood tests play in the diagnosis of liver cysts? It cannot directly tell whether a cyst exists but it is important in assessing liver function. It can also check for specific antibodies particularly in the case of hydatid cysts. Laboratory tests can also be helpful should the cysts become infected through the white blood cell count.

Conclusion

Most liver cysts are discovered incidentally. You may have it for the rest of your life without it causing any problem. When an imaging leads to its discovery, there is often a question of what size of liver cyst is dangerous. Size alone, as you know in this discussion, does not determine the outcome of the cyst or whether it poses a health threat to you.

CTA: If you need more information regarding liver health, read more in our blog today!

Frequently Asked Questions

When do liver cysts become dangerous?

Generally, larger cysts such as those exceeding 5 cm may pose some threat (though it doesn’t always. But those that produce symptoms like pain, infection, or pressure symptoms require prompt medical attention.

Can small liver cysts become dangerous?

Small liver cysts are generally benign and will not produce symptoms. But, they pose a health threat if they rupture, bleed, or become infected.

When should you seek treatment for liver cysts?

Treatment is recommended if the liver cyst is proven to be another type—hydatid cyst. It is also advised for larger cysts or those causing symptomatic problems to the patient.

 

Written by Jaclyn P. Leyson-Azuela, RMT, MD, MPH
Jaclyn P. Leyson-Azuela, RMT, MD, MPH, is a licensed General Practitioner and Public Health Expert. She currently serves as a physician in private practice, combining clinical care with her passion for preventive health and community wellness.

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