Polycystic Liver Disease

Polycystic liver disease is a rare genetic condition where numerous fluid-filled sacs develop throughout the liver, often without symptoms but sometimes causing significant discomfort as the cysts grow larger over time.

Table of contents

• What is Polycystic Liver Disease?
• Types of Polycystic Liver Disease
• Causes and Genetic Factors
• Risk Factors
• Symptoms
• Complications
• Diagnosis
• Treatment and Management
• Outlook and Life Expectancy

What is Polycystic Liver Disease?

Polycystic liver disease (PLD) is a rare genetic disorder characterized by the development of multiple fluid-filled sacs, called cysts, throughout the liver^[1]. A cyst is a closed pocket of tissue that contains liquid or other material. While a healthy liver has a smooth, uniform appearance, a liver affected by PLD can look like a cluster of grapes^[1].

The disease is defined by the presence of 10 or more cysts in the liver, though some medical sources specify 20 or more cysts for diagnosis^[8][9]. These cysts can vary significantly in size, from no bigger than a pinhead to almost 4 inches (about 10 centimeters) wide, and in some cases can grow even larger than 15 centimeters in diameter^[4][18].

Most people with polycystic liver disease do not experience any symptoms and may not even know they have the condition^[1]. Many cases are discovered accidentally during imaging tests performed for other reasons^[2]. It is estimated that around 5 to 10 in every 100 people worldwide have liver cysts, but polycystic liver disease itself is much rarer, affecting approximately 1 in every 100,000 people^[9][22].

• Liver
• Biliary tree (bile ducts)

Types of Polycystic Liver Disease

Polycystic liver disease can occur in different forms, and understanding these distinctions is important for proper diagnosis and management.

The most common form is PLD associated with autosomal dominant polycystic kidney disease (ADPKD). This accounts for about 70% to 80% of all PLD cases^[1][22]. In this form, people develop cysts in both their kidneys and liver. The severity of involvement in both organs can vary greatly from person to person. Most people with ADPKD have liver cysts by their mid-thirties^[5]. While the kidney disease can progress to kidney failure requiring dialysis or transplant, the liver typically continues to function normally despite the cysts^[2].

The second form is called isolated polycystic liver disease (also known as autosomal dominant polycystic liver disease or ADPLD). This less common form occurs by itself, affecting only the liver without kidney involvement. It accounts for about 20% to 30% of PLD cases^[1][6]. Isolated PLD tends to have a later onset in life compared to ADPKD-associated PLD, with symptoms usually appearing in adulthood^[1]. People with isolated PLD generally have better long-term outcomes overall, largely due to the absence of kidney disease^[3].

A third, much rarer form involves PLD associated with autosomal recessive polycystic kidney disease (ARPKD). This form is more likely to cause liver scarring (fibrosis) rather than typical cysts^[22].

There is also a condition called Von Meyenburg complexes (VMC), which involves small, non-hereditary cysts that are characteristic nodular lesions. These usually remain silent throughout a person’s life^[6].

Causes and Genetic Factors

Polycystic liver disease is a genetic condition, meaning it is caused by changes in a person’s genes. In most cases, the disease is inherited from a parent, though it can occasionally occur randomly without a family history^[1][4].

The disease results from the abnormal development of the biliary tree, which is the network of tubes that carry bile from the liver. During fetal development, a structure called the ductal plate forms around blood vessels in the developing liver. When this process goes wrong—called ductal plate malformation—it leads to the formation of cysts that become separated from the normal biliary system^[6].

In isolated polycystic liver disease, genetic changes in several genes have been identified. The PRKCSH and SEC63 genes are the most commonly involved, responsible for making proteins called hepatocystin and sec-63^[2][11]. These proteins play important roles in fluid transportation and the growth of cells lining the bile ducts. When these genes are mutated, normal cell processes are disrupted, leading to cyst formation.

Other genes linked to isolated PLD include ALG8, GANAB, LRP5, and PKHD^[1]. However, these genes account for less than 50% of all cases, meaning many other genes likely contribute to the condition^[1][22].

In PLD associated with ADPKD, the genes PKD1 and PKD2 are responsible. These genes make proteins called polycystin 1 and polycystin 2, which regulate fluid secretion and cell growth^[2][11]. Mutations in these genes lead to abnormal fluid secretion and uncontrolled growth, ultimately causing cyst formation in both the kidneys and liver.

Most cases of PLD follow an autosomal dominant pattern of inheritance. This means that having just one copy of the mutated gene (inherited from one parent) is enough to cause the disease. If a parent has PLD, each of their children has a 50% chance of inheriting the condition^[22]. However, even within the same family, the severity of the disease can vary greatly—some people may have many large cysts while others have few symptoms^[3].

Risk Factors

Several factors can increase the likelihood of developing polycystic liver disease or experiencing more severe symptoms.

The most significant risk factor is having a family history of the condition. Because PLD is usually inherited, people with a parent or sibling who has the disease are at increased risk^[4]. If you or someone in your immediate family has PLD, other family members should be tested for it^[4].

Females are much more likely than males to develop polycystic liver disease and to have more severe symptoms. Women are affected by more severe disease compared to men and are six times more likely to have symptoms^[4][22]. This is because the hormone estrogen stimulates cyst growth^[1]. The cysts tend to grow larger and more numerous in women, particularly during pregnancy or with the use of estrogen-containing medications like birth control pills or hormone replacement therapy.

Age is another factor. Most people don’t discover they have PLD until they are adults, typically around age 50, when the cysts become large enough to cause symptoms or be detected on imaging^[4][18].

Having polycystic kidney disease, particularly ADPKD, is a strong risk factor for developing liver cysts. The frequency of liver cysts in ADPKD increases with age and with advanced kidney disease^[4].

Symptoms

Most people with polycystic liver disease do not experience any symptoms, especially in the early stages^[1][2]. Many individuals may not even know they have the condition. The cysts can be present for years without causing problems, and the liver usually continues to function normally despite their presence^[3][4].

However, if the liver becomes very enlarged and bulky with cysts, symptoms may develop. Only about one out of every 10 people with PLD experiences problems associated with it^[4]. When symptoms do occur, they typically appear around age 50^[18].

The most common symptoms include:

• Abdominal pain and swelling: These are the most frequent symptoms of PLD. The pain can be sharp or dull and may occur in the upper right part of the abdomen where the liver is located. A swollen abdomen can result from the enlarged liver itself or from fluid buildup called ascites^[1][4].
• Feeling full quickly (early satiety): A large liver full of cysts can crowd the stomach, making you feel full after eating only a small amount of food^[1][4].
• Shortness of breath: If cysts become very large, they can press upward on the diaphragm, which is the muscle that separates the chest from the abdomen and plays an important role in breathing. This pressure can make it difficult to take a deep breath^[1][4].

Less common symptoms include:

• Back pain: This can occur if the enlarged liver pushes on back muscles^[1].
• Heartburn: A large liver can put pressure on the stomach, causing stomach acid to flow back up into the esophagus (the tube connecting the mouth to the stomach)^[1].
• Difficulty bending: The enlarged liver can make it physically difficult to bend forward^[9].
• Bloating: A feeling of fullness or tightness in the abdomen^[4].

These symptoms result from the liver taking up too much space in the abdomen, which can affect quality of life and the ability to perform daily activities^[3][9].

Complications

While polycystic liver disease is generally not life-threatening and the liver continues to function normally in most cases, some people may experience complications^[4].

The most serious complications, though rare, include:

• Bleeding into a cyst: A cyst can rupture or bleed internally, causing sudden severe abdominal pain^[4]. This can lead to internal bleeding and requires immediate medical attention^[9].
• Infection of a cyst: Cysts can become infected, causing fever and acute pain^[1][4]. If you experience sudden severe pain along with fever, you should seek emergency medical care immediately^[9].
• Bile duct obstruction: Large cysts can press on bile ducts, blocking the flow of bile. This can lead to jaundice, which is a yellowing of the skin and the whites of the eyes^[4].
• Portal hypertension: In rare cases, cysts can cause high blood pressure in the major vein that leads to the liver^[18].
• Liver fibrosis: Excessive scar tissue can develop within the liver, though this is uncommon^[18].

If PLD is associated with ADPKD, additional complications related to the kidneys are common. These can include kidney failure, high blood pressure, and the need for dialysis or kidney transplant^[2]. ADPKD can also cause cysts in other organs and increase the risk of brain aneurysms (abnormal bulges in blood vessels in the brain)^[23].

Despite the presence of cysts, liver function typically remains preserved for a long time in PLD^[6]. The liver is able to continue its essential functions even with numerous cysts present.

Diagnosis

Because most people with polycystic liver disease do not have symptoms, many cases are discovered accidentally during imaging tests ordered for other reasons^[2][3]. This is called an incidental finding.

When PLD is suspected, doctors use several methods to confirm the diagnosis:

Imaging tests are the primary tools for diagnosing PLD. An ultrasound is typically the first test used to look for the presence of liver cysts^[4]. Ultrasound uses sound waves to create images of internal organs. Other imaging tests include computed tomography (CT) scans and magnetic resonance imaging (MRI)^[2][3]. These tests provide detailed pictures that allow doctors to see the number, size, and location of cysts throughout the liver.

The diagnosis of PLD is based on specific criteria that take into account family history, age, and the number of cysts. You may be diagnosed with polycystic liver disease if:

• You have a family member with PLD, are under the age of 40, and have more than one cyst
• You have a family member with PLD, are older than 40, and have more than three cysts
• You have no family members with PLD, are over the age of 40, and have more than 20 cysts^[4]

Before confirming a diagnosis of isolated PLD, doctors must rule out ADPKD. To do this, they will request scans of the kidneys to check for kidney cysts^[3][18]. If no kidney cysts are present, or if there are too few to qualify for a diagnosis of ADPKD, the condition is assumed to be isolated PLD.

Blood tests may be performed to check liver function. In most cases, liver function tests remain normal even with numerous cysts present^[9].

Physical examination may reveal an enlarged liver that the doctor can feel during an abdominal exam^[9].

Genetic testing can be helpful in ambiguous cases or for family screening. Testing for mutations in the genes known to cause PLD (such as PRKCSH and SEC63 for isolated PLD, or PKD1 and PKD2 for ADPKD) can confirm the clinical diagnosis^[6].

Taking a medical history is important to determine whether other family members have had this condition, as PLD often runs in families^[9].

Treatment and Management

Treatment for polycystic liver disease is usually not needed unless symptoms develop^[4]. For most people with PLD, a conservative approach with regular monitoring is recommended^[2].

Conservative management is appropriate for people with mild or no symptoms. This includes regular check-ups with imaging to monitor cyst growth and liver size. If you have been diagnosed with ADPKD, you should be offered a liver scan to check for liver cysts^[5].

Medication options include:

• Pain medication: Mild pain associated with PLD can be treated with pain relievers^[7].
• Somatostatin analogs: Injectable medications such as octreotide and lanreotide can be used to reduce liver volume in people with widespread cysts and severe symptoms^[3][8]. These medications are given as small injections every 4 weeks and have been shown to reduce the volume of cysts, easing the feeling of fullness and allowing patients to eat more normally^[3][14]. However, these medications have not yet been approved by regulatory agencies specifically for PLD treatment and are being used on an experimental basis^[3].
• Antibiotics: If a cyst becomes infected, antibiotics are prescribed to treat the infection^[9].
• Stopping estrogen-containing medications: Women may be advised to discontinue birth control pills or hormone replacement therapy, as estrogen can stimulate cyst growth^[9].

Surgical procedures may be considered for people with significant symptoms or complications:

• Aspiration with sclerotherapy: This procedure involves draining fluid from large cysts using a needle and then injecting a substance to prevent the cyst from refilling^[8][23].
• Cyst fenestration (also called deroofing): This surgical procedure involves removing the walls of cysts to decompress the liver. It can shrink a large, dominant cyst by more than 90%^[3][8].
• Hepatic resection (liver resection): In cases where cysts are concentrated in one part of the liver, surgeons can remove that section of the liver^[2][7][9].
• Liver transplantation: In extreme cases where the liver becomes massively enlarged and causes severe symptoms that cannot be managed by other means, liver transplantation may be required^[2][7][8]. This is the only curative treatment for PLD^[8][9]. However, it is reserved for patients with severely impaired quality of life due to massive liver enlargement.

The main goal of treatment for symptomatic PLD is to decrease liver volume to allow abdominal decompression and improve symptoms^[2][23]. Treatment decisions are based on the liver’s appearance on imaging, the severity of symptoms, and the patient’s quality of life^[6].

Lifestyle modifications may also help:

• Eating smaller, more frequent meals if you feel full quickly
• Avoiding activities that might traumatize the abdomen
• Staying hydrated
• Avoiding medications that can harm the liver unless prescribed by your doctor

Some people with PLD may benefit from enrolling in clinical trials to access experimental treatments^[3].

Outlook and Life Expectancy

The outlook for people with polycystic liver disease is generally good, particularly for those with isolated PLD. Most people with the condition live a normal life and do not experience symptoms^[4].

Polycystic liver disease is a progressive condition, meaning the cysts tend to grow larger and increase in number over time^[2]. However, only a small subset of patients develop severe symptoms that require treatment. The disease progresses at different rates in different people, and the severity can vary greatly even within the same family^[3].

Despite the presence of numerous cysts, liver function typically remains preserved for a long time^[6]. The liver continues to perform its essential functions even with extensive cyst involvement. In most cases, the disease is not considered life-threatening^[4].

Long-term outcomes are better overall in isolated PLD compared to PLD associated with ADPKD, largely due to the absence of chronic kidney disease in the isolated form^[3]. People with ADPKD face additional challenges related to kidney function, including the potential need for dialysis or kidney transplantation^[2].

For those who do develop symptoms, early diagnosis and appropriate treatment can help manage the condition and prevent complications^[1]. With advances in medical therapies and surgical techniques, doctors are increasingly able to provide relief for patients with symptomatic PLD^[8].

If you have PLD or a family history of the condition, regular monitoring by your healthcare provider is important. This allows for early detection of any changes and timely intervention if symptoms develop.