Polycystic liver disease

Polycystic liver disease is the presence of multiple cysts (generally more than ten) within the liver. It is a condition of genetic origin and, in the great majority of cases, it causes no symptoms and does not affect how the liver works. If you were found to have many cysts on an ultrasound or a CT scan, you most likely need monitoring rather than treatment.

It is worth distinguishing it from a simple liver cyst, which is a single, isolated cyst, very common and unrelated to this disease. Here we are talking about a condition in which numerous cysts appear, often together with cysts in the kidney.

Is it the same as polycystic kidney disease?

Not always, and this is the most important distinction. There are two different situations:

• Polycystic liver disease associated with polycystic kidney disease: this is the most common form. The liver cysts appear in the setting of autosomal dominant polycystic kidney disease (ADPKD). Here the liver is an accompanying finding, and what usually drives the prognosis is the kidney, because of the risk of kidney failure.
• Isolated polycystic liver disease: the cysts are limited to the liver, with no significant kidney involvement. It is less common and is known as autosomal dominant polycystic liver disease (ADPLD).

In both cases the cysts arise from the lining of the bile ducts and tend to grow slowly over the years.

Why does it happen?

It is a genetic disease inherited in an autosomal dominant way, which means it is enough to inherit the altered gene from one parent to develop it, and each child of an affected person has a 50% chance of inheriting it.

• In polycystic kidney disease (ADPKD), the most common mutations are in the PKD1 and PKD2 genes, which produce the proteins polycystin 1 and 2. The form linked to PKD2 is usually milder and appears at an older age.
• In isolated polycystic liver disease, the mutations are in other genes, such as PRKCSH, SEC63, GANAB and ALG8.

Cyst growth also has a hormonal component. That is why large liver cysts are more common in women, especially in those who have had several pregnancies or used estrogens.

Does it cause symptoms?

In most people, no. The cysts are usually an incidental finding on an ultrasound or CT scan ordered for another reason. The number of cysts increases with age: in polycystic kidney disease, fewer than 10% of people under 30 have liver cysts, compared with about 40% of those over 60.

Symptoms, when they occur, are due to the enlargement of the liver (hepatomegaly) and to pressure on neighboring organs:

• Pain or heaviness in the upper right part of the abdomen.
• A feeling of getting full quickly, bloating and nausea.
• Increased abdominal girth and difficulty breathing or moving in very advanced cases.

Less frequent complications are bleeding into a cyst, which causes sudden pain, and infection of a cyst, with fever and localized pain.

Liver function is preserved

This is a reassuring point. Unlike cirrhosis, polycystic liver disease generally does not damage the liver tissue or impair its function. Blood tests are usually normal or nearly normal, and the liver keeps doing its work even when it reaches a considerable size. The problem, when there is one, is mechanical (the volume), not a loss of function.

Manifestations outside the liver

When the liver cysts are part of polycystic kidney disease, the rest of the picture must be kept in mind:

• Kidney cysts, with a risk of chronic kidney failure.
• Cysts in the pancreas and spleen.
• Brain aneurysms, present in 4 to 10% of patients. Larger ones may require treatment.
• Colon diverticula.
• Abdominal wall hernias.

How is it evaluated?

The diagnosis is based on imaging (ultrasound, CT or MRI), which shows the multiple thin-walled cysts, together with a family history of polycystic disease of the liver or kidney. When many liver cysts are found, it is worth studying the kidneys as well, to define whether this is polycystic kidney disease.

Genetic testing is not essential for the diagnosis, but it can be useful to confirm the type, guide the prognosis and support genetic counseling for the family.

Treatment

Most patients need no treatment for the liver cysts, only periodic monitoring. Treatment is reserved for those who have symptoms from the greatly enlarged liver or from complications. The options are chosen according to the number, size and location of the cysts:

• Aspiration with sclerotherapy: a large, isolated cyst is drained with an image-guided needle and a substance is injected so it does not refill.
• Fenestration: several superficial cysts are opened and unroofed through laparoscopy.
• Liver resection: the most affected part of the liver is removed, preserving the rest.
• Somatostatin analogues (such as octreotide or lanreotide): injectable drugs that modestly reduce the volume of the liver and can help control symptoms.
• Liver transplant: reserved for the most severe cases, with very large livers that do not respond to other measures. When there is also kidney failure, a combined liver and kidney transplant may be considered.

Surgery on the polycystic liver is complex and should be performed at centers experienced in hepatobiliary surgery.

Genetic counseling

Because this is an autosomal dominant inherited disease, each child of an affected person has a 50% chance of inheriting the gene. Genetic counseling makes it possible to explain this risk to the family, guide the testing of relatives who wish it, and support reproductive decisions. If you have been diagnosed with this disease, it is worth discussing with your physician.

See also

• Simple liver cyst
• Liver hemangioma
• Cirrhosis
• Liver transplant