A hepatic cyst is a fluid-filled sac that forms in the liver. Most are simple cysts, completely benign, and never cause symptoms. They’re believed to be present from birth, forming when tiny bile duct structures fail to connect properly to the rest of the biliary system during development. The result is a small pocket that fills with fluid over time. Cysts smaller than about 4 centimeters (roughly 1.5 inches) across rarely cause any trouble, and many people discover them only by accident during an imaging scan for something else.
How Simple Liver Cysts Form
Simple hepatic cysts are lined with the same type of cells that line bile ducts, which is why researchers think they originate from bile duct tissue. During fetal development, microscopic clusters of bile duct cells sometimes form but never link up with the main network of ducts that carry bile out of the liver. These isolated clusters, called biliary microhamartomas, gradually expand and fill with fluid. Despite their bile duct origin, the cysts rarely contain actual bile.
This process is not caused by anything you did or were exposed to. It’s a developmental quirk, and it’s common. Simple cysts can be single or multiple, and they can range from a few millimeters to well over 10 centimeters.
When Cysts Cause Symptoms
Most liver cysts produce no symptoms at all. When they do, it’s usually because they’ve grown large enough to press on surrounding structures. Cysts over 4 centimeters are more likely to cause problems, though even large cysts can remain silent. The most common complaint is a dull ache or sense of fullness in the upper right abdomen. Very large cysts can press on the stomach, causing early fullness after eating or nausea.
Rarely, a cyst can bleed internally or rupture. A literature review found only 18 reported cases of ruptured simple liver cysts since 1970, so this is genuinely uncommon. When it does happen, the hallmark is sudden, severe pain in the right upper abdomen. Nearly all of those reported ruptures involved hemorrhage, and most required surgical intervention.
Types of Liver Cysts Beyond Simple Cysts
Not every cyst in the liver is a simple cyst. Several other types exist, and they differ in cause, appearance, and how they’re managed.
Polycystic Liver Disease
Some people develop dozens or even hundreds of cysts throughout their liver. This condition, called polycystic liver disease, is genetic. It can occur on its own (autosomal dominant polycystic liver disease) or alongside polycystic kidney disease. Several gene mutations are involved, most notably in genes called PRKCSH and SEC63. The liver continues to function well in most cases, but the sheer volume of cysts can enlarge the organ significantly and cause discomfort or complications from mass effect.
Biliary Cystic Neoplasms
These are rare growths that can look similar to simple cysts on imaging but carry a risk of becoming cancerous. They predominantly affect women between ages 30 and 50. On a CT scan, they often appear as well-contained masses with internal dividers (septations), small solid nodules along the wall, or walls that light up with contrast dye. Simple cysts, by contrast, typically appear as smooth, round, thin-walled sacs filled with uniform fluid. The distinction matters because biliary cystic neoplasms usually require surgical removal, while simple cysts generally don’t. In some cases the imaging features of the two overlap, making a definitive diagnosis on imaging alone difficult.
Parasitic (Hydatid) Cysts
In parts of the world where livestock farming is common, a tapeworm called Echinococcus can cause cysts in the liver. These hydatid cysts have a distinctive layered structure and sometimes contain smaller “daughter cysts” inside. They’re treated with antiparasitic medications, and larger cysts (over 7.5 centimeters) often require surgery. A key concern during any procedure on a hydatid cyst is spillage of its contents, which can trigger a severe allergic reaction or spread the infection.
How Liver Cysts Are Found
The vast majority of simple hepatic cysts are discovered incidentally on an ultrasound, CT scan, or MRI performed for an unrelated reason. On ultrasound, a simple cyst appears as a dark, round structure with sharp borders and no internal debris. On CT, it shows up as a smooth, very low-density area with a wall so thin it’s essentially invisible. These classic features are usually enough for a confident diagnosis without any further workup.
If a cyst has unusual features, such as thick walls, internal septations, solid components, or irregular edges, your doctor may order additional imaging or follow-up scans to rule out a neoplasm or other cause.
Treatment Options
Simple liver cysts that cause no symptoms don’t need treatment. They’re typically left alone, and many never need to be checked again once they’ve been confirmed as simple on imaging.
Aspiration and Sclerotherapy
For cysts that are causing pain or discomfort, one option is to drain the fluid with a needle (aspiration) and then inject a chemical agent to collapse the cyst walls and prevent refilling. This is called sclerotherapy. Agents commonly used include ethanol, polidocanol, and tetracycline-based solutions. A systematic review found that this approach reduces cyst volume by 76% to 100%, with symptom relief achieved in 72% to 100% of patients over follow-up periods ranging from 2 to 54 months. Both ethanol and non-ethanol agents showed comparable effectiveness, with volume reductions of 84 to 99% and 88 to 100%, respectively.
The advantage of sclerotherapy is that it’s minimally invasive, performed through the skin with imaging guidance. The downside is that some cysts do refill over time, potentially requiring repeat treatment.
Surgical Deroofing
When sclerotherapy isn’t suitable or a cyst keeps recurring, surgery is the next step. The most common procedure is laparoscopic deroofing: the surgeon removes the portion of the cyst wall that’s exposed on the liver surface, allowing the fluid to drain freely into the abdominal cavity where the body reabsorbs it. This can be done through small incisions with a camera.
Deroofing works well for most patients, but recurrence is possible. In one study of 33 surgically treated patients, five who had laparoscopic deroofing experienced symptomatic recurrence. Some of those required a more extensive liver resection to solve the problem. Open surgery (through a larger incision) does not appear to offer a lower recurrence rate compared to laparoscopic deroofing, so the less invasive approach is generally preferred.
Liver Resection
In rare situations, particularly when cysts recur after deroofing or when polycystic liver disease causes severe symptoms, removing a section of the liver may be necessary. The liver regenerates well, so even the removal of a significant portion is usually tolerated, though this is reserved for cases where less invasive options have failed.
Living With a Liver Cyst
If you’ve been told you have a simple liver cyst, the most important thing to know is that it poses no cancer risk and almost certainly won’t affect your liver function. There are no dietary changes or lifestyle modifications needed. You don’t need to avoid exercise or physical activity. In most cases, a single imaging study confirming it’s a simple cyst is all the follow-up you’ll ever need.
If a cyst is large or you develop new symptoms like persistent upper abdominal pain, nausea, or a palpable mass, those are worth bringing up with your doctor, since large or growing cysts occasionally warrant treatment or closer evaluation to confirm they’re still benign.