Splenic Cyst Found on a Scan: Should You Be Worried?

A splenic cyst found on a scan is usually an incidental, benign finding: a fluid-filled pocket in the spleen that was seen while looking for something else. Most cause no symptoms. A cyst that looks simple on ultrasound, CT or MRI usually does not need further scans, while large or symptomatic cysts may need more review.

This guide is for adults who have a scan report mentioning a cyst in the spleen. It explains common report wording and what to ask. It cannot tell you what your cyst is or whether it needs treatment; that is for the team who can see your images.

A ruptured spleen is a medical emergency because it can cause serious internal bleeding. Rupture of a splenic cyst is rare, and most ruptures of the spleen follow an injury. Go to an emergency department or call emergency services if you have:

• Sudden or severe pain under the left ribs or in the upper left abdomen.
• Pain spreading to the left shoulder or left side of the chest, which may be worse when breathing in.
• Dizziness, fainting, confusion, a fast heartbeat, paleness or blurred vision.
• Any of these after a fall, a blow to the abdomen or a car accident, even days or weeks later.

The spleen sits under the ribs on the left side, above the stomach. It helps fight infection and filters old or damaged blood cells. A cyst is a rounded area filled with fluid inside it.

Splenic cysts are uncommon overall. A review of imaging studies quotes an incidence of about 0.07% in a large autopsy series, and notes that cysts are usually solitary, incidental and without symptoms. On ultrasound, a simple cyst looks like a well-defined round area with a thin wall and clear fluid. On CT, it appears dark and does not take up contrast dye.

Because most splenic cysts cause no symptoms, they are often first noticed on an ultrasound, CT or MRI done for an unrelated reason, such as abdominal pain, a kidney check or a scan after an accident. Finding one this way is common for incidental findings and does not by itself suggest anything serious.

Report wording may name the type, or the radiologist may simply describe a cyst. The main groups are:

CDC describes hydatid disease as causing slowly enlarging cysts, mainly in the liver and lungs, that often grow unnoticed for years without symptoms. If a parasitic cause is being considered, clinicians may ask about where you have lived or travelled, contact with dogs or livestock, and whether other organs have cysts. Tell your clinician about this history, as it can change how the cyst is assessed.

• Primary or true cysts, sometimes called epithelial or epidermoid cysts. These have a cell lining, are thought to be present from birth and are less common.
• Secondary cysts, also called pseudocysts or false cysts. These have a fibrous wall and most often follow an earlier injury to the spleen, sometimes one the person does not remember.
• Parasitic (hydatid) cysts, caused by a tapeworm infection linked with dogs and livestock such as sheep. They are rare in the spleen and more likely in people who have lived in areas where the infection is common.

Often, no. A radiology review states that simple splenic cysts, whether primary or secondary, do not need further imaging follow-up. The radiologist decides whether a cyst looks simple based on its wall, contents and whether it enhances with contrast.

Follow-up or further imaging is more likely if the report describes thick walls, internal parts (septations), solid areas, calcification or enhancement, or if you have a history of cancer, recent travel to areas where hydatid infection is common or ongoing symptoms. Ask whether your report calls the cyst simple or uses words such as complex or indeterminate, and what the recommended next step is.

Size is one of the things surgeons consider. The same review says that splenic cysts larger than 5 cm, or those causing symptoms, are usually treated surgically, because of a higher risk of complications such as rupture, infection or bleeding. Where possible, surgeons try to keep as much of the spleen as they can.

A large cyst may press on nearby organs and cause a feeling of fullness or discomfort under the left ribs. A cyst being over a size threshold does not automatically mean an operation; the decision depends on symptoms, cyst type and your overall health. Ask for the measured size, in three dimensions if available, so it can be compared on any later scan.

Yes. Cleveland Clinic lists benign growths such as cysts among the focal causes of an enlarged spleen. If your report also mentions splenomegaly, ask whether the cyst explains the size or whether other causes, such as infection, liver disease or blood conditions, are being considered. The related guide on enlarged spleen covers those causes.

While the spleen is enlarged, the NHS advises avoiding contact sports. Ask your clinician whether this applies to you, especially if the cyst is large.

Bring the full scan report, including the measured size and the radiologist's description. These questions can help:

• Does my report describe a simple cyst, or are there features that need more checks?
• How big is the cyst, and has it changed compared with any earlier scans?
• Is any further scan recommended, and if so, which type and when?
• Could this be a pseudocyst from an earlier injury, or a parasitic cyst given my travel history?
• Should I avoid contact sports or heavy impacts?
• Which symptoms should make me seek urgent care?
• Who is responsible for my follow-up, and how will I get the results?

On SameCase, patients and verified doctors share de-identified cases. Reading cases where a splenic cyst was found by chance, along with the size, report wording and follow-up described, can show you which details clinicians focused on. We hope this helps you prepare clearer questions.

Other people's cases cannot tell you what your cyst is or whether it needs treatment. Your own clinician and the radiologist who reviewed your images should guide decisions about follow-up.