Blood tests can help us tell if the cyst is benign (noncancerous) or precancerous (can turn into cancer). Other tests to learn more about a cyst can include:

CA19-9 blood tests for pancreatic cysts: This test measures the level of a protein in the blood or cyst fluid. It can be higher if a cyst is precancerous.

Usually, people have between 0 and 37 units/milliliter (U/mL) of CA 19-9 in their blood. A range higher than that can be a marker for a pancreatic cyst. However, a higher level may not mean you have a cyst. The CA19-9 level can rise because of other conditions, such as pancreatitis.

Carcinoembryonic antigen (CEA): CEA is a protein. This test measures CEA in the blood or in fluid taken from a pancreatic cyst. The test results can help us tell if a cyst is precancerous.The level of CEA in the blood often rises in people with cancers of the gastrointestinal tract.

Liver (hepatic) function: This test measures blood for the level of bilirubin, a substance made by the liver. A high level can mean there’s a cyst or tumor blocking the bile duct. 

Doctors use imaging tests to help find and diagnose disease, recommend treatments, and monitor how well you respond to therapy. You may have more than 1 imaging test, because each kind gives us different information.

Imaging tests for a pancreatic cyst include:

Computed tomography (CT) angiography/triphasic CT scan: This This test can help tell us the location and size of a pancreatic cyst. We inject a special dye before the scan. It helps make a clearer image of the pancreas and nearby blood vessels. This method uses less radiation.

Magnetic resonance imaging (MRI) scans make very detailed 3D images of areas inside your body. This test can help us learn more about a cyst’s size and structure. MRI is different from a CT scan. It uses radio waves, a powerful magnet, and a computer to take pictures.

Magnetic resonance cholangiopancreatography (MRCP) uses radio waves, a powerful magnet, and a computer to take pictures of the pancreatic ducts. Pancreatic ducts are small channels that carry digestive enzymes to the intestines. Cysts can start in the pancreas ducts.

Endoscopic ultrasound (EUS) uses ultrasound waves to make very detailed pictures of the pancreas. This procedure uses a flexible tube with a light at the end, called an endoscope. You will have anesthesia, which is medication to make you sleep. 

Your physical exam, blood or lab tests, and imaging studies may suggest you have a pancreatic cyst. If so, we may do a biopsy to confirm the diagnosis. 

A biopsy is a procedure to take a tissue sample from the pancreas. Most biopsies are done during an  endoscopic ultrasound  (EUS). You will have anesthesia (medication to make you sleep) before this procedure.

For the biopsy, we put a thin needle into an endoscope, a flexible tube. We use ultrasound images to guide the needle into the cyst to get a sample of fluid and cells.

MSK uses very precise imaging methods to guide biopsy procedures. This lets us examine cysts in areas that are hard to reach.

We can do the carcinoembryonic antigen (CEA) blood test at the same time as the biopsy. The test results can help us tell if a cyst is precancerous.