What Are Pancreatic Cysts?

The pancreas is a 6- to 8-inch-long gland that produces enzymes that help digest food and neutralize stomach acid and hormones that help manage blood sugar. The term “pancreatic cyst” encompasses nearly 20 types of fluid-filled, balloon-like sacs that can develop alone or in clusters.

The incidence of pancreatic cysts increases with age and can occur in up to 25 percent of those older than 70, according to the American Gastroenterological Association (AGA). Asymptomatic cysts are found in about 15 percent of people who undergo abdominal MRIs. The AGA estimates that only 17 in 100,000 of those incidentally discovered cysts are found to be malignant (cancerous).

The following types of cysts are the most common:

• Pseudocysts are benign (noncancerous) and aren’t really cysts at all. They’re made of pockets of fluid lined with scar or inflammatory tissue, unlike the cells found in true cysts. They’re the most common type of pancreatic cyst, often occurring after a bout of pancreatitis (inflammation of the pancreas).

Small, asymptomatic pseudocysts often disappear on their own. Larger, persistent pseudocysts that cause pain or are infected may need to be drained. Risk factors, besides pancreatitis, include abdominal injury, gallstones, and heavy alcohol use.

• Serous cystadenomas are filled with watery fluid and are usually benign. They’re twice as likely to occur in women—especially those over 60. Most serous cysts don’t need to be treated unless they grow large or cause symptoms.

• Mucinous cystic neoplasms are slow-growing tumors that occur almost exclusively in women, usually between ages 40 and 50. Although they’re not malignant, some may progress to cancer if not treated. Whether these tumors need to be removed or closely monitored depends on several factors that diagnostic testing can help identify.

• Intraductal papillary mucinous neoplasms (IPMNs) are growths in the pancreatic ducts. They’re most common in men in their mid-60s, according to the AGA. Some IPMN subtypes are almost always precancerous. IPMNs that affect the main pancreatic duct, the tube that runs the length of the pancreas and empties digestive juices into the small bowel, are at a high risk of developing into cancer—50 to 70 percent of the time—especially in older adults. Surgery is usually recommended for main-duct cysts.

Branch-duct IPMNs, which occur when one of the smaller side branches of the main duct enlarges into a cyst, have a 15 to 20 percent lower risk of becoming malignant. Most branch-duct IPMNs don’t require surgery; surveillance with serial imaging studies is usually recommended.

Read more about treating asymptomatic pancreatic cysts and how to identify symptomatic cysts.