The pancreas is a small, elongated gland located in the abdomen between the stomach and the intestines. It is composed mainly of exocrine cells, which make digestive enzymes. A very small portion of the pancreas is made of endocrine (islet) cells. These cells make hormones such as insulin, which controls blood sugar levels. The main part of the pancreas is called the body; the narrow left portion is the tail; and the broad right portion is the head.
Advances in imaging technologies such as CT and MRI have dramatically increased the number of small cysts that are detected in the pancreas. These cysts — small, fluid-filled growths — are often identified during diagnostic imaging for another condition. One study suggested that more than 2 percent of MRI scans, which are performed as part of a preventive health exam, will identify a pancreatic cyst. (1) Most of them are benign (noncancerous) and are unlikely to be harmful or cause symptoms. (2) Some are precancerous, however, and have the potential to develop into pancreatic cancer.
Nearly 20 types of cysts, including benign and precancerous growths, can arise in the pancreas. For most people, the appearance of a pancreatic cyst is a one-time event, but some types can reoccur after they are removed. The most common types of pancreatic cysts include:
The vast majority of pancreatic cysts are benign pseudocysts, which are primarily made of fluid and can develop within or next to the pancreas. Pseudocysts are a common complication of acute pancreatitis, an inflammation of the pancreas, and are unlikely to arise in people who have never had pancreatitis or another injury to the pancreas.
SCAs have thick, fibrous walls and contain a thin, clear fluid. While nearly all SCAs are benign, these cysts may cause symptoms such as pain and jaundice as they grow within the pancreas.
IPMNs, which develop within the pancreatic ducts that connect the pancreas to the intestine, are the most common type of precancerous cysts. IPMNs produce large amounts of mucin (proteins that form mucus) in their lining and fluid. Currently, doctors cannot determine if and when an IPMN will progress to cancer. However, research suggests that IPMNs that arise in older people or involve the main pancreatic duct have a higher risk of progressing to pancreatic cancer. In addition, people who have surgery to remove an IPMN may develop another IPMN in the remaining portion of the pancreas.
MCNs are mucin-producing precancerous growths that can arise in the body and tail of the pancreas. This type of cyst is less common than an IPMN and almost always occurs in women. Large MCNs that contain septations, tiny walls that divide the cyst into compartments, may be more likely to become cancerous.