A pancreatic cyst is a closed sac of fluid that develops on or within the pancreas, an elongated gland positioned behind the stomach. The pancreas produces digestive enzymes and hormones like insulin to regulate blood sugar levels. These cysts are increasingly detected, and while many are harmless, some types carry a potential for malignant transformation. Determining the specific type of cyst is important because a small percentage of these growths can be precancerous.
Understanding the Different Types of Cysts
Pancreatic cysts are broadly categorized into two groups: non-neoplastic, which are almost universally benign, and neoplastic, which have the potential to become cancerous. The most common non-neoplastic type is the pseudocyst, which is not a true cyst but a fluid collection typically surrounded by scar or inflammatory tissue. Pseudocysts frequently form as a complication following an episode of acute or chronic pancreatitis, an inflammation of the pancreas.
Serous Cystic Neoplasms (SCNs) are nearly always benign and filled with thin, watery fluid. SCNs are often microcystic, containing many small fluid pockets, and are generally monitored unless they grow large enough to cause symptoms. The cysts that raise the most concern are the mucinous types, named for the thick, mucus-like fluid they produce.
The two main concerning types are Mucinous Cystic Neoplasms (MCNs) and Intraductal Papillary Mucinous Neoplasms (IPMNs). MCNs are large cysts that develop most often in the body or tail of the pancreas and occur almost exclusively in middle-aged women. These growths are considered precancerous and often require surgical removal to prevent progression.
Intraductal Papillary Mucinous Neoplasms (IPMNs) are the most common type of neoplastic cyst and arise from the ducts that carry pancreatic fluid. They are classified based on their location; those forming in the main pancreatic duct carry a much higher risk of malignancy than those confined to the side branches.
How Pancreatic Cysts Are Discovered
The vast majority of pancreatic cysts do not cause any noticeable symptoms and are instead discovered incidentally. This occurs when a person undergoes an abdominal imaging scan, such as a Computed Tomography (CT) or Magnetic Resonance Imaging (MRI), for an unrelated health concern. Studies suggest that these asymptomatic cysts are found in approximately 10% of people undergoing such scans.
In rare instances, a cyst may grow large enough to cause symptoms by pressing on surrounding organs or structures. When symptoms do occur, a person may experience ongoing abdominal pain that can sometimes radiate to the back. A large cyst may also cause nausea, vomiting, or a feeling of being full soon after starting to eat.
A cyst that blocks the pancreatic duct or bile duct can also cause jaundice (yellowing of the skin and eyes). The discovery of symptoms often prompts a clinical investigation that ultimately reveals the presence of the pancreatic cyst.
Assessing Risk and Treatment Options
Once a pancreatic cyst is identified, a detailed evaluation is necessary to determine its type and potential for malignancy. This process relies heavily on advanced imaging techniques, particularly magnetic resonance cholangiopancreatography (MRCP), a specialized MRI that provides detailed pictures of the pancreas and its ducts. Endoscopic Ultrasound (EUS) is often used to obtain a closer look at the cyst’s architecture, including its wall thickness and the presence of internal solid components or nodules.
Solid nodules within the cyst are considered a high-risk feature, strongly suggesting a precancerous or cancerous transformation. During an EUS procedure, fine needle aspiration may be performed to withdraw cyst fluid for laboratory analysis. This fluid is tested for markers like amylase, tumor markers, and mucin, which helps differentiate between high-risk mucinous cysts and lower-risk types.
The management strategy is primarily guided by the cyst’s risk stratification. For cysts deemed low-risk or definitively benign, such as SCNs or uncomplicated pseudocysts, the standard approach is active surveillance or watchful waiting. This involves following the cyst with periodic imaging scans to monitor for any changes in size or appearance that might indicate progression.
For cysts with high-risk features, such as main-duct IPMNs or MCNs, surgical intervention is generally recommended. The goal of surgery is to prevent the development of pancreatic cancer by removing the precancerous lesion entirely. The exact surgical procedure, which may be a distal pancreatectomy or a Whipple procedure, depends on the cyst’s location within the pancreas.