Pancreatic Pseudocysts

Fig. 15.1

Large pancreatic pseudocyst. © Dale Dangleben, MD

Endoscopic ultrasound (EUS) has emerged as an important adjunct, as it is useful in aspirating a sample of fluid from the pseudocyst which may be diagnostic. If fluid is sampled from the cyst, pseudocysts tend to have high amylase, low viscosity, low CEA, and low CA-125. Mucinous cystadenomas have variable amylase, high viscosity, and variable tumor markers. Serous cystadenomas have low viscosity, low CEA, but increased CA-125. Cystadenocarcinomas have high CEA, high CA-125, and positive cytology. Low CA 19-9 is strongly predictive of a non-mucinous cyst. However, percutaneous aspiration is not usually necessary for differentiation between pseudocyst and cystic neoplasms and may in fact be detrimental given the risk of seeding a sterile collection.

If advanced endoscopic capabilities are available, an endoscopic retrograde cholangiopancreatogram (ERCP) is useful for diagnosis and treatment planning is useful since nearly all patients with pseudocysts have ductal abnormalities and sphincterotomy, stenting, or stricture dilation can be performed at the same time if indicated.

Walled-off Pancreatic Necrosis

Imaging will show a well encapsulated collection with debris. It may have loculations. Fluid sampling can be done and may have a high amylase if there is a connection with the pancreatic duct. Fluid sampling can also determine if the collection is infected.

Acute Necrotic Collection

Extraluminal gas seen in a collection in acute necrotic collections (or walled-off necrosis) suggests infection. In equivocal cases, fine needle aspiration (FNA) for culture may clarify presence or absence of infection, although most cases could be managed without FNA particularly if percutaneous drainage is pursued as part of management.

Complications

Generally, pseudocysts can cause compressive complications as a result of biliary obstruction, small bowel obstruction, or mesenteric venous thrombosis. They can also erode into nearby structures such as the small bowel, colon, or vasculature causing a fistula, pseudoaneurysm, or even significant bleeding. The pseudocyst can potentially rupture and cause pancreatic ascites, peritonitis, or even a pleuropancreatic fistula.

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