KEY FACTS
Terminology
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Collection of pancreatic fluid and inflammatory exudate encapsulated by nonepithelial fibrous tissue developing > 4 weeks after acute pancreatic fluid collection
Imaging
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2/3 are peripancreatic: Body and tail (85%)
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Uncomplicated pseudocyst: Well-defined, unilocular, peripancreatic cystic mass in setting of prior pancreatitis
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Smooth-walled, posterior acoustic enhancement
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1/3 extrapancreatic
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In addition to peripancreatic space, other locations, such as peritoneal space, intraabdominal parenchyma, and intrathoracic cavity, should also be evaluated
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Complex pseudocysts: Fluid-debris level, internal echoes, or septations (due to hemorrhage/infection); multilocular
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Develops over 4-6 weeks from acute pancreatic fluid collection
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CT best to evaluate extent of pseudocyst and complications
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Gas within pseudocyst: Infection vs. decompression into stomach or bowel
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MRCP helpful to visualize communication with pancreatic duct
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Dilated pancreatic duct and common bile duct
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Wall calcification
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Absence of internal blood flow
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Endoscopic ultrasound may be required for aspiration and histologic diagnosis
Top Differential Diagnoses
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Mucinous or serous cystic neoplasm
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Intraductal papillary mucinous neoplasm
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Cystic islet cell tumor
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Choledochal cyst
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True epithelial cysts
Pathology
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Collection of fluid, tissue, debris, pancreatic enzymes, and blood covered by thin rim of fibrous capsule
Clinical Issues
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Associated with acute or chronic pancreatitis; alcoholism, cholelithiasis/choledocholithiasis
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Chronic alcoholism (75%)
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Clinical significance is related to size and complications; however, may be asymptomatic
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Abdominal pain, typically radiating to back; palpable tender mass
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Complications: More common in pseudocysts > 4-5 cm
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Spontaneous rupture into peritoneal cavity
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Erosion into adjacent vessel causing pseudoaneurysm or hemorrhage
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Compression of adjacent bowel or bile duct
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Fistula to stomach or bowel
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Spontaneous resolution in 25-40% of patients
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Rupture and hemorrhage are prime causes of death from pseudocyst
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Conservative therapy if asymptomatic or decreasing in size
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Percutaneous drainage required when symptomatic or enlarging
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Curative in 90% of cases
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Scanning Tips
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Turn on color Doppler to look for pseudoaneurysm or active bleeding in pseudocyst
in the pancreatic body consistent with a pancreatic pseudocyst. The adjacent pancreatic duct is not compressed or displaced.
. Posterior acoustic enhancement 
is noted. The spleen 
provides an acoustic window.
. There is posterior acoustic enhancement 
. Calcification in the wall 
is a sign of chronic pancreatitis.
