Pancreatic Pseudocyst
Basics
- A pancreatic pseudocyst is a peripancreatic (or intrapancreatic) fluid collection associated with a history of pancreatitis, that is surrounded by a well-defined inflammatory wall and that has no solid component.
- The term “pseudocyst” is often incorrectly used to define various types of fluid collections associated with pancreatitis. As a result, medical literature on pseudocysts is not consistent in its descriptions or its findings.
- An important distinction between “fluid collections” associated with pancreatitis is that some consist of fluid alone, whereas others arise from necrosis of pancreatic parenchyma and/or peripancreatic tissues. The latter type of fluid collection involves a solid component (with variable amounts of fluid), which distinguishes them from pseudocysts.
- Types of fluid collections:
- Acute peripancreatic fluid collection (APFC)
- A fluid collection that develops in the early phase of interstitial edematous acute (typically mild) pancreatitis
- Lack a well-defined wall on CT scan
- Not associated with necrotizing pancreatitis
- Remains sterile and usually resolves without intervention
- If APFC persists beyond 4 weeks, likely to develop into a pancreatic pseudocyst, although this is considered a rare outcome
- Pancreatic pseudocyst
- Refers specifically to a peripancreatic (or less commonly, an intrapancreatic) fluid collection
- Surrounded by a well-defined inflammatory wall and containing no solid material
- Pancreatic pseudocysts develop >4 weeks after the onset of interstitial pancreatitis.
- Acute necrotic collection (ANC)
- A collection of both variable amounts of fluid and solid (necrotic) material related to pancreatic and/or peripancreatic necrosis
- Occur within the first 4 weeks of disease and can resemble an APFC in the first few days of acute pancreatitis
- As necrotizing pancreatitis develops and necrosis evolves, solid component become evident.
- May be multiple and may involve the pancreatic parenchyma alone, the peripancreatic tissue alone, or most commonly both
- May be infected or sterile
- Generally associated with more severe sequelae of acute pancreatitis
- Walled-off necrosis (WON)
- Collection of varying amounts of liquid and solid material surrounded by a mature, enhancing wall of reactive tissue
- Represents a mature, encapsulated ANC
- Develops no earlier than 4 weeks after episode of necrotizing pancreatitis
- May be multiple and present at sites distant from the pancreas
- May be sterile or infected
- Acute peripancreatic fluid collection (APFC)
Pathophysiology
- Pseudocysts occur when there is disruption in the pancreatic ductular system, or its intrapancreatic branches, without any evidence of pancreatic or peripancreatic necrosis.
- This results in the extravasation of pancreatic enzymes evoking an inflammatory response.
- The inflammatory reaction leads to a fluid collection that is rich in pancreatic enzymes (APFC).
- If the duration of the fluid collection is >4 weeks, becomes localized (intrapancreatic or extrapancreatic), and develops a fibrin capsule, it becomes a pseudocyst.
- A pseudocyst does not have a true epithelial lining.
- If there is communication between the pseudocyst and the pancreatic duct, the enzyme level in the fluid remain elevated; if there is no communication, the enzyme level falls with time.
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Citation
Cabana, Michael D., editor. "Pancreatic Pseudocyst." 5-Minute Pediatric Consult, 8th ed., Wolters Kluwer, 2019. Pediatrics Central, peds.unboundmedicine.com/pedscentral/view/5-Minute-Pediatric-Consult/617176/all/Pancreatic_Pseudocyst.
Pancreatic Pseudocyst. In: Cabana MDM, ed. 5-Minute Pediatric Consult. Wolters Kluwer; 2019. https://peds.unboundmedicine.com/pedscentral/view/5-Minute-Pediatric-Consult/617176/all/Pancreatic_Pseudocyst. Accessed December 9, 2024.
Pancreatic Pseudocyst. (2019). In Cabana, M. D. (Ed.), 5-Minute Pediatric Consult (8th ed.). Wolters Kluwer. https://peds.unboundmedicine.com/pedscentral/view/5-Minute-Pediatric-Consult/617176/all/Pancreatic_Pseudocyst
Pancreatic Pseudocyst [Internet]. In: Cabana MDM, editors. 5-Minute Pediatric Consult. Wolters Kluwer; 2019. [cited 2024 December 09]. Available from: https://peds.unboundmedicine.com/pedscentral/view/5-Minute-Pediatric-Consult/617176/all/Pancreatic_Pseudocyst.
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