Pancreatic pseudocyst pathophysiology

Pancreatic Pseudocyst, also known as “false cyst” as they do not have true epithelial lining. The pathophysiology of pancreatic pseudocyst involves trauma or episode of pancreatitis followed by extravasation of pancreatic secretions.

If acute pancreatitis persists more than 4-6 weeks and is seen with a wall of fibrous or granulation tissue which is well-defined, it is called formation of a pseudocyst due to acute pancreatitis which is filled with enzymatic fluid and necrotic debris.

The formation of pancreatic pseudocyst due to chronic pancreatitis is less well understood. It is still believed tp occur either due to episode of acute exacerbation in chronic pancreatitis and/or blockage of pancreatic duct by protein plug or calculus or localized fibrosis.^[1]

Acute pancreatitis results amongst other things in the disruption of pancreatic parenchyma and the ductal system. This results in extravasation of pancreatic enzymes which in turn digest the adjoining tissues. This results in a collection of fluid containing pancreatic enzymes, hemolysed blood and necrotic debris around the pancreas. The lesser sac being a potential space, the fluid collects here preferentially. This is called an acute pancreatic collection. Some of these collections resolve on their own as the patient recovers from the acute episode. However, others become more organised and get walled-off within a thick wall of granulation tissue and fibrosis. This takes several weeks to occur and results in a pancreatic pseudocyst.

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