**4. Pathogenesis**

Several different procedures participate in the pathogenesis of the PPCs. In the cases that pseudocysts arise as a complication of severe acute pancreatitis, there is extravasation of pancreatic secretions due to disruption of the pancreatic duct. The gland necrosis leads to local fluid collection, which persists for more than 4 weeks as the inflammation recedes. Such pseudocysts usually contain enzymatic fluid and necrotic debris [8]. Concerning the pathogenesis of pseudocysts in chronic pancreatitis patients, at least two mechanisms may be involved. The cyst may develop as a consequence of progressive ductal obstruction by a protein plug, calculus, or localized fibrosis. In addition, a potentially acute exacerbation of the underlying disease can cause the cystic formation. Two-thirds of the patients with pseudocysts appear to have a connection between the pseudocyst and the pancreatic duct, while the rest do not have this exact finding and the cystic formation is caused due to the inflammatory reaction [9].
