RADIOLOGY: PANCREAS: Case# 32889: PANCREATIC PSEUDOCYST. A 41 year old man with recent history of pancreatic necrosis secondary to pancreatitis. There is a large, homogeneous fluid collection replacing most of the head, body and tail of the pancreas. Pancreatic pseudocysts are usually the sequelae of pancreatitis, most often associated with the subacute or chronic varieties. Peripancreatic fluid collections in the setting of acute pancreatitis are not pseduocysts. A pseudocyst is a cystic structure with a thick, fibrous wall and is not lined with epithelium (hence, it is not a true cyst). A pseudocyst may have a persistent connection to the pancreatic duct which may be demonstrated by ERCP. Typically, an uncomplicated pseudocyst will have a homogeneous water density. Increased density or inhomogeneity indicate some complicating factor such as hemorrhage or infection. Psuedocysts may also form in the walls of bowel (stomach, duodenum, colon) due to extension of pancreatic enzymes into the surrounding tissues.