A 48-year-old male is admitted to the hospital with severe epigastric abdominal pain and vomiting after an episode of binge-drinking. Four weeks later, he is found to have a palpable upper abdominal mass and a cystic lesion is visualized on computed tomography scanning (see image below, asterisk marks the lesion). The inner walls of the lesion are most likely lined with:

Question

A 48-year-old male is admitted to the hospital with severe epigastric abdominal pain and vomiting after an episode of binge-drinking.  Four weeks later, he is found to have a palpable upper abdominal mass and a cystic lesion is visualized on computed tomography scanning (see image below, asterisk marks the lesion).  The inner walls of the lesion are most likely lined with:

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This CT image shows a pancreatic pseudocyst, a potential complication of pancreatitis. In acute pancreatitis, proteolytic enzymes may disrupt the walls of the pancreatic ducts and cause leakage of pancreatic secretions into the peripancreatic space. This fluid has a high pancreatic enzyme content and induces an inflammatory reaction in the walls of the surrounding organs. Granulation tissue forms, encapsulating the fluid collection and forming a pseudocyst. In contrast to a true cyst with walls lined by epithelial cells, the walls of a pseudocyst consist of granulation tissue and no epithelial lining. Fibrosis, thickening and organization of the walls occur with time. The formation of firm fibrotic pseudocyst walls ("maturation" of the pseudocyst) takes about 4 to 6 weeks following the episode of acute pancreatitis. The most common location for a pseudocyst is in the lesser peritoneal sac, bordered by the stomach, duodenum and transverse colon. The pseudocyst walls are closely adherent to the surrounding hollow organs. The pseudocyst in the CT image above is located in the lesser sac, posterior to the stomach. (Choice A) Glycogen-rich cuboidal epithelium is seen in serous pancreatic neoplasms. (Choice B) Columnar mucinous epithelium is typically found in mucinous cystic neoplasms of the pancreas. (Choice C) Atypical cells forming papillary projections are seen in the papillary variant of pancreatic adenocarcinoma. (Choice E) Endothelial cells are not found in the wall of the pseudocyst. Educational Objective: Pancreatic pseudocyst is a common complication of acute pancreatitis. It is a collection of fluid rich in enzymes and inflammatory debris. Its walls consist of granulation tissue and fibrosis. Unlike true cysts, pseudocysts are not lined by epithelium.

A 48-Year-Old Male Is Admitted to the Hospital with Severe