A 45-year-old man with a history of chronic alcohol use presents with persistent epigastric pain and early satiety 8 weeks after an episode of acute pancreatitis. Imaging reveals a well-circumscribed, round, anechoic fluid collection adjacent to the body of the pancreas with a thin enhancing wall and no mural nodules. The structure marked **B** in the diagram is identified. Which of the following best describes the defining pathological feature that distinguishes this lesion from a true pancreatic cyst?
A. Presence of a non-epithelialized fibrous and granulation tissue wall
B. Presence of a single layer of columnar epithelial lining
C. Presence of mucinous epithelium with mucin production
D. Presence of solid papillary components with nuclear atypia
Explanation
Why "Presence of a non-epithelialized fibrous and granulation tissue wall" is right
The defining feature of a pancreatic pseudocyst per the Revised Atlanta Classification 2012 is the absence of an epithelial lining. Instead, the cyst is surrounded by a non-epithelialized fibrous and granulation tissue wall that develops over 4–6 weeks following pancreatic duct rupture from inflammation or trauma. This lack of epithelial lining is precisely what makes it "pseudo" — distinguishing it from true cystic neoplasms (serous cystadenoma, mucinous cystic neoplasm, IPMN, solid pseudopapillary tumor), all of which have epithelial linings. The clinical presentation (persistent pain, early satiety, 8 weeks post-pancreatitis) and imaging findings (well-circumscribed, anechoic, thin wall, no nodules) are classic for a pseudocyst complicating chronic alcohol-related pancreatitis.
Why each distractor is wrong
Presence of a single layer of columnar epithelial lining: This describes a true pancreatic cyst (serous cystadenoma or other epithelial-lined cyst). Pseudocysts explicitly lack epithelial lining, making this the opposite of the defining feature.
Presence of mucinous epithelium with mucin production: This is characteristic of a mucinous cystic neoplasm (MCN) or IPMN, both of which have epithelial linings and produce mucin. Pseudocysts have no epithelium and low CEA (<192 ng/mL), whereas MCN/IPMN have high CEA.
Presence of solid papillary components with nuclear atypia: This describes a solid pseudopapillary tumor (SPT), a neoplastic cystic lesion with epithelial differentiation and potential malignancy. Pseudocysts contain only fluid and debris, with no solid or neoplastic components.
High-YieldNEET PG
Pseudocyst = no epithelium (fibrous/granulation wall only); True cyst = epithelial lining present (serous, mucinous, IPMN, SPT). This distinction is the cornerstone of cyst classification and guides management.
Revised Atlanta Classification 2012; ASGE/ESGE Pancreatic Cyst Guidelines
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