Which condition involves the accumulation of pancreatic fluid outside the pancreas in a cystic structure?

The accumulation of pancreatic fluid outside the pancreas in a cystic structure is characteristic of a pseudocyst. A pseudocyst is a common complication of acute or chronic pancreatitis, where the enzymatically active fluid that leaks from the damaged pancreas becomes encapsulated by a fibrous tissue wall. Unlike true cysts, pseudocysts do not have an epithelial lining; instead, they are typically formed by a collection of fluid rich in pancreatic enzymes, inflammatory mediators, and debris.

In contrast, cystic fibrosis primarily affects the lungs and causes thick mucus buildup in various organs but is not defined by localized pancreatic fluid accumulation in cystic structures. Pancreatic necrosis refers to the death of pancreatic tissue that can occur due to severe pancreatitis, but it involves tissue destruction rather than fluid accumulation in a defined cystic form. Edematous pancreatitis, while it may present with swelling of the pancreas due to inflammation, does not specifically refer to the formation of a cystic structure filled with fluid as seen in pseudocysts. Therefore, the unique characteristics of pseudocysts make it the correct answer regarding pancreatic fluid accumulation outside the pancreas.