In which type of pancreatitis does inflammation extend outside the pancreas?

Phlegmonous pancreatitis is characterized by diffuse inflammation that extends beyond the pancreatic tissue itself. This form of pancreatitis involves not only the pancreas but also the surrounding peritoneal tissue. The inflammatory process can lead to the formation of edematous and necrotic areas in adjacent tissues, which may manifest as fluid collections or even abscesses. This extensive involvement is crucial for distinguishing phlegmonous pancreatitis from other types, which may be more localized.

In contrast, pseudocyst pancreatitis primarily refers to the formation of a fluid-filled cavity (pseudocyst) in response to pancreatic inflammation, but it does not indicate inflammation extending outside the pancreas. Edematous pancreatitis usually describes the early phase of inflammation where swelling occurs within the pancreas itself without extensive peritoneal involvement. Chronic pancreatitis involves long-standing inflammation that leads to structural changes but is typically more confined to the pancreas rather than spreading into surrounding tissue. Thus, phlegmonous pancreatitis is the correct choice for this scenario due to its characteristic extent of inflammation.