Extra-pancreatic necrosis alone: Contours of an emerging entity

Acute pancreatitis is of two morphologic types: interstitial edematous pancreatitis that is not associated with any tissue necrosis and necrotizing pancreatitis wherein the pancreatic parenchyma with or without varying amount of extra-pancreatic tissue/fat undergoes necrosis. Necrotizing pancreatitis has a worse outcome compared with interstitial pancreatitis because of increased severity related to a heightened systemic response and cytokine storm associated with tissue necrosis. Increasingly, an entity of extra-pancreatic necrosis (EPN) alone, wherein the pancreatic parenchyma is normal on an enhanced computed tomographic scan but the peri-pancreatic tissues undergo necrosis, is being recognized. Available data suggest that the outcomes in patients with EPN alone are between the excellent prognosis of patients with interstitial and adverse prognosis of patients with necrotizing pancreatitis. The extent of EPN also seems to determine the outcome. This review summarizes the currently available literature on this entity and various radiological scores that have been suggested to determine the presence and stage of EPN.