What is interstitial pancreatitis?

Interstitial Pancreatitis

Interstitial pancreatitis (also called acute interstitial pancreatitis or edematous pancreatitis) is the mild form of acute pancreatitis characterized by interstitial edema of the pancreatic gland without tissue necrosis, associated with minimal organ dysfunction and an uneventful recovery. 1

Pathological Features

• The predominant pathological feature is interstitial edema of the gland, distinguishing it from necrotizing pancreatitis which involves tissue death 1, 2
• The inflammatory process includes parenchymal edema and inflammatory cell infiltration, but critically lacks acinar cell necrosis 3, 4
• Interstitial pancreatitis accounts for 90-95% of all acute pancreatitis cases, with necrotizing pancreatitis comprising only the remaining 5-10% 5

Clinical Characteristics

• Patients present with minimal organ dysfunction and typically have an uneventful recovery without complications 1, 2
• The disease process is completely reversible with evident normal tissue architecture after recovery, unlike chronic pancreatitis which causes irreversible damage 4
• Diagnosis is typically made based on clinical findings, elevated lipase levels, and imaging, though rare cases can occur with normal lipase 6

Imaging and Differentiation

• CT is used to differentiate acute interstitial pancreatitis from necrotizing pancreatitis, which is a key element of modern classification systems 5
• IV contrast-enhanced CT performed 40 seconds after injection is the optimal timing to assess for necrosis 5
• On imaging, interstitial pancreatitis shows pancreatic edema without areas of non-enhancement that would indicate necrosis 5

Associated Fluid Collections

• Acute peripancreatic fluid collections (APFCs) may develop within approximately 4 weeks of onset in interstitial pancreatitis 5
• These collections always lack a wall of granulation or fibrous tissue initially 1, 7
• If a collection persists beyond 4 weeks and develops a thin wall, it is termed a pseudocyst 5
• More than half of acute fluid collections resolve spontaneously and do not require treatment in otherwise stable patients 7

Clinical Significance

The distinction between interstitial and necrotizing pancreatitis is critical because:

• Interstitial pancreatitis carries a much better prognosis with minimal mortality risk 1
• Necrotizing pancreatitis, particularly when infected, triples the mortality risk 1, 2
• Management strategies differ significantly, with interstitial pancreatitis typically requiring only supportive care rather than intensive monitoring or interventional procedures 1