Acute pancreatitis: morphology and complications
- Lesion
Mild pancreatitis only swells the gland; severe pancreatitis kills tissue and fat, bleeds and can lead to infection and cysts.
What it is
The morphology of acute pancreatitis ranges from interstitial edema with focal fat necrosis to necrotizing pancreatitis with destruction of acinar, ductal and islet tissue, and hemorrhagic pancreatitis with bleeding into the gland. The basic lesions are microvascular leakage with edema, fat necrosis from lipases, acute inflammation, proteolytic destruction of parenchyma and destruction of vessels. Local and systemic complications decide the outcome.
Structure
- Gross: swollen gland with red-black hemorrhage and chalky yellow-white fat necrosis in the peripancreatic fat.
- Micro: interstitial edema, fat necrosis with ghostly fat cells and basophilic calcium soaps, neutrophils, necrotic acini, vessel walls destroyed with hemorrhage.
Step by step
- Activated enzymes injure small vessels: plasma leaks and the gland swells.
- Lipase releases fatty acids from fat cells; they bind calcium: chalky fat necrosis.
- Neutrophils arrive and release more proteases and oxidants.
- Elastase dissolves vessel walls: bleeding into gland and retroperitoneum.
- Necrotic tissue may become infected or walled off by granulation tissue into a pseudocyst.
Mild vs severe acute pancreatitis
| Feature | Interstitial edematous | Necrotizing or hemorrhagic |
|---|---|---|
| Gland | Swollen, intact parenchyma | Necrotic parenchyma, hemorrhage |
| Fat necrosis | Focal | Extensive, peripancreatic and distant |
| Imaging | Uniform enhancement | Non-enhancing necrotic areas |
| Complications | Few | Infected necrosis, pseudocyst, organ failure |
| Course | Recovery in days | Prolonged, mortality significant |
In the lab
- Lipase is more specific and stays raised longer than amylase.
- Hypocalcemia, hyperglycemia and raised hematocrit or urea are signs of severity.
Test yourself
Think of the answer, then tap the question to see it.
What gives fat necrosis its chalky white appearance?
Fatty acids released by lipase combine with calcium to form soaps (saponification).
What are Cullen and Grey Turner signs?
Periumbilical (Cullen) and flank (Grey Turner) bruising from retroperitoneal hemorrhage in severe pancreatitis.
Which enzyme causes the vascular damage and hemorrhage in severe pancreatitis?
Elastase, which digests elastic fibres of vessel walls.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Acute Pancreatitis (StatPearls (NCBI Bookshelf), 2025); Pancreatic pseudocyst: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026).
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Representative model, for educational purposes only.