Acute Pancreatitis

Question 1

Definition and aetiology of acute pancreatitis

Answer 1

Definition:
Reversible, acute inflammation of exocrine pancreas due to parenchymal injury

Aetiology :
1. Metabolic.
~ alcohol
~ hyper lipoproteinemia
~ hyperparathyroidism
~ hypercalcaemia

2. Mechanical.
   ~ Gall stones
   ~ pancreatic cancer
   ~ blunt trauma
   ~ Iatrogenic surgery
   ~ ascaris lumbricoides, Clonorchis sinensis, mumps, Coxsackie virus
3. Drugs and toxins
   ~ furosemide, azathioprine
   ~ OP , methanol, insecticides
4. Genetic
   ~ mutations of PRSS1, SPINK1 gene
5. Vascular.
   ~ shock
   ~ atherosclerosis
   ~ thromboembolism
   ~ vasculitis
6. Idiopathic

Question 2

Pathogenesis of acute pancreatitis

Answer 2

Premature activation of proteolytic pancreatic enzymes- auto digestion

~ trypsinogen, chymotrypsinogen, proelastase, phospholipase A2 —> enzyme
~ premature- before secretion from acinar cells
~ activation of trypsin from trypsinogen - triggering event
~ factors that trigger; endotoxin, exotoxin, viral infections, ischaemia, anoxia
~ Trypsin converts pro enzymes into active enzymes
~ trypsin activates prekallikrein - kallikrein - activate factor 12- activates compliment and clotting system

1. Pancreatic duct obstruction: tumour
   ~ raise intraductal pressure- rupture of ductules and acini- liberates enzyme which fluid- activation of proenzymes- injury- local inflammation- interstitial edema - ischaemic injury
2. Primary acinar cell injury
   ~ trigger: virus, drugs, alcohol, trauma
   ~ initiate inflammation- pancreatic Edema - haemorrhage- necrosis
3. Defective intra cellular transport of proenzymes
   ~ fusion of lysosome and enzymes within large vacuoles- activates proenzymes

Mechanism of alcohol induced pancreatitis
1. Obstruction of small ductules by proteinaceous plugs
2. Abnormal spasm of sphincter of Oddi
3. Direct toxic effects on acinar cells
4. Increased proteases in pancreatic secretion

Question 3

Clinical features and complications of acute pancreatitis

Answer 3

Clinical features
~ abdominal pain: intense, constant, referred to upper back
~ anorexia, nausea, vomiting

Complications
1. Local.
~ sterile pancreatic abscess
~ pancreatic pseudocyst
~ infection by gram negative bacteria

2. Systemic
   ~ shock+ acute renal tubular necrosis
   ~ ARDS
   ~ acute renal failure
   ~ haemolyses
   ~DIC
   ~Fat necrosis

Question 4

Laboratory findings of acute pancreatitis

Answer 4

~ leucocytosis
~ serum amylase elevated- 24h
~ serum lipase elevated: 72-96h
~ glycosuria
~ hypocalcaemia
~ direct visualisation by radiography

Question 5

Morphology of acute pancreatitis

Answer 5

1. Interstitial or edematous pancreatitis
   ~ mild and reversible
   ~ interstitial edema + infiltration by polymorphonuclear leucocytes
2. Acute necrotising pancreatitis
   Gross :
   Pancreas
   ~enlarged, swollen, red black areas ofhaemorrhage, yellow white chalky fat necrosis
   ~ fatty acids+ calcium- insoluble salts (saponification)
   Extra patriotic lesions
   ~ foci of fat necrosis - omentum and mesentry of bowel
   ~ Peripancreatic tissue - serous, turbid, brown fluid- Fat globules: Putty like/ canned dog food

Micro:
~ interstitial edema
~ acute inflammation
~ enzymatic fat necrosis: granular blue+ ghost outlines
~ destruction of parenchyma- proteolytic digestion
~ destruction of blood vessels- due to activated elastase- interstitial haemorrhage

3. Acute haemorrhagic pancreatitis.
   ~ middle age,high morbidity mortality
   ~ extensive necrosis +haemorrhage
   ~ large retroperitoneal haematoma