Pathology of the exocrine pancreas

EXOCRINE PANCREAS

OBJECTIVES
Understand the aetiology
Risk factors,
Pathogenesis,
Morphology,
Clinical features and
Outcome of pancreatic inflammations and neoplasms

L2

PANCREAS

Arterial supply and venous drainage of the pancreas and spleen

Lymphatic drainage of the distal pancreas and spleen
“Peri-”pancreatic lymph nodes, several groups.

Hepaticopancreatic ampulla
(Ampulla of Vater)

Pancreatic Enzymes
Amylase
Lipase
DNA-ase
RNA-ase
Zymogens: Trypsinogen Chymotrypsinogen Procarboxypeptidase A, B

PANCREAS DISEASES
Congenital
Inflammatory
Acute
Chronic
Cysts
Neoplasms

Congenital
Agenesis (very rare)
Annular Pancreas (pancreas encircles duodenum) (rare)
Pancreas Divisum (failure of 2 ducts to fuse) (common)
Ectopic Pancreatic tissue (very common)
Cysts

PANCREATITIS
ACUTE (VERY SERIOUS)
CHRONIC (Calcifications, Pseudocyst)

ACUTE PANCREATITIS
Idiopathic:
Gallstones (45%)
Ethanol (35%)
Tumours: pancreas, ampulla,
Scorpion stings
Microbiological ƒ.bacterial: ƒ.viral: (mumps, varicella) ƒ.parasites: Autoimmune: SLE, polyarteritis nodosa (PAN), Crohn’s
Surgery/trauma
abdomen, penetrating peptic ulcer
Hyperlipidemia (TG >11.3 mmol/L; >1000 mg/dL), Hyperparathyroidism Hypercalcemia, Hypothermia
Emboli or ischemia
Drugs/toxins, estrogens, methyldopa, H2-blockers

GALL STONES
MUMPS VIRUS
COMMON CAUSES OF PANCREATITIS
PANCREATITIS

Pathogenesis
Activation of proteolytic enzymes within pancreatic cells, starting with trypsin, leading to local and systemic inflammatory response
• In gallstone pancreatitis, this is due to mechanical obstruction of the pancreatic duct by stones
• In ethanol-related pancreatitis, pathogenesis is unknown
Mutations prevent the physiological breakdown of trypsin

MORPHOLOGY
OEDEMA
FAT NECROSIS
“SAPONIFICATION”
ACUTE INFLAMMATORY INFILTRATE
PANCREAS AUTODIGESTION
BLOOD VESSEL DESTRUCTION

CLINICAL FEATURES
• Pain: epigastric, noncolicky, constant can radiate to back
• May improve when leaning forward (inglefinger’s sign)
• Tender rigid abdomen; guarding
• Nausea and vomiting
• Abdominal distention from paralytic ileus
• Fever: chemical, not due to infection
• Jaundice: compression or obstruction of bile duct
• Tetany: transient hypocalcemia
• Hypovolemic shock: can lead to renal failure
• Acute respiratory distress syndrome
• Coma

Repeated episodes of clinically evident acute pancreatitis
Common cause is alcohol
Autoimmune pancreatitis
Cystic fibrosis
Familial pancreatitis
Aminoaciduria or hyperparathyroidism
Fibrosis & exocrine atrophy
May results in intestinal malabsorption
CHRONIC PANCREATITIS

CLINICAL FEATURES
Abdominal Pain
Vague abdominal symptoms
chronic diarrhea(mal absorption)
DM
pseudocysts
amylase elevated, or normal

Investigations
• laboratory:
ƒ. increase in serum glucose
ƒ. increase in serum ALP, less commonly bilirubin (jaundice)
ƒ. Serum amylase
• Radiology: looking for pancreatic calcifications
• U/S or CT: calcification, dilated pancreatic ducts, pseudocyst
• MRCP or ERCP: abnormalities of pancreatic ducts-narrowing and dilatation
• • 72-h fecal fat test: measures exocrine function
• secretin test: gold standard, measures exocrine function but difficult to perform, unpleasant for the patient, expensive
• fecal pancreatic enzyme measurement (elastase-1, chymotrypsin) available only in selected centres

Management
• pain, difficult to control
• general management:
ƒ. total abstinence from alcohol
ƒ. enzyme replacement may help pain by resting pancreas via negative feedback analgesics - celiac ganglion blocks
• endoscopy: sphincterotomy, stent if duct dilated, remove stones from pancreatic duct
surgery: drain pancreatic duct (resect pancreas if duct contracted
• ƒ. restrict fat,
increase carbohydrate and protein (may also decrease pain)

Cysts & Cystic tumours
Pancreatic cysts are of two types
True cysts which are lined by epithelium and may be congenital
Pseudocyst which lacks an epithelial lining and are usually the result of acute pancreatitis and can be drained surgically
True cystic tumours also occur as benign cystadenoma & malignant cystadenocarcinoma

ACUTE PANCREATITIS
CHRONIC PANCREATITIS
SYSTEMIC ORGAN FAILURE
SHOCK
ARDS
ARF
DIC
PANCRATIC ABCESSES
PANCREATIC PSEUDOCYST
DOUDENAL OBSTRUCTION
PSEUDOCYST
DUCT OBSTRUCTION
MALABSORPTION STEATORRHEA
SECONDARY DIABETES
CONSEQUENCES of ACUTE and CHRONIC pancreatitis

CARCINOMA OF THE PANCREAS
USUALLY ADENOCARCINOMA
MAY PRESENT WITH OBSTRUCTIVE JAUNDICE
VERY POOR PROGNOSIS
AETIOLOGY
CIGARETTE SMOKING
DM
FAMILIAL PANCREATITIS
WEIGHT LOSS
SYMPTOMS ATTRIBUTABLE TO THE LOCATION OF THE TUMOUR

CLINICOPATHOLOGICAL FEATURES
MOST ARE ADENOCARCINOMA
MOST COMMONLY ARISE IN THE HEAD OF THE PANCREAS
COMPRESS THE COMMON BILE DUCT & CAUSE OBSTRUCTIVE JAUNDICE
EXTENSIVE REPLACEMENT BY CARCINOMA CAN LEAD TO DM.
SPREAD BY LYMPH & BLOOD TO THE LIVER

Pancreatic
Adenocarcinoma

REMEMBER
Painless jaundice in an elderly person is CARCINOMA of the head of the pancreas until proven otherwise