Exocrine Pancreas Flashcards by Tom O

Describe the appearance of the acinar cells of the pancreas

Pyramidally shaped epithelial cells oriented radially around central lumen

Cuboidal epithelium
Basal nuclei with often prominent nucleoli
Granular cytoplasm (zymogen granules)

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What do ductal cells secrete?

Water and sodium bicarbonate to wash the proteins from acinar cells down the ducts and into duodenum

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The pancreas largely makes proenzymes (like trypsinogen) to prevent auto-digestion, but two enzymes are made in their active form. What are they?

Amylase and Lipase

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Why doesn’t the pancreas undergo auto-digestion?

Inactive proenzymes (except for amylase and lipase)

Enzymes bound in zymogen granules

Trypsin inhibitors present

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Acute Pancreatitis

What are the 2 main categories?

Acute interstitial pancreatitis (generally get full recovery)

Acute necrotizing and hemorrhagic pancreatitis (much more severe)

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80% of Acute Pancreatitis is caused by…

Alcoholism

Biliary tract disease (obstruction)

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Males vs. Females

What are the more likely causes of acute pancreatitis in each?

Males - Alcoholism

Females- Biliary tract disease

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Why does alcoholism cause acute pancreatitis?

Alcohol activates hypersecretion of acinar cells and hyposecretion of water and bicarb by ductal cells

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What are some metabolic disorders that could cause acute pancreatitis?

Hypertriglyceridemia

Hypercalcemia- Calcium activates enzymes

Hyperparathyroidism

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What is an infectious process that can cause acute pancreatitis?

Mumps

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3 mechanistic causes of acute pancreatitis (very general)…

Duct obstruction

Acinar Cell Injury

Defective intracellular transport

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What are some clinical signs of acute pancreatitis?

Abdominal pain
Elevated plasma amylase and lipase
Diffuse fat necrosis and Hypocalcemia
ARDS
DIC

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How does enzymatic fat necrosis occur? What does it result in?

Calcium combines with free fatty acids (called saponification) –> develop hypocalcemia

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How is Acute Pancreatitis treated?

Address the underlying cause
Supportive care
-Analgesia
-IV fluids
-Correct electrolyte abnormalities
-Restore oral intake when abdominal pain improves

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How is chronic pancreatitis distinct from acute?

Permanent damage to the pancreas occurs

There is acinar cell atrophy and replacement by fibrotic tissue

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What are some causes of chronic pancreatitis?

Alcoholism (long term abuse)

Long standing obstruction

Hereditary (genes involving trypsinogen activators or trypsin inhibitors)

Cystic fibrosis

Tropical pancreatitis

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Describe the histological appearance of chronic pancreatitis

Fibrosis
Loss of acinar cells
Dilated pancreatic ducts
Destruction of islets of Langerhans (late stage- leads to diabetes)
May see ductal calcifications

Symptoms of Chronic Pancreatitis

Recurrent attacks abdominal pain, radiating to back

Recurrent jaundice or indigestion

Exocrine pancreas insufficiency- steatorrhea

Diabetes

Pancreatic calcifications on imaging

Pancreatic Pseudocysts

What are they caused by? What is their histological appearance?

Caused by acute or chronic pancreatitis

Histology-
No true epithelial lining
Chronic inflammation and granulation tissue

Pancreatic Carcinoma

Pathogenic factors

Pancreatic intraepithelial neoplasia (PanIN)
Smoking
Genetics
Chronic pancreatitis
Diabetes

More than 90% of pancreatic cancer is associated with a gene mutation in….

K-RAS

What other mutations (besides KRAS) may be involved in pancreatic carcinoma?

p16
p53
BRCA2
SMAD4

What kind of cancer is pancreatic carcinoma?

Infiltrating ductal Adenocaricnoma

Where in the pancreas are carcinomas most commonly located?

Head (60%)
Body (15%)
Tail (5%)
Diffuse (20%)

In response to the tumor, the pancreas may undergo a dense stromal fibrosis classified as a....

Desmoplastic Response

Common organs for distant metastases of pancreatic cancers

Liver Lungs Bones

Pancreatic Carcinoma | What are the presenting symptoms?

Mostly asymptomatic until they impinge on other structures ``` Back pain - perineural invasion Obstructive jaundice Weight loss Anorexia Malaise ```

Pancreatic Carcinoma | What are some tumor markers used to monitor?

CA19-9 and CEA in peripheral blood Sensitive, but not very specific More often used for monitoring post resection

Pancreatic Carcinoma | What is obstructive jaundice?

Tumor obstructs the ampullary region/common bile duct. Prevents conjugated bile from entering duodenum, increasing pressure in biliary tract and forcing conjugated bile to enter the bloodstream

Pancreatic Carcinoma | What is migratory thrombophlebitis?

Known as Trousseau sign Venous thromboses that spontaneously appear and disappear Attributed to procoagulants released by the tumor

Pancreatic Carcinoma | What may be done to relieve obstructive jaundice?

Place a stent in the duct to keep it open

What is the Whipple procedure?

For tumors in the head or neck of pancreas, this procedure is a pancreaticoduodenectomy

Serous Cystadenoma | Appearance

Totally benign Small cysts lined by glycogen-rich cuboidal cells Release clear fluid

Serous Cystadenoma | Treatment

Benign, so no treatment needed unless it is impinging on other organs

Pancreatic Mucinous Cystadenoma | Appearance

Cysts filled with thick mucin | More often seen in body/tail of pancreas

Pancreatic Mucinous Cystadenoma | What are the risks?

Potential for malignant transformation (into a pancreatic mucinous cystadenocarcinoma)

Pancreatic Mucinous Cystadenoma | Who is the typical patient?

Female

Intraductal Papillary Mucinous Neoplasm (IPMN) | Where does it appear? Who is the typical patient?

Arises in main pancreatic duct or its major branch Commonly in pancreatic head Men more common than women

Agenesis of pancreas is likely due to what mutation?

PDX1 gene mutation

Annular Pancreas | Describe the pathology

Pancreas head wraps around duodenum, causing obstruction

Pancreas Divisum | Describe the pathology

Duct system within the pancreas does not fuse Pancreatic secretions cannot easily reach duodenal lumen Can cause chronic obstruction and chronic pancreatitis

Ectopic Pancreas | Describe the pathology

Pancreas tissue seen in other organs (such as stomach, duodenum, jejunum, ileum) Likely asymptomatic, but may cause bleeding, pain Can cause acute/chronic inflammation of pancreatic adenocarcinoma