Exocrine Pancreas Flashcards
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)
What do ductal cells secrete?
Water and sodium bicarbonate to wash the proteins from acinar cells down the ducts and into duodenum
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
Why doesn’t the pancreas undergo auto-digestion?
Inactive proenzymes (except for amylase and lipase)
Enzymes bound in zymogen granules
Trypsin inhibitors present
Acute Pancreatitis
What are the 2 main categories?
Acute interstitial pancreatitis (generally get full recovery)
Acute necrotizing and hemorrhagic pancreatitis (much more severe)
80% of Acute Pancreatitis is caused by…
Alcoholism
Biliary tract disease (obstruction)
Males vs. Females
What are the more likely causes of acute pancreatitis in each?
Males - Alcoholism
Females- Biliary tract disease
Why does alcoholism cause acute pancreatitis?
Alcohol activates hypersecretion of acinar cells and hyposecretion of water and bicarb by ductal cells
What are some metabolic disorders that could cause acute pancreatitis?
Hypertriglyceridemia
Hypercalcemia- Calcium activates enzymes
Hyperparathyroidism
What is an infectious process that can cause acute pancreatitis?
Mumps
3 mechanistic causes of acute pancreatitis (very general)…
Duct obstruction
Acinar Cell Injury
Defective intracellular transport
What are some clinical signs of acute pancreatitis?
Abdominal pain Elevated plasma amylase and lipase Diffuse fat necrosis and Hypocalcemia ARDS DIC
How does enzymatic fat necrosis occur? What does it result in?
Calcium combines with free fatty acids (called saponification) –> develop hypocalcemia
How is Acute Pancreatitis treated?
Address the underlying cause Supportive care -Analgesia -IV fluids -Correct electrolyte abnormalities -Restore oral intake when abdominal pain improves
How is chronic pancreatitis distinct from acute?
Permanent damage to the pancreas occurs
There is acinar cell atrophy and replacement by fibrotic tissue
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
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
