Pathology of exocrine pancreas

Question 1

Congenital abnormalities

Answer 1

• Ectopic pancreas: stomach, duodenum, jejunum, meckel’s, ileum
• Forms submucosal mass of disorganized acini, ducts, islets, fibrosis
• Maldevelopment of pancreas: divisum (failure of ventral and dorsal pancreases to fuse), annular pancreas (ring of pancreatic tissue around duodenum), congenital cysts
• Divisum predisposes to pancreatitis, annular pancreas can lead to bowel obstruction

Question 2

Acute pancreatitis

Answer 2

• Due to escape of activated pancreatic nzs into pancreatic parenchyma
• Causes necrosis (liquefactive), hemorrhage, inflammation, abscess formation, pseudocysts
• Fat necrosis (by lipase): grossly looks like chalky white foci around pancreas
• Calcification via Ca saponification in situ

Question 3

Chronic pancreatitis

Answer 3

• Chronic inflammation, fibrosis, dilation and stenosis of ducts
• Gross: diffuse or localized firm mass
• Micro: fibrosis, acinar atrophy, chronic inflammation, ductal stenosis and dilation, spared islets (until advanced), pseudocyst formation

Question 4

Autoimmune pancreatitis

Answer 4

• Lymphoplasmacytic sclerosing pancreatitis: IgG4 positive lymophoplasmacytic infiltrates
• Idiopathic duct-centric pancreatitis: mixed inflammatory infiltrates around ducts
• Can mimic malignancy but responds to steroids

Question 5

Cystic lesions of pancreas

Answer 5

• Pseudocysts: liquified areas of necrosis walled off by fibrous tissue and granulation, NO epithelial lining (thus pseudocyst)
• Complication of acute and chronic pancreatitis, solitary and unilocular
• Congenital cyst: rare, associated w/ other congenital diseases (PKD)
• Is a true cyst (epithelial lining)

Question 6

Neoplastic cysts 1

Answer 6

• Serous cystadenoma: benign, usually ASx, multi-locular w/ cuboidal serous epithelial lining and rich in cytoplasmic glycogen
• Mucinous cystadenoma: solitary, unilocular, large w/ tall columnar mucinous epithelial lining mucinous center (borderline malignant potential: atypia w/o invasion)
• Usually found in tail or body

Question 7

Neoplastic cysts 2

Answer 7

• Mucinous cystadenoCA: similar to cystadenoma but there is invasion and behaves like low grade malignancy
• Polarity of nuclei to base indicates benign (mucinous cystadenoma), no polarity and many mitoses indicates mutinous cystadenoCA (malignant)
• Intraductal papillary mucinous neoplasms (IPMNs): arise in main pancreatic duct, usually M, head of pancreas, may be benign, borderline, or malignant

Question 8

Pancreatic CA 1

Answer 8

• Vast majority are ductal adenoCA, minority are acinar cell CA
• Ductal adenoCA: M>F, blacks>whites, >50, most common in head (then tail)
• Etiology: due to mutations of KRAS, tumor suppressor genes (p53, p16, SMAD), PRSS1, cigarette increases risk
• Gross: firm infiltrative mass, usually smaller if in head and larger if in tail/body, causes distal obstruction of ducts
• CA in head tend to obstruct common bile duct early (tho they are small)

Question 9

Pancreatic CA 2

Answer 9

• Micro: neoplastic glands lined by cuboidal/columnar cells (mucinous and non-mucinous secreting), fibrosis
• Spread: infiltrates surrounding structures, perineural spread, LN spread, hematogenous spread to liver, lungs, bones
• Clinical: pain, jaundice (bile duct obstruction), constitutional Sx, anemia, thrombophlebitis of leg veins (trosseau syndrome) due to pro-coagulation factors
• Rx: only cure is total pacreaticduodenectomy (only early stages and in head), prognosis is poor