Pancreatic Pathology

Pancreatic Pathology Exocrine Pancreas • Retroperitoneal organ, pancreatic length 20cm, mass 60-140g. • Exocrine 85% of mass • 2/3 adults – pancreatic duct drains to CBD proximal to ampulla of Vater • 1/3 – pancreatic duct separately to duodenum • Nonpalpable, unless duct obstruction occurs, tumors may be large at presentation (poor prognosis) • Composed of acini (nests) and ducts • Acini cuboidal to columnar cells w/cytoplasmic zymogen granules • Ducts are lined by columnar epithelium • Fat, alcohol stimulate secretin, cholecystokinin production • These stimulate 1.5-3L of alkaline enzyme containing fluid per day

Exocrine pancreas

Congenital Abnormalities • Agenesis: Rare, usually associated w/multiple congenital abnormalities • Annular pancreas: Encircles duodenum causing partial obstruction o Classic presentation: recurrent bilious vomiting (because obstruction is often distal to where CBD drains) • Pancreas divisum: Incomplete fusion, predisposes to chronic pancreatitis o Embryologic origin of pancreas – two separate glands that normally fuse (not here) • Ectopic pancreas: 2% incidence, stomach, duodenum, Meckel’s diverticulum Test q: An otherwise healthy 3M has occasional episodes of bilious (bile-containing) vomiting that have become progressively more frequent. What abnormality of the pancreas should be considered? Annular pancreas. (Other choices: Pancreas divisum, Pancreatic agenesis, Pancreatic heterotopia involving the stomach)

Acute pancreatitis • 80% associated w/biliary tract disease (most commonly gall stone disease) or alcoholism o Gall stones travel down the cystic duct into the CBD and can become lodged at the ampulla, block drainage from pancreatic duct • Presents w/abdominal pain, elevated amylase (at 1 day), elevated lipase (at 3 days) • May result in shock, ARDS (life-threatening complications) • May develop fat necrosis, hemorrhage, abscess, pseudocyst o When the pancreatic ducts are damaged, amylase and lipase can leak out into the tissue and cause necrosis of the tissue (especially fat). o The necrotic fat may actually calcify/saponify. Figure: Fat necrosis in acute pancreatitis  Figure: Pancreatic pseudocyst. Fibrosis around it  Pseudocyst lacks epithelial lining, has inflammatory cells, protein-containing fluid. Late stage of pancreatitis – necrosis  liquefies into cyst-like space. Test q: Which 2 situations account for 80% of cases of acute pancreatitis? Gallstones and alcohol. (Other choices: Pancreatic adenocarcinoma and adenomas of the ampulla of Vater, Trauma and DIC, IV contrast administration and cholesterol emboli.) REPEATED x2 Test q: A 39M presents w/severe epigastric pain and hypotension. Serum amylase and lipase are markedly elevated. The most important etiologies to consider in this situation are: Alcohol and gallstones. (Other choices: Trauma and autoimmune, Adenocarcinoma and intraductal papillary mucinous tumor, α-1-antitrypsin deficiency and Wilson’s disease, Helicobacter and celiac sprue.) Test q: A 42F presents w/acute abdominal pain and lab eval is significant for a markedly increased serum amylase. Two days after admission, serum lipase becomes elevated as well. Which of the following is the most likely etiology for her serum enzyme elevation? Gall stones. (Other choices: Cystic fibrosis, Pancreas divisum, Solid pseudo-papillary neoplasm, Autoimmune pancreatitis) Test q: A 40M presents w/severe abdominal pain. Eval of the patient is significant for marked elevation of serum lipase and amylase. Of the following, which is the most likely etiology for the patient’s condition? Cholelithiasis. (Other choices: Familial pancreatitis syndrome – SPINK1 deficiency, Parasitic infection, Adenocarcinoma of the pancreatic head, Atherosclerosis) Test q: A 38F w/a long history of gallbladder disease has a sudden onset of severe mid-abdominal pain. On phys exam, she has marked abdominal tenderness, particularly in the upper abdomen, and bowel sounds are reduced. An abdominal radiograph shows no free air, but there is marked soft tissue edema. Abdominal CT-scan shows decreased attenuation w/fluid density along w/many small, bright foci of calcification involving the pancreas. She is given IV fluids and nasogastric suction and recovers gradually. Which of the following serum lab findings is most likely to be reported in this disease process? Increased amylase level. (Other choices: Hyperammonemia, Hypoglycemia, Increased ALT level, Hypokalemia) REPEATED x2

Chronic pancreatitis: • Middle aged male, alcoholic, or bile tract disease • Occasionally due to other causes o Tumor o Cystic fibrosis o Autoimmune (increased IgG4 expressing plasma cells in pancreas)  Histologically, see lots of plasma cells around the ducts. • 12% have pancreas divisum • Gross: hard, fibrotic (white, scar-like), may have stones or pseudocysts • Micro: fibrosis, loss of acini w/sparing of the islets and ducts  o Also chronic inflammatory cells

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1. Chronic pancreatitis secondary to cystic fibrosis (note fibrosis, loss of acinar cells, mucus in ducts). Histologically, can’t distinguish CF pancreatitis from other pancreatitis. History can help – more likely in a young patient. 2. Autoimmune pancreatitis (with abundant plasma cells). Test q: A 45F presents w/abdominal pain and jaundice. Lab eval is significant for elevation of serum amylase, lipase, and IgG4. Endoscopic ultrasound eval demonstrates a 4cm ill-defined mass in the head of the pancreas. A core needle biopsy is performed. The needle core biopsy shows cytologically bland ductal epithelium w/surrounding fibrosis, lymphocytes, and plasma cells. The most likely diagnosis is: Autoimmune pancreatitis. (Other choices: Pancreatic adenocarcinoma – ductal type, Acute pancreatitis, Intraductal papillary mucinous neoplasm, Multiple myeloma) REPEATED x2

Pancreatic Cancer • Precursors – pancreatic intraepithelial neoplasia/intraductal papillary mucinous neoplasm (IPMN) • At presentation small in head due to obstruction, larger in body/tail (may be 8-10cm) • May extend directly to the spleen, adrenal • Metastasis to peripancreatic LN, liver Pancreatic cancer in head of pancreas  Clinical Course • Weight loss, abdominal pain, nausea, vomiting, weakness, jaundice (90% of those arising in the head) • Trousseau’s syndrome (only 10%): migratory thrombophlebitis caused by platelet aggregating factors secreted by the tumor •