3/22 NET - Wondisford

Question 1

two main categories of NETS

Answer 1

1. GI-NETs (aka carcinoids)
2. pNETs

*originally thought to be of NC origin but are not - actually derived from local multipotential cells in gut crypts

Question 2

morphology

Answer 2

• small, slow growing cells in sheets
• silver stainers
• • for NE markers
    
    • neuron-specific enolase
    • chromogranin A
    • synaptophysin
• neurosec granules containing predominant peptide

Question 3

Answer 3

Question 4

insulinoma

Answer 4

most common pNET

age 40-50 (more in F)

clinical: hypoglycemia with fasting

• sweating, tremors, tachycardia, confusion, weakness
• measured inapprop level of insulin and C-peptide with hypoglycemia (glucose < 40)

Whipple’s triad:

1. sx related to hypoglycemia
2. low pl glucose at time of sx
3. sx relief when glucose raised to normal

tx: surgery or diazoxide/somatostatin (bc either blocks insulin release)

Question 5

ZE syndrome

Answer 5

Zollinger Ellison

severe and recurrent peptic ulcer disease sx

mean age: 30-50yo

assoc w MEN1

• found in gastrinoma triangle: pancreas, duodenum, stomach

dx: high gastrin and low gastric pH

tx: surgery, chronic PPI

• side effects: incr fracture, B12 deficiency

Question 6

VIPoma

Answer 6

pancreatic tumor (usually) releasing excessive VIP

sx:

• large volume secretory diarrhea
• hypokalemia
• hypochlorhydria

aka Verner-Morrison syndrome, pancreatic cholera, WDHA syndrome (watery diarrhea, hypokal, achlorhydria)

Question 7

glucagonoma

Answer 7

excessive glucagon secretion

large lesions in pancreas (usually tail)

glucagon > 1000

clinical manifestations:

• migratory necrolytic erythema
• glucose intolerance
• hypoaminoacidemia (protein breakdown induced by high glucagon)

Question 8

somatostatinoma

Answer 8

tumor in pancreas/sm int releasing excess SST

sx:

• triad: gallstones, diabetes, diarrhea
• blockade of exocrine pancreas secretion → steatorrhea, diarrhea

duodenal SSToma? → assoc w von Recklinghausen’s disease (NF1)

Question 9

tx for VIPoma, glucagonoma, somatostatinoma

Answer 9

• fluid and electrolyte support
• surgical removal if possible
• octreotide

Question 10

carcinoids and carcinoid syndrome

Answer 10

• relatively rare tumors, usually in ileum and lung
• local effects (bleeding, pain, obst) until hepatic metastases or access to circulation
  
  • 5HT in systemic circulation →→→
    
    • stim of intestinal secretion
    • inhibition of absorption
    • incr int motility
    • stim fibrogenesis

sx: secretory diarrhea, facial flushing, abd pain, TV/PV fibrosis, bronchospasm
* can deplete Trp → niacin deficiency and pellagra
dx: elevated 5HIAA, chromagranin A, + octreotide scan
tx: surgery, octreotide