Neuroendocrine tumors Flashcards
most common location of carcinoid tumors
GI tract 55%
Lungs 35%
symptoms of carcinoid syndrome
flushing diarrhea hypotension pruritis telangiectasias on the face (prolonged vasodilitation)
difference in pulmonary vs gastric NET flushing
gastric - short, patchy, intensely pruritic
pulmonary - hours - days, more severe
biochemical mediators of carcinoid syndrome
serotonin (diarrhea) histamine (flushing, wheezing) kallikrein bradykinin tachykinin prostaglandin
carcinoid syndrome does NOT usually occur with midgut NETs except in which case
extensive liver mets
what vitamin deficiency is associated with carcinoid syndrome
pellagra (vit B3 def) - large amounts of tryptophan are diverted from niacin synthesis to produce serotonin
carcinoid tumors can also cause which endocrine syndromes
cushings (ACTH or CRH producing)
acromegaly (GHRH)
5-HIAA is a metabolite of what
serotonin
metabolism of tryptohpan
tryptophan - serotonin - 5-HIAA
foods/meds that can cause false + 5-HIAA levels
tryptophan, serotonin
diagnosis of carcinoid syndrome
elevated 5-HIAA in urine
which test is NOT recommended in diagnosis of carcinoid syndrome
chromogranin A (nonspecific)
which carcinoids can cause carcinoid syndrome but have normal 5-HIAA levels
foregut carcinoids (lack enzyme to convert tryptophan to serotonin
best imaging to localize NETs
CT
MRI (better to eval for hepatic mets)
Octreoscan
DOTOATATE
what % of carcinoid tumors are metastatic at the time of diagnosis
90%
treatment of carcinoid syndrome
somatostatin analogues telotristat (inhibits rate limiting step in serotonin synthesis) chemo (respond poorly) radioreceptor therapy hepatic resection/embolization
symptoms of carcinoid crisis
flushing, hypotension, wheezing/bronchospasm
pretreatment of pts with carcinoid syndrome prior to going to the OR
octerotide 300-500mcg subQ 30-60 min prior to procedure
which patients should received prophylaxis to prevent carcinoid crisis
symptomatic carcinoid syndrome
metastatic carcinoid - measure 5-HIAA levels and treat if elevated
treatment of carcinoid crisis
iv octreotide glucocorticoids methotrimeprazine methoxamine phentolamine ondansetron glucagon NO ADRENERGIC OR SYMPATHOMIMETIC AGENTS -- can make the condition worse
% of PNETs that are nonfunctional
50-70%
what % of insulinomas are benign?
80-90%
what % of PNETs (besides insulinoma) are malignant?
50-80%
what % of MEN1 pts have PNETs?
80-100%
clinical manifestations of gastrinomas
severe peptic ulcer disease
secretory diarrhea
also known as Zollinger-Ellison syndrome
typical locations of gastrinomas
70% duodenum
25% pancreatic islets
diagnosis of gastrinoma
serum gastrin level > 1000
gastric pH < 4.0
secretin stimulation test with gastrin rise > 200 pg/mL
off PPI for 1 week
functional test for diagnosis of gastrinoma
secretin stim test
gastrin rise of > 200 pg/mL 15 minutes after IV secretin administration
imaging modalities for gastrinoma localization
CT/MRI EUS DOTATATE Octreoscan transportal venous sampling selective arterial secretin stimulation
treatment of gastrinomas (benign)
surgery
high dose ppi
somatostatin analogues (octreotide, lanreotide)
H2 blockers
refractory - vagotomy or subtotal gastrectomy
treatment of malignant gastrinomas
surgery
liver mets - surgery, embolization, liver xplant, radioreceptor therapy, chemo
presentation of glucagonomas
DM wt loss anemia necrolytic migratory erythema VTE
diagnosis of glucagonoma
glucagon levels > 500 pg/mL (but not always this high)
localization of glucagonomas
same as gastrinomas: CT/MRI EUS DOTATATE Octreoscan transportal venous sampling selective arterial secretin stimulation
treatment of glucagonomas
surgery for localized disease somatostatin analogues liver-directed therapies chemo radioreceptor therapy tx overall similar to gastrinomas**
tx for skin rash associated with glucagonomas
zinc, amino acid infusions
characteristics of somatostatinomas
DM weight loss steatorrhea hypochloridia cholelithiasis
diagnosis of somatostatinoma
elevated serum somatostatin level
treatment of somatostatinomas
surgery
characteristics of VIPomas
watery diarrhea
kypokalemia
achlorhydria
diagnosis of VIPoma
elevated serum VIP level
treatment of VIPoma
surgery