Neoplasia of intestines Flashcards
What might explain the lower incidence of malignancy in the small intestine?
rapid transit time of enteric contents through the small bowel
lower concentrations of bacteria
lots of immune surveillance with intramural lymphoid tissue.
____ tumors are a subset of neuroendocrine tumors that appear in the GI tract
carcinoid
What might explain the increasing incidence of carcinoid tumors?
detection bias- modern CT imaging
Caucasian patients tend to have more _____ carcinoids and Africans have more ______ carcinoids
bronchial
rectal
What genetic syndromes are associated with carcinoid?
Multiple endocrine neoplasia- MEN1 gene mutations, associated with parathyroid and pituitary tumors
von Hippel-Lindau- autosomal dominant, associated with renal cell carcinoma, cerebellar hemangioblastoma, pheochromocytoma
_________staining is performed to identify and classify carcinoid tumors
immunohistochemical
Carcinoid arises from _____ cells in the gut
Kulchitsky
What are the classic findings of carcinoid syndrome?
flushing
diarrhea
bronchospasm
right heart failure
What causes flushing in carcinoid syndrome?
catecholamine mediated
NOT caused by serotonin
Vasodilation can be due to substances released by the tumor cells, including bradykinin, substance P, tachykinins, and prostaglandins
How is flushing in carcinoid syndrome treated?
antihistamines
What causes diarrhea in carcinoid syndrome?
increased gut motility mediated by serotonin
Describe the heart disease seen in carcinoid syndrome
late complication
Fibrotic deformation of the tricuspid and pulmonary valves usually leads to pulmonary stenosis and tricuspid insufficiency
In carcinoid, treatment with _____ appears to slow progression of heart disease
octreotide
How is carcinoid tumor diagnosed?
24 hour 5-HIAA urine collection
chromogranin A
CT and MRI imaging including octreotide scanning
Other than carcinoid, what are possible causes of elevated chromogranin A?
PPIs, H2 blockers
hepatic or renal insufficiency
Describe histopathology of neuroendocrine tumors
heavily vascularized
salt and pepper chromatin
trabeculations within stroma
immunochemistry for chromogranin or synaptophysin
List biochemical manifestations of carcinoid
Glucose intolerance
Low-grade anemia
Electrolyte imbalances indicative of chronic diarrhea
How is grade of carcinoid tumor quantified?
Ki-67 proliferation index
mitotic count
______ is the gold standard in treatment of carcinoid tumors
surgical resection
extend depends on risk of recurrence. ex tumor less than 1 cm- simple appendectomy; tumor >2 cm- appendectomy with R hemicolectomy
_______ can offer symptomatic relief when curative surgery is not possible
surgical debulking
________ is use for symptomatic tumors as an alternate to surgery when cure is not possible
ablation
______ was developed for symptomatic relief but actually slows progression/ improves progression free survival
octreotide
______ and ______ have FDA approval for treatment of pancreatic NET
Sunitinib and everolimus, relatively ineffective in carcinoid subset
Low grade carcinoid tumors are often chemotherapy _____
resistant
Intravenous or subcutaneous _____ inhibits carcinoid flush, but is not practical for therapy because it has a half-life of less than 2 minutes
somatostatin
MALTomas are ______ lymphomas associated with H pylori infection
B cell
What is appropriate treatment for localized MALTomas?
treatment to eradicate H. pylori- can lead to complete and sustained response
What is appropriate treatment to eradicate H pylori?
PPI plus amoxicillin plus clarithromycin (or metronidazole)
In MALToma, what are predictors of worse outcome?
lymph node involvement
high grade features
_______ is a rare B cell non-Hodgkin lymphoma that can occur in the GI tract
Mantle cell lymphoma
Mantle cell lymphoma in the gut is sometimes called _______ because it presents as a field of polyps with a lymphoid rich infiltrate
lymphatomatous polyposis
Mantle cell lymphoma is ______ to most current chemotherapy regimens
refractory
_______ can have GI involvement but is rare
follicular lymphoma
GIST arises from what cell type?
Interstitial cells of Cajal
pacemaker cells of the gut
How does GIST present?
vague abdominal discomfort, nausea, early satiety, and very rarely cause obstructive symptoms
What is the most common site of GIST?
stomach> small intestine> rectal
Even low grade GISTs have some ______ potential
malignant
_____ is pathognomonic for GIST
c-kit mutation
Treatment of GIST involves surgical resection and adjuvant therapy with ____
imatinib
originally thought 1 year, now may be lifetime
Imatinib was designed to target bcr-abl fusion protein in CML but has off-target effects on ______
tumors overexpressing c-kit
List familial syndromes possibly associated with GIST
NF1 and Carney triad
