Other GI Tumors Flashcards
(53 cards)
What are the 3 categories of “other” (non-epithelial) tumors we’re talking about in the GI?
Mesenchymal -e.g. smooth muscle.
Neuroendocrine
Hematologic (e.g. lymphoma)
Are leiomyosarcomas common in the GI tract?
Very rare.
Where are leiomyomas most commonly found in the GI tract? Where are they uncommon?
Most common: Esophagus, also colon.
Uncommon in the stomach and small intestine.
Immunohistochemical stains for leiomyoma? (2 things)
Smooth muscle actin (SMA)
Desmin
What’s the most common mesenchymal tumor of the GI tract?
GIST - gastrointestinal stromal tumor
From what cell do GISTs probably arise? Where are these cells?
Interstitial cells of Cajal (ICCs) - pacemaker cells.
These cells are associated both this submucous plexus and myenteric plexus.
For what stain are most GISTs positive?
What’s different about the ones that don’t stain for it?
c-kit - about 95%
The rest are more likely to be epithelioid in morphology, and be driven by PDGFRA mutations.
What mutations are thought to drive GISTs?
KIT or PDGRFA
- both are gain of function mutations
Histological buzzwords for GIST?
Spindle cell, “ice cream cones.”
Or epithelioid.
What’s a new stain (other than c-kit) for GISTs?
DOG1
Treatments for GIST?
Surgery.
Tyrosine kinase inhibitors (esp Imatinib - Gleevec)
What is GIST response to imatinib based upon?
Type of mutation in the the tumor.
Best with exon 11/Kit, worst with exon 9.
Where are GISTs most common in the GI tract?
Most common in the stomach, then small intestine.
Rare in colon and esophagus.
(the opposite distribution from leiomyomas)
3 variables in GIST prognosis?
Location
Size
Mitotic count
2 hereditary associations with GIST?
NF1
Carney’s triad
What’s Carney’s triad?
Young females with …
Gastric epithelioid GISTs
Pulmonary chondroma (hamartomas)
Paragangliomas
What does the “neuro” in neuroendocrine (NE) cells refer to?
Production of peptides and amines stored in neurosecretory granules.
How can you distinguish NE cells from Paneth cells?
NE granules point basolaterally.
Paneth granules point toward the lumen.
3 categories of NE tumors (NETs)?
Which is most common in the GI tract?
Well-differentiated NE tumor - most common in GI tract.
Poorly-differentiated NE carcinoma, small cell type.
Poorly-differentiated NE carcinoma, large cell type.
(the latter 2 are very aggressive, but less common)
Why do NE tumors often have intact epithelium over them?
They arise from the epithelial - submucosal junction and push up the epithelium above them.
Buzzword for the histological appearance of NET nuclei?
Salt and pepper (or salt-n-pepa) nuclei.
3 NE markers you should know about?
Synaptophysin
Chromogranin
CD56
What does it mean for an NET to be functional? How does this relate to aggressiveness?
Functional = producing hormones.
In GI tract, functional usually means more aggressive.
Which cells in the GI tract make 5-HT, and what does it do?
Enterochromaffin cells (ECs) 5-HT increases GI motility and blood flow.
