Other GI Tumors Flashcards
What kind of cells make up serosa?
mesothelial cells –> if none, it is called an adventitia
Smooth muscle tumors of GI tract
leiomyoma and leiomyosarcoma (rare in GI)
Most common mesenchymal tumor of esophagus?
leiomyoma –> lower 1/3 of esophagus, often presents with dysphagia
What is the term to describe multiple leiomyomas in the esophagus?
esophageal leiomyomatosis
How do leiomyomas appear on colonoscopy?
incidental small nodules
How common are leiomyomas in stomach and small intestine?
rare
GIST stands for…
gastrointestinal stromal tumor
What is the most common mesenchymal tumor of entire GI tract?
GIST –> most in stomach/small intestine vs leiomyoma in esophagus and colon
Immunohistochemistry findings in GIST
ckit/CD117 + and driven by KIT, PDGRFA/SDH mutations
What cells do GIST tumors derive from/differentiate to?
interstitial cells of Cajal
In which GI layers do GIST occur?
near the 2 plexi so around MM/submucosa/MP –> will appear submucosal vs epithelial
GIST morphologies
spindle cell (ice cream cone), epithelioid (plump, prominent nucleoli)
T/F a large portion of GISTs do not stain with Kit
F –> a very small minority: 5% do not stain
c-Kit negative GISTs are more likely to have what morphology and what mutations?
epithelioid morphology and PDGFRA mutation
What IHC might be used in c-kit negative cases?
dog1
Tx of GIST
surgical resection, imatinib (based on mutation), sunitibe malate for those with imatinib resistance
80% of GIST have a mutation in what gene?
KIT
5-7% of GIST have a mutation in what gene?
PDGFRA
What are wildtype GIST?
10-15% without a mutation in either KIT or PDGFRA
What kinds of people have SDH mutations that lead to GIST?
pediatric gastric GIST
T/F Imatinib response in GIST depends on the specific mutation you have.
T –> e.g. Exon 11 kit is best response and exon 18 PDGFRA is resistant
What is better? gastric or small intestine GIST
gastric GISTs do better
3 factors that determine GIST behavior
location, size, mitotic count
Benign or malignant? stomach gists
20% malignant
Benign or malignant? small intestine gists
50% malignant
Benign or malignant? esophagus/colon gists
malignant
2 important hereditary associations with GIST
NF1, Carney’s triad
What is Carney’s triad?
young females with gastric epithelioid GISTs, pulmonary chondroma/hamartomas, paraganglionomas
How can you tell the difference between a neuroendocrine cell and a paneth cell on histology?
neuroendocrine cells have granules facing away from lumen
2 types of neuroendocrine tumors
well differentiated/carcinoid and poorly differentiated
T/F Well-differentiated NETs are functional
F –> some can be functional and secrete hormone and others can be non functional
2 types of poorly differentiated NETs
small cell and large cell (more cytoplasm, less common)
Endoscopic view of NET
yellow tinged sessile nodules with intact surface +/- erosion
In which GI layer do NETs develop?
mucosal/submucosal junction
Cytology of NETs
salt n pepper nuclear chromatin
NET IHC (3) markers
synaptophysin, chromogranin, CD56
Are functional NETs of the luminal GI tract more or less aggressive than tumors of the pancreas or nonfunctional NETs?
more aggressive
What is carcinoid syndrome caused by?
increased serotonin produced by an NET
Carcinoid syndrome clinical findings
serotonin –> flushing of skin, diarrhea/cramps, right side heart disease via fibrosis of tricuspid, increased 5-hiaa urine execretion
Why does carcinoid syndrome usually imply metastatic disease?
when the primary tumor is in the GI tract, serotonin is inactivated in liver by first pass —> carcinoid presents once there are mets to the liver and serotonin can no longer be broken down
T/F gastrinomas arise from the duodenum
F –> 50% pancreas, 50% duodenum 1st/2nd parts
What syndrome is associated with gastrinomas?
MEN1 (25%), ZES (peptic ulcers, enlarge rugae, diarrhea)
T/F gastrinomas are usually indolent
F –> 70% metastasize aggressively –> also, no first pass metabolism since degraded in kidney –> therefore, can have a funcitonal tumor without a met
Dx of gastrinoma
increase in serum gastrin
Most common site for extranodal lymphomas
GI tract (stomach > small intestine/colon)
Predisposing factors for extranodal lymphomas
Hpylori, celiac disease, IBD, immunodeficiency
3 groups of low grade B cell lymphomas
marginal zone/MALT, follicular, mantle cell
2 groups of high grade B cell lymphomas
diffuse large B-cell, Burkitt
T cell lymphoma of GI tract
enteropathy type T-cell lymphoma
B cell migration path
bone marrow –> naive cells of the mantle zone –> germinal center –> paracortex or marginal zone or die
Most common lymphoma in stomach?
MALT
Most common lymphoma in small bowel?
follicular
Most common lymphoma in colon?
mantle zone
Most common association with MALT lymphoma?
Hpylori
How aggressive is MALT lymphoma?
indolent –> 5 year survival = 90 5, 75% respond to hpylori eradication via antibiotics
3 features of MALT lymphomas that do not respond to Hpylori eradication?
t(11:18) API2-MALT1, transformation to DLBCL, spread byeond stomach
- can try surgery, radiation, chemo
Most important MALT lymphoma translocation
t(11:18) API2-MALT1 aka the one that persists after Hpylori is treated
MALT lymphoma histology
intact germinal center, expanded marginal zone, lymphoepithelial lesion, monocytoid halo around cell
2 presentations of follicular lymphoma
mass (duodenum, favorable), 50% as lymphomatous polyposis (polyps)
Diff Dx of lymphomatous polyposis
reactive lymphoid hyperplasia (HIV/immunodeficiency), Mantle zone lymphoma of colon, follicular lymphoma (50% of them present like this, usually in small bowel)
Most common translocation in follicular lymphoma?
t(14:18) BCL2
Function of BCL2
prevents cells from undergoing apoptosis
How do you distinguish follicular lymphoma from follicular hyperplasia?
BCL2+ vs BCL2-
Can you dx lymphoma based on BCL2?
no –> it is normally expressed in non-germinal center cells…but if it’s in germinal center, it’s neoplastic
How does mantle cell lymphoma present?
colonic lymphomatous polyposis
Mantle cell lymphoma prognosis
terrible –> it’s very aggressive
Histologic appearance of mantle cell lymphoma
colon with vaguely nodular lymphoid aggregate with monomorphic cells/round, slightly celfted
Main translocation in mantle cell lymphoma?
t(11,14) cyclin d1/BCL1-Ig
What is cyclin d1?
promoter of cell cycle progression overexpressed in mantle cell lymphoma
Dx of mantle cell lymphoma?
IHC of NUCLEAR cyclin D1
Most common lymphoma of the whole GI tract?
DLBCL
DLBCL prognosis
bad –> very aggressive
DLBCL morphology
large lymphocytes with a high proliferation rate
Burkitt lymphoma derives what cells?
germinal center B cells
Morphology of Burkitt
starry sky due to tingible body macrophages in a sea of medium lymphocytes
Burkitt prognosis
high grade/aggressive
Most common translocation in Burkitt?
t(8:14) c-myc-IgH (80% of cases)
What kind of Burkitt presents in abdomen?
non-endemic sporadic variant –> adult abdomens (5% EBV+)
What lymphoma has a high association with celiac disease?
enteropathy type T cell –> jejunum and ileum
What condition often precedes enteropathy type t cell lymphoma?
refractory sprue
Prognosis of enteropathy type t cell lymphoma?
aggressive –> median survival of 3 months
Histologic presentation of enteropathy type t cell lymphoma
variable sized lymphocytes (some are intraepithelial) with mixed inflammatory background
Dx of enteropathy type t cell lymphoma
cellular atypia, aberrant tcell antigen expression (loss of CD8), clonality
