Tumors of the Small and Large Bowel Flashcards
What are risk factors for SI adenocarcinoma?
Crohn’s disease
adenomas
celiac disease
What is GIST?
gastrointestinal stromal tumor
most common non-epithelial/soft tissue tumor in GI tract
derived from pacemaker cells (interstitial cells of cajal)
What is useful for treatmetn of GIST?
imatinib
What are the markers of GIST?
CD117 (c-kit)
DOG1
CD34
Describe carcinoid syndrome
vasomotor disturbances, intestinal hypermotility, wheezing, hepatomegaly, cardiac involvement
(increased serotonin)
Define non-neoplastic polyp
result of abnormal mucosal maturation, inflammation, distorted architecture
no malignant potential
Describe neoplastic polyp
arise as a result of proliferatio nnad dysplasia (adenomas)
precursor of carcinoma
What are the types of non-neoplastic polyps?
hamartomatous
inflammatory
lymphoid
What is a hamartoma?
benign w/no malig pot
composed of mature, histologically normal elements from that site growing in a disorganized manner
What are different types of hamatomatous polyps?
juvenile polyps
peutz jeghers polyps
cowden syndrome
cronkhite-canada
Features of juvenile polyps?
kids <5 80% in rectum pedunculated expanded lamina propria hamartomatous non-neoplastic
What genes are associated with juvenile polyposis syndrome? other features?
SMAD4, BMPR1A
increased risk of adenomas
10-50% risk of colon cancer
multiple juvenile polyps
What is peutz jeghers syndrome?
AD STK11
mutliple GI polyps
hyperigmentation of the mouth and fingers
increased risk of intussusception
increased risk of cancer of the pancreas, breast, lung, ovary, uterus
large and pedunculated, lots of goblet cells
What is cowden syndrome?
AD hamartomatous GI polyps facial trichilemmomas, oral papillomas, acral keratoses assoc risk of thyroid and breast cancer polyps themselves no malig pot
What is cronkhite-canada?
non hereditary
GI hamartomatous polyps
ectodermal abnormalities (nail atrophy, alopecia)
What are inflammatory polyps?
pseudopolyps-regenerating mucosa adjacent to ulceration (seen in severe IBD)
What are lymphoid polyps?
mucosal bumps caused by intramucosal lymphoid follicles-normal
What are serrated polyps?
smooth protrusions of mucosa usally at the top of mucosal fold
serrated lamina nad increased numbers of goblet cells
hyperpastic or sessile
Which type of serrated polyp has malignant potential?
sessile serrated
BRAF V600E mutations
What are adenomatous polyps? (adenomas)
Arise as a result of epithelial proliferative dysplasia
precursor lesions for adenocarcinoma
-tubular, villous, and tubulovillous adenoma
fourfold greater risk of developing adenomas among 1st deree relatives of pts w/ & risk of developing carcinoma
Where are most tubular adenomas found?
colon
What are villous adenomas?
villous projection
often large, sessile
older ppl in rectosigmoid
cancer invasion directly into colon wall
What is the only adequate treatment for an adenoma?
complete resection
What is the most common colorectal cancer?
adenocarcinoma
-usually in rectosigmoid
What are risk factors for colorectal cancer?
diet
obesity/inactivity
geography?
What is right sided colon cancer usually like?
non obstructive
fatique, weakness, iron deficiency anemia
polypoid eophytic lesions
What is left sided colon cancer usually like?
may be obstructive
occult bleeding, changes in bowel habit, abd discomfort
annular napkin ring constrictions
tend to be more infiltrative
What gene(s) are often inactived in adenoma carcinoma pathway?
inactivated APC
if not inactivated APC B-catenin mutations
(leads to increased WNT signaling, decreased cell adhesion and increased cellular proliferation)
loss of p53 late
What is the depth of invasion for TIS-T4
TIS carcinoma in situ T1 submucosa T2 muscularis propria T3 serosa T4 other organs/structures
What is the most important prognostic indicator of colorectal carcinoma?
Stage=T + M + N
Where does colon cancer like to spread?
lymph nodes, liver, lungs, bones
What is the major negative predictor of efficacy in EGFR moAB therapy?
KRAS mutation
BRAF mutation correlates with poor prognosis and lack of response
Describe FAP
AD mutation of APC gene
>100 colonic adenomas
colon adenocarcinoma 100% of the time
prophylactic colectomy
What is gardner’s syndrome?
FAP variant
adenomatous polyposis with osteomas, epidermoid cysts, desmoid tumros
What is turcot syndrome?
FAP variant
adenomatous polyposis with medulloblastoma
What is MAP?
aka MYH associated polyposis hereditary colorectal cancer syndrome that has phenotypic overlap w/FAP 20-100 adenomatous polyps usually AR due to mutations in MYH gene presents older than FAP
What does MYH protein do?
DNA repair protein-base excision repair
repairs oxidation induced DNA damage by removing A mis-paired with G
What is lynch syndrome?
increased risk of colorectal & endometrial cancer in females (also SI, ureter, renal pelvis)
adenomas earlier than normal pop but in low nubers
microsatellite instability pathway, DNA mismatch repair genes busted
What is Muir Torre syndrome?
a lynch syndrome variant
associated wtih multiple sebaceaous adenomas, sebaceous carcinomas, and keratoacanthomas
What does microsatellite instability lead to?
accumulation of mutations in the genome
What do microsatellites serve as sensitve markers of?
mistmatch repair function
-typically microsatellites are shorter in tumor tissue
Is braf mutation seen in lynch syndrome?
No! never
What are the 2 main types of anal canal carcinoma?
basaloid differentiation
squamous cell
What is the most common tumor of the appendx?
carcinoid
What is a mucinous cystadenoma/cystadenocarcinoma?
a mucous secreting epithelial tumor
creates mucoceles
What is pseudomyxoma peritonei?
“jelly belly”
mucin from mucinous cystadenoma/cystadenocarcinoma leaks into the peritoneal cavity and encases organs
