50. Colonic polyps Flashcards
colonic polyps ?
frowth of tissue within the coln –> neoplastic or non- neoplastic
colonic polyps - gross appearance
flat, sessile , or pedunculated ( on a stalk ) on the basis of protrusion into colonic lumen
histological types ( neoplastic or not ?)
- hyperplastic - non neoplastic
- hamartomatous - non neoplastic
- adenomatous - neoplastic
- serrated - premalignant
cyperplastic - apperance and location
non- neoplastic generally smaller and majority located in RECTOSIGMOID area
Colonic polyps - hamartomatous - apperance
non- neoplastic . growth of normal colonic tissue with distorted architecture
hamartomatous - associated with …. malignant ?
associated with Peutz-Jegjers syndrome and juvenile polyposis
- solitary lesions do not have risk of malignant transformation
adenomatous - mechanism / presentation
chromosomal instability patheay with mutations in APC and KRAS. presentation : usually asymptomatic, may present with occult bleeding
adenomaatous - types and malignancy
tubular –> less malignant potential
villous –> more malignant potential
tubulovirous –> intermediate malignant potential
serrated - mechanism / biopsy
premalignant , via CpG hypermethylation phenotype pathway with microsatellite instability
biopsy: saw tooth pattern of crypts
serrated - malignancy
up to 20% of cases of sporadic colorectal cancer
microsatellite instability is the condition of
genetic hypermutability that results from impaired DNA mismatch repair ( MMR)
• A man has a biopsy of a colonic polyp. The more ____ (villous/sessile/tubular/hyperplastic) it is, the more likely that it is malignant.
Villous
• Your 50-year-old patient has a history of hyperplastic polyps. On colonoscopy, where do you most expect to find new hyperplastic polyps?
In the rectosigmoid area
• A child with rectal discomfort has a single rectal juvenile polyp on colonoscopy. He is otherwise well. Should be polyp be urgently removed?
No; there is no malignant potential if it is truly the only juvenile polyp
• The malignancy risk of adenomatous polyps is not associated with ____ (degree of dysplasia/villous histology/size/symptoms).
Symptoms
• What type of polyp is considered a precursor for colorectal cancer?
Adenomatous polyps
• List these three adenomatous polyp subtypes in order of their potential for malignant transformation, from lowest to highest.
Tubular adenomas, tubulovillous adenoma, villous adenomas
• What two conditions are associated with the formation of hamartomatous polyps?
Peutz-Jeghers syndrome and juvenile polyposis
• APC and KRAS, which are commonly mutated via the
chromosomal instability pathway in neoplastic polyps
• A patient has a colonoscopy. Polyps are biopsied, and “saw tooth” crypts are seen. Is there a risk of progression to colorectal cancer?
Yes, as the biopsy description is consistent with serrated polyps, which are premalignant (~20% of sporadic colorectal cancer cases)
• What genetic mutations are associated with serrated polyps?
The CpG hypermethylation phenotype pathway with microsatellite instability, and mutations in BRAF
