50. Colonic polyps

Question 1

colonic polyps ?

Answer 1

frowth of tissue within the coln –> neoplastic or non- neoplastic

Question 2

colonic polyps - gross appearance

Answer 2

flat, sessile , or pedunculated ( on a stalk ) on the basis of protrusion into colonic lumen

Question 3

histological types ( neoplastic or not ?)

Answer 3

1. hyperplastic - non neoplastic
2. hamartomatous - non neoplastic
3. adenomatous - neoplastic
4. serrated - premalignant

Question 4

cyperplastic - apperance and location

Answer 4

non- neoplastic generally smaller and majority located in RECTOSIGMOID area

Question 5

Colonic polyps - hamartomatous - apperance

Answer 5

non- neoplastic . growth of normal colonic tissue with distorted architecture

Question 6

hamartomatous - associated with …. malignant ?

Answer 6

associated with Peutz-Jegjers syndrome and juvenile polyposis
- solitary lesions do not have risk of malignant transformation

Question 7

adenomatous - mechanism / presentation

Answer 7

chromosomal instability patheay with mutations in APC and KRAS. presentation : usually asymptomatic, may present with occult bleeding

Question 8

adenomaatous - types and malignancy

Answer 8

tubular –> less malignant potential
villous –> more malignant potential
tubulovirous –> intermediate malignant potential

Question 9

serrated - mechanism / biopsy

Answer 9

premalignant , via CpG hypermethylation phenotype pathway with microsatellite instability
biopsy: saw tooth pattern of crypts

Question 10

serrated - malignancy

Answer 10

up to 20% of cases of sporadic colorectal cancer

Question 11

microsatellite instability is the condition of

Answer 11

genetic hypermutability that results from impaired DNA mismatch repair ( MMR)

Question 12

• A man has a biopsy of a colonic polyp. The more ____ (villous/sessile/tubular/hyperplastic) it is, the more likely that it is malignant.

Answer 12

Villous

Question 13

• Your 50-year-old patient has a history of hyperplastic polyps. On colonoscopy, where do you most expect to find new hyperplastic polyps?

Answer 13

In the rectosigmoid area

Question 14

• A child with rectal discomfort has a single rectal juvenile polyp on colonoscopy. He is otherwise well. Should be polyp be urgently removed?

Answer 14

No; there is no malignant potential if it is truly the only juvenile polyp

Question 15

• The malignancy risk of adenomatous polyps is not associated with ____ (degree of dysplasia/villous histology/size/symptoms).

Answer 15

Symptoms

Question 16

• What type of polyp is considered a precursor for colorectal cancer?

Answer 16

Adenomatous polyps

Question 17

• List these three adenomatous polyp subtypes in order of their potential for malignant transformation, from lowest to highest.

Answer 17

Tubular adenomas, tubulovillous adenoma, villous adenomas

Question 18

• What two conditions are associated with the formation of hamartomatous polyps?

Answer 18

Peutz-Jeghers syndrome and juvenile polyposis

Question 19

• APC and KRAS, which are commonly mutated via the

Answer 19

chromosomal instability pathway in neoplastic polyps

Question 20

• A patient has a colonoscopy. Polyps are biopsied, and “saw tooth” crypts are seen. Is there a risk of progression to colorectal cancer?

Answer 20

Yes, as the biopsy description is consistent with serrated polyps, which are premalignant (~20% of sporadic colorectal cancer cases)

Question 21

• What genetic mutations are associated with serrated polyps?

Answer 21

The CpG hypermethylation phenotype pathway with microsatellite instability, and mutations in BRAF