Neoplastic GI

Question 1

Tumors of the Small Bowel

Answer 1

Longest segment of GIT but only 3-6% of all GIT tumors
Benign tumors are slightly more common than malignant ones
Small intestine and appendix – most common site in GI tract,

Question 2

Carcinoid syndrome

Answer 2

wheezing, diarrhea, flushing

Question 3

Colorectal polyps

Answer 3

Polyp is any lesion projecting into the lumen, non-specific gross descriptive term
Most common non-neoplastic polyp = hyperplastic
Most common neoplastic polyp = adenoma

Question 4

Juvenile polyp

Answer 4

Common in children < 5 years of age but also seen in adults, rectum is most common site,

Sporadic single polyps 🡪 NO MALIGNANT POTENTIAL
Juvenile polyposis syndrome 🡪 increased risk of malignancy

Question 5

Peutz Jegher’s polyp (Hamartomatous polyp)

Answer 5

PJ syndrome – autosomal dominant, multiple polyps in whole GIT, melanotic pigmentation in mucucutaneous areas/lips/perioral areas/face/genitalia/palms

Question 6

Adenomas

Answer 6

All arise as a result of epithelial proliferative dysplasia
3 types – tubular, villous, tubulovillous
Are precursor lesions of carcinoma
Risk increases with polyp size (most important criteria), histologic architecture, severity of dysplasia
90% colon,

Question 7

Familial polyposis syndromes

Answer 7

FAP – genetic defect in APC gene (5q21)
Usually tubular type, sometimes in SI and stomach, typically 500-2500 mucosal adenomas (minimum number for diagnosis is 100), carcinoma occurs in young individuals, prophylactic colectomy is done

Question 8

Gardner syndrome

Answer 8

tubular adenomas with multiple osteomas, desmoid tumors, and epidermal cysts

Question 9

Turcot syndrome

Answer 9

adenomas and CNS gliomas

Question 10

Genetic etiology of FAP

Answer 10

ne allele of APC gene inherited in a mutated form, mutation is present in every cell of colon, polyp growth begins when 2nd allele is somatically mutated thus causing loss of gene function

Question 11

Colorectal carcinoma

Answer 11

in elderly individuals
Occurs in young individuals in setting of ulcerative colitis and polyposis syndromes
Risk factors – obesity, physical inactivity, diet low in indigestible fiber and rich in animal fat, antioxidants protective
Right sided (more silent) – fatigue, weakness, iron deficiency anemia (bulky and bleed easily)
Left sided – altered bowel habits
Tumor marker – CEA

Question 12

Chromosomal instability pathway

Answer 12

(85-90% cases) – arise from adenoma-carcinoma sequence, APC gene mutations, FAP/Gardner/Turcot syndromes

Question 13

MSI pathway

Answer 13

(10-15% cases) – may arise from adenomas or other lesions (SSA or HP), defect in DNA mismatch repair genes

Question 14

Hereditary non-polyposis colorectal cancer (HNPCC)

Answer 14

lso known as Warthin-Lynch syndrome
Defective DNA repair genes (AD)-MLH1 gene
Fewer number of polyps as compared to FAP
Tumors – may be multiple, more common on right side (