8. Tumours of the Lower GIT

Question 1

Name the benign tumours of the small intestine

Answer 1

Adenoma (25%)
Mesenchymal tumours:
Leiomyoma
Lipoma
Angioma

Question 2

Name the malignant tumours of the small intestine

Answer 2

Adenocarcinoma and carcinoid

Lymphoma and sarcoma

Question 3

Name the benign tumours of the colon and rectum

Answer 3

Non neoplastic polyps

Neoplastic - adenoma

Question 4

Name the malignant tumours of the colon and rectum

Answer 4

Adenocarcinoma (98%)
Carcinoid
Anal zone carcinoma
Lymphoma
Leiomyosarcomas

Question 5

Describe adenoma of the small intestine

Answer 5

30-60 yr old with occult blood loss
Affects ampulla of vater
Malignant potential
Occur in duodenum
40-70 yr old
Napkin ring encircling pattern
Polypoid exophytic masses
Intestinal obstruction
Cramping, nausea, vomiting, weight loss
May cause obstructive jaundice

Question 6

Describe non-neoplastic polyps of the colon and rectum

Answer 6

Hyperplastic (90%):
Nipple like
1/2 found in rectosigmoid colon
No maligant potential

Hamartomatous:
Juvenile polyps: 
Malformations of the mucosal epithelium and lamina propria
80% in rectum
No malignant potential

Peutz-Jeghers polyps:
Autosomal dominant syndrome
Stomach 25%
Colon 30%

Question 7

Describe the neoplastic polyps of the colon and rectum

Answer 7

Tubular adenomas 75%
Villous adenomas 1-10%
Tubulovillous adenoma 5-15%

Question 8

Describe the incidence of colorectal carcinoma

Answer 8

98% of large intestine cancers are Adenocarcinomas

Question 9

What dietary factors can lead to colorectal carcinoma

Answer 9

Excess dietary caloric intake
Low content of vegetable fibre
High content of refined red meat
Decreased intake of protective micronutrients

Question 10

Describe the morphology of colorectal cancers

Answer 10

Rectosigmoid colon 55%
Caecum/ascending colon 22%
Transverse colon 11%
Descending colon 6%
Other sites 6%

Question 11

Describe tumors in the proximal colon

Answer 11

Polypoid, exophytic masses
Obstruction is uncommon
Penetrate the bowel wall as subserosal and serosal white, firm masses

Question 12

Describe tumours in the distal colon

Answer 12

Annular, encircling lesions - napking ring constrictions
Margins are classically heaped up, beaded and firm and the mid-region is ulcerated
Penetrate the bowel wall as subserosal and serosal white firm masses

Question 13

Describe the clinical features of colorectal cancers

Answer 13

Caecum and right colonic:
fatigue, weakness, iron defiency anaemia
Left sided:
occult bleeding, changes in bowel habit, crampy LLQ

Question 14

Describe Dukes staging

Answer 14

A: confined to submucosa or muscle layer
B: spread through the muscle layer but does not yet involve lymph nodes
C: involving lymph nodes

Question 15

Describe carcinoid tumours

Answer 15

Derived from endocrine cells

No reliable histological difference between seemlingly benign and obiuously malignant carcinoid tumours