Lower GI Pathology

Question 1

State the management of pseudomembranous colitis

Answer 1

Metronidazole or oral vancomycin

Question 2

What is diverticular disease?

Answer 2

Outpouchings at weak points in the bowel wall due to high intraluminal pressure

Question 3

What % of diverticular disease occurs in the left colon?

Answer 3

90%

Question 4

State at least 3 complications of diverticular disease

Answer 4

Diverticulitis, gross perforation, fistulae, fibrosis and obstruction

Question 5

Describe the symptoms of carcinoid syndrome

Answer 5

Bronchoconstriction, flushing, diarrhoea

Question 6

What is carcinoid syndrome?

Answer 6

A diverse group of serotonin-producing tumours of enterochromaffin cell origin

Question 7

State the four most common locations of carcinoid syndrome tumours

Answer 7

Bowel, lung, ovaries, testes

Question 8

Describe the symptoms of a carcinoid crisis

Answer 8

Life-threatening vasodilation, hypotension, tachycardia, bronchoconstriction, hyperglycaemia

Question 9

How is carcinoid syndrome diagnosed?

Answer 9

24h urine 5-HIAA (main metabolite of serotonin)

Question 10

How is carcinoid syndrome managed?

Answer 10

Oral octreotide (somatostatin analogue)

Question 11

What % of over 50s in the UK have a colonic adenoma?

Answer 11

50%

Question 12

What are colonic adenomas?

Answer 12

Benign dysplastic lesions of the colon. Precursors to most adenocarcinomas, but most remain benign

Question 13

What are the criteria for regular adenoma surveillance?

Answer 13

> 3.4cm size, >45% malignant change

Question 14

State the three types of adenoma

Answer 14

Tubular, villous, tubulovillous

Question 15

What is the main consequence of villous adenoma?

Answer 15

Hypoproteinaemic hypokalaemia

Question 16

Describe the classical chromosomal instability sequence of adenoma to carcinoma progression

Answer 16

Normal colon undergoes a mutation in one copy of the APC gene, producing at-risk mucosa. At-risk mucosa undergoes a mutation in a second copy of the APC gene, producing an adenoma. The adenoma undergoes further mutations in k-ras, LOF, and p53, producing carcinoma.

Question 17

How does familial adenomatous polyposis increase the risk of adenocarcinoma?

Answer 17

One copy of the APC gene is already mutated

Question 18

What is the inheritance pattern of juvenile polyposis?

Answer 18

Autosomal dominant

Question 19

What are juvenile polyps?

Answer 19

Hamartomatous polyps: Focal malformations of the mucosa and lamina propria, most common in those <5years in the rectum, causing bleeding.

Question 20

What is the inheritance pattern of Peutz-Jeghers syndrome?

Answer 20

Autosomal dominant

Question 21

Name the gene affected in Peutz-Jeghers syndrome

Answer 21

LKB1

Question 22

Describe the features of Peutz-Jeghers syndrome

Answer 22

Multiple colonic hamartomatous polyps, mucocutaneous hyperpigmentation, freckles around the mouth, palms, and soles. Increased risk of intussusception and malignancy so require regular surveillance of GI tract, pelvis, and gonads

Question 23

What is the peak age group for hyperplastic polyps?

Answer 23

50-60years

Question 24

What % of colorectal cancers are adenocarcinomas?

Answer 24

98%

Question 25

What is the peak age group for colorectal cancer?

Answer 25

60-79 years

Question 26

State at least 3 risk factors for colorectal cancer

Answer 26

Low-fibre high-fat diet, lack of exercise, obesity, familial syndromes, chronic inflammatory bowel disease

Question 27

State a protective factor for colorectal cancer

Answer 27

NSAIDs

Question 28

Name an enzyme over-expressed by 90% of colorectal cancers

Answer 28

COX-2

Question 29

Describe the clinical features of right-sided colorectal tumours

Answer 29

Iron deficiency anaemia, weight loss

Question 30

Describe the clinical features of left-sided colorectal tumours

Answer 30

Change in bowel habit, crampy left lower quadrant pain

Question 31

Name the tumour marker used to monitor colorectal cancer

Answer 31

Carcinoembryonic antigen (CEA)

Question 32

Name the staging system for colorectal cancer

Answer 32

Duke's staging

Question 33

Describe the stages of colorectal cancer

Answer 33

A: confined to mucosa B1: extending into muscularis propria B2: transmural invasion, no lymph nodes involved C1: extending to muscularis propria, lymph node metastases C2: transmural invasion, lymph node metastases D: distant metastases

Question 34

State the 5-year survival for stage A and D colorectal cancer

Answer 34

A: >95% D: <10%

Question 35

Describe the management of colorectal cancer

Answer 35

Surgical resection with post-op radiotherapy

Question 36

Name the chemotherapeutic agent used in palliative chemotherapy for colorectal cancer

Answer 36

5-fluorouracil

Question 37

State the two causes of familial adenomatous polyposis

Answer 37

70%: autosomal dominant mutation in APC gene on chromosome 5q1 30%: autosomal recessive mutation in DNA mismatch repair genes

Question 38

How many adenomatous polyps are required to diagnose familial adenomatous polyposis (FAP)?

Answer 38

>100

Question 39

How is familial adenomatous polyposis managed?

Answer 39

Prophylactic colectomy - otherwise will get adenocarcinoma by 30

Question 40

What is Gardner's syndrome?

Answer 40

Familial adenomatous polyposis + osteomas and dental caries

Question 41

State two places other than the colon and rectum where those with FAP are at increased risk of malignancy

Answer 41

Ampulla of Vater, stomach

Question 42

What is Lynch syndrome?

Answer 42

Hereditary non-polyposis colorectal cancer (HNPCC), autosomal dominant mutations in DNA mismatch repair genes causing carcinomas in the right colon <50 years of age

Question 43

State at least two malignancies other than colorectal cancer associated with Lynch syndrome

Answer 43

Endometrial, ovarian, small bowel, transitional cell, stomach