Pathology of the Colon

Question 1

I left most of this lecture out as it was repeated in better detail in the IBD and CRC lectures later on.

Answer 1

This stuff is just what wasn’t included elsewhere

Question 2

What is ischaemic enteritis?

Answer 2

Occluded vessel leads to ischaemic lesions in the gut with location depending on the involved vessel

Question 3

What happens if one of the 3 major vessels of hte gut is occluded?

Answer 3

Infarction!

Question 4

What happens if one of the gut arteries is occluded gradually?

Answer 4

Very little as it the anastomotic circulation compensates

Question 5

Ischaemic enteritis can be caused by an arterial thrombosis, embolism or non-occlusive ischaemia. What are some common sources for these?

Answer 5

Thrombosis:

• Atherosclerosis
• Vasculitis
• Hypercoagulability
• Oral Contraceptive
• Dissecting Aneurysm

Embolism:

• Cardiac vegetations
• Acute Atheroembolism
• Cholesterol Embolism

Non-occlusive Embolism:

• Cardiac Failure
• Shock/dehydration
• Vasoconstrictive drugs

Question 6

How does the affected part of the gut appear during ischaemic enteritis?

Answer 6

Congestion leads to a dusky blue/purple color and sanguinous mucous in the lumin

Histologically:

• You get Oedema, Interstitial Hemorrhages & vascular dilatation due to congestion
• You also get Sloughing necrosis of the mucosa & within 1-4 days bacteria cause gangrene & perforation due to lack of blood supply causing tissue death.

Chronically you get inflammation, ulceration and fibrosis/strictures.

Question 7

What is radiation colitits?

Answer 7

Where abdominal irradiation impairs normal proliferative activity of the bowel epithelium

Question 8

What is the presentation of radiation colitis?

Answer 8

Anorexia
Abdominal cramps
Diarrhoea
Malabsorption

The damage depends on the dose and location

Chronically it mimics IBD

Question 9

How does radiation colitis appear histologically?

Answer 9

• Nuclear hypertrophy
• Inflammation causing crypt abscesses & eosinophils

Chronically or in large doses it can also cause:

• Arterial stenosis
• Ulceration
• Necrosis
• Haemorrhage
• Perforation

Question 10

What causes appendicitis?

Answer 10

Infection - Often via a stomach or other GI infection

Obstruction, most often due to feocolith or enterobius vermicularis (giant roundworm)

Question 11

Waht is a feocolith?

Answer 11

A stone of faecaes often with calcification caused by faecal impaction.

When it occurs in the appendix its called appendicolith

Question 12

How does appendicitis present?

Answer 12

Poorly localised colic pain progressing to sharp pain in right iliac fossa
N&V
Diarrhoea
 Anorexia
Fever

Question 13

MAnagement of appendicitis?

Answer 13

Appendectomy