Pathology of the small bowel

Question 1

What can cause ischaemia of the small bowel?

Answer 1

Mesenteric arterial occlusion

1. Mesenteric artery atherosclerosis
2. Thromboembolism from heart (e.g. A.Fib)

Non occlusive perfusion insufficiency

1. Shock
2. Strangulation obstructing venous return (e.g. hernia, adhesion)
3. Drugs e.g. Cocaine
4. Hyperviscosity

Question 2

How does small bowel infarct change with length of infarct?

Answer 2

mucosal infarct
mural infarct
transmural infarct

Question 3

What is the outcome of mucosal infarct?

Answer 3

regeneration

Question 4

What is the outcome of mural infarct?

Answer 4

repair and regeneration

Question 5

What is the out come of transmural infarct?

Answer 5

gangrene (death if not resected)

Question 6

What are the complications of ischaemic small bowel?

Answer 6

Gangrene 
perforation
peritonitis
sepsis
death

Question 7

What is Meckel’s Diverticulum?

Answer 7

Result of incomplete regression of vitello-intestinal duct
Tubular structure, 2 inches long, 2 foot above IC valve

May contain heterotopic gastric mucosa
May cause bleeding, perforation or diverticulitis which mimicks appendicitis

Question 8

Describe lymphomas of the small bowel and their treatment?

Answer 8

Rare all Non Hodkins in type
Maltomas (B-cell) derived
Intestinal disease associated T-cell lymphomas (associated with Coeliac disease)

Treated by surgery and chemotherapy

Question 9

Describe carcinomas of the small bowel?

Answer 9

commonest site is the appendix
Small, yellow ,slow growing tumours
Locally invasive
Can cause intussusception, obstruction
Produce hormone like substances
If metastases to liver occur a Carcinoid syndrome occurs producing flushing and diarrhoea
Associated with Crohn’s disease and Coeliac disease
Identical to colorectal carcinoma in appearance

Question 10

What are the causes of acute appendicitis?

Answer 10

Unknown
Faecoliths (dehydration)
Lymphoid hyperplasia
Parasites
Tumours (rare)

Question 11

Describe the pathology of acute appendicitis?

Answer 11

Acute inflammation (neutrophils)
Mucosal ulceration
Serosal congestion, exudate
Pus in lumen

Question 12

What are the complications of acute appendicitis?

Answer 12

Peritonitis
Rupture
Abscess
Fistula
Sepsis and liver abscess

Question 13

Describe coeliac disease?

Answer 13

Strong association with HLA-B8

Strong association with dermatitis herpetiformis

Question 14

What is the cause of coeliac disease? What mediated the reaction?

Answer 14

Gliadin a component of gluten is the suspected toxic agent

But tissue injury may be a bystander effect of abnormal immune reaction to Gliadin

Mediated by T-cell lymphocytes which exist within the small intestinal epithelium ‘intraepithelial lymphocytes’ (IELS)

Question 15

What occurs to the mucosa in coeliac disease?

Answer 15

Increasing loss of enterocytes due to IEL mediated damage
-> leads to loss of villous structure, loss of surface area,
a reduction in absorbtion and a flat duodenal mucosa

Question 16

What is present in the serology of coeliac disease?

Answer 16

Antibodies

anti-TTG, anti-endomesial, anti-gliadin

Question 17

Describe the metabolic effects of coeliac disease?

Answer 17

Malabsorbtion of sugars, fats, amino acids, water and electrolytes

Reduced intestinal hormone production leads to reduced pancreatic secretion and bile flow (CCK) leading to gallstones

Question 18

What are rare complications of coeliac disease?

Answer 18

T-cell lymphomas of GI tract
Increased risk of small bowel carcinoma
Gall stones
Ulcerative-jejenoilleitis