Pathology of the Small Bowel

Question 1

What are the 2 main causes of ischaemia of the small bowel>

Answer 1

1. Mesenteric arterial occlusion.

2. Non-occlusive perfusion insufficiency.

Question 2

What can cause mesenteric arterial occlusion?

Answer 2

Mesenteric artery atherosclerosis or thromboembolism from the heart.

Question 3

What are the causes of non-occlusive perfusion deficiency?

Answer 3

Shock, strangulation obstructing venous return (e.g. hernia, adhesion), drugs (e.g. cocaine due to vasospasm) and hyperviscosity.

Question 4

Can you get chronic bowel ischaemia?

Answer 4

Yes but it is usually acute.

Question 5

What is the part of the bowel most sensitive to the effects of hypoxia and why?

Answer 5

The mucosa as it is the most metabolically active part of the bowel wall.

Question 6

When does much of the tissue damage occur after reperfusion?

Answer 6

In non-occlusive ischaemia.

Question 7

What are the progressing degrees of infarct that occur as time of infarction progresses?

Answer 7

Mucosal, mural then transmural.

Question 8

What are the potential outcomes/complications of acute small bowel ischaemia?

Answer 8

Resolution; fibrosis, stricture (narrowing), chronic ischaemia, mesenteric angina and obstruction; gangrene, perforation, peritonitis, sepsis and death.

Question 9

What causes a Meckel’s diverticulum to form?

Answer 9

Incomplete regression of vitello-intestinal tract.

Question 10

How long, whereabouts and what percentage of people will have a Meckel’s diverticulum?

Answer 10

2 inches long, 2 foot above IC valve and 2% of people.

Question 11

What type of mucosa may Meckel’s diverticulum contain?

Answer 11

Heterotopic gastric mucosa.

Question 12

What can be the negative complications of Meckel’s diverticulum?

Answer 12

Bleeding, perforation or diverticulitis (mimics appendicitis).

Question 13

Why are primary tumours of the small bowel rare?

Answer 13

High turnover of cells being lost to the body.

Question 14

Where do metastases commonly invade the small intestine from?

Answer 14

Ovary, colon, stomach.

Question 15

What are the types of primary tumours of the small bowel from most to least common?

Answer 15

Lymphomas, carcinoid tumours (neuroendocrine tumours), carcinomas.

Question 16

What types of lymphomas occur in the small bowel?

Answer 16

Non-Hodgkin’s.

Question 17

What is a maltoma?

Answer 17

A B-cell derived lymphoma.

Question 18

What disease are T-cell lymphomas associated with?

Answer 18

Coeliac disease.

Question 19

How are lymphomas of the small bowel treated?

Answer 19

By surgery or chemotherapy.

Question 20

Where is the commonest site of carcinoid tumours in the bowels?

Answer 20

The appendix.

Question 21

What do carcinoid tumours look like?

Answer 21

Small, yellow (and slow growing).

Question 22

Are carcinoid tumours locally invasive?

Answer 22

Yes.

Question 23

What adverse effects can carcinoid tumours have?

Answer 23

They cause intussusception (part of the intestine folds into the section next to it), obstruction, can produce hormone like substances.

Question 24

If a carcinoid tumour metastasises to the liver, what can it cause and what are the symptoms of this?

Answer 24

Carcinoid syndrome, flushing and diarrhoea.

Question 25

What diseases is carcinoma of the small bowel associated with?

Answer 25

Crohn’s disease and Coeliac disease.

Question 26

What is a carcinoma of the small bowel identical in appearance to?

Answer 26

Colorectal carcinoma.

Question 27

When would a carcinoma of the small bowel present?

Answer 27

Late.

Question 28

Where can a carcinoma of the small bowel metastasise to?

Answer 28

Lymph nodes and liver.

Question 29

What are the signs and symptoms of appendicits?

Answer 29

Vomiting, abdominal pain, RIF (right iliac fossa) tenderness and increased WCC (white cell count).

Question 30

What is the possible aetiology of appendicitis?

Answer 30

Unknown, faecoliths (due to dehydration), lymphoid hyperplasia, parasites, tumours (rare).

Question 31

What would you see in a pathological specimen of appendicitis?

Answer 31

Acute inflammation (neutrophils), mucosal ulceration, serosal congestion and exudate, pus in lumen.

Question 32

What layer of the appendix must acute inflammation involve?

Answer 32

The muscle coat.

Question 33

What are the complications of appendicitis?

Answer 33

Peritonitis, rupture, abscess, fistula, sepsis and liver abscess.

Question 34

In what area is coeliac disease more prevalent?

Answer 34

The west of Ireland.

Question 35

What conditions is coeliac disease associated with?

Answer 35

Dermatitis herpetiformis, childhood diabetes.

Question 36

What are the metabolic effects of coeliac disease?

Answer 36

Malabsorption of sugars, fats (leads to steatorrhea), amino acids, water and electrolytes.
Reduced intestinal hormone production leads to reduced pancreatic secretion and bile flow (leads to gallstones).

Question 37

What are the effects of malabsorption on the patient?

Answer 37

Weight loss, anaemia, abdominal bloating, failure to thrive, vitamin deficiencies.

Question 38

What are rarer complications of coeliac disease?

Answer 38

T-cell lymphoma of GI tract, increased risk of small bowel carcinoma, gall stones, ulcerative-jejunoilleitis.