Pathology of Small Bowel

Question 1

What are the 2 occlusive causes of infarction in the small bowel?

Answer 1

Mesenteric artery atherosclerosis

Thromboembolism from the heart (Eg. A fib)

Question 2

What are the 4 non-occlusive causes of infarction on the small bowel?

Answer 2

shock
strangulation obstructing venous return (eg. hernia adhesion)
Drugs (cocaine)
Hyperviscosity (precipitates thrombus)

Question 3

is bowel ischaemia acute or chronic?

Answer 3

usually acute but can be chronic

Question 4

What is the pathogenesis of bowel ischaemia?

Answer 4

Mucosa = most metabolically active so highest oxygen demand so most sensitive to hypoxia, where necrosis begins
The longer the period of ischaemia, the deeper the damage to the bowel wall and the more complications
Most tissue damage occurs after reperfusion in non-occlusive ischaemia

Question 5

what are the consequences of mucosal, mural and transmural infarction?

Answer 5

mucosal = bowel will heal itself
Mural = repair with fibrous scarring
Transmural = death/gangrene if not surgically removed

Question 6

what do mucosal, mural and transmural infarction look like?

Answer 6

mucosal looks normal
mural = red and swollen (like sausages)
Transmural = dark red/black, very swollen

Question 7

what might be seen in the histology of a mucosal infarction?

Answer 7

pus, fibrin, blood, neutrophils, haemorrhage

Question 8

what are the 3 possible outcomes of small bowel ischaemia?

Answer 8

complete resolution
fibrosis, stricture, chronic ischaemia, mesenteric angina, obstruction
Gangrene, perforation, peritonitis, sepsis, death

Question 9

What is Meckel’s Diverticulum?

Answer 9

Rare congenital disorder where the vitello-intestinal duct doesn’t disappear during development as its supposed to
2” long tube 2 foot above ileocaecal valve
May contain heterotropic gastric mucso

Question 10

what are the symptoms of Meckels Diverticulum?

Answer 10

usually asymptomatic

Can cause bleeds, peptic ulcers, perforation or diverticulitis which mimics appendicitis

Question 11

Primary tumours of the small bowel are common, true or false?

Answer 11

False

Primary tumours are rare due to stable epithelium, secondary tumours are common

Question 12

What type of seconday tumours are common in the small bowel?

Answer 12

Ovary
Colon
Stomach

Question 13

What 3 types of primary tumour can arise in the small bowel?

Answer 13

Lymphomas
Carcinoid tumours
Carcinomas (rare)

Question 14

Describe lymphomas of the small bowel and how they are treated

Answer 14

All non-hodgkins
maltomas (B cell) derived
Enteropathy (eg coeliac disease) associated T cell lymphomas
Treated with surgery and chemo

Question 15

Where do carcinoid tumours most commonly arise and what do they do?

Answer 15

Appendix
Small, yellow, slow growing, locally invasive tumours that produce hormone like substances (eg serotonin like) that produce systemic effects (eg carcinoid syndrome if metastases to liver = flushing and diarrhoea)

Question 16

what type of primary small bowel cancer is associated with chrons disease and coeliac disease?

Answer 16

carcinomas

Question 17

What cancer does small bowel carcinoma resemble in terms of appearance?

Answer 17

colorectal carcinoma

Question 18

at what stage does small bowel carcinoma usually present and where does it commonly metastases to?

Answer 18

presents in late stage

Often metastases to liver and lymph nodes

Question 19

How does appendicitis present and what age is it more common at?

Answer 19

vomiting
abdominal pain
Right iliac fossa tenderness
Increased white cell count
More common in children but can happen in adults

Question 20

What can cause appendicitis?

Answer 20

idiopathic
faecoliths (dehydration)
lymphoid hyperplasia
Parasites
Tumours (rare)

Question 21

What are the 4 pathological changes that occur in appendicitis?

Answer 21

Acute inflammation (neutrophils) - MUST INVOLVE MUSCLE COAT - muscle wall is thickened
Mucosal ulceration
Serosal congestion, exudate
Pus in lumen

Question 22

How can the appendix burst?

Answer 22

Neutrophils spread through the muscular wall and liberate their contents into the muscularis externa causing it to dissolve
Appendix wall becomes perforated and can burst if surgery not performed

Question 23

What possible complications can arise from appendicitis?

Answer 23

Peritonitis
Rupture
Abscess
Fistula
Sepsis and liver abscess

Question 24

what is coeliac disease?

Answer 24

abnormal reaction to a constituent of wheat flour, gluten, which damages enterocytes and reduces absorptive capacity

Question 25

name 3 things coeliac disease is associated with

Answer 25

Childhood diabetes
HLA-B8 (MHC class 1)
dermatitis herpetiformis

Question 26

What is the trend in coeliac disease incidence?

Answer 26

Increasing

Question 27

What causes coeliac disease?

Answer 27

Intraepithelial Lymphocyte (T cell) mediated hypersensitivity to Gliadin component of gluten causing tissue damage

Question 28

What physical changes occur in the mucosa of coeliac people?

Answer 28

Loss of enterocytes due to IEL mediated damage leading to loss of villi causing a flat mucosa and therefore a reduction in surface area

Question 29

What histology can be seen in coeliac disease?

Answer 29

Flat mucosa with villous atrophy
Increased inflammation in lamina propria
Increased intraepithelial lymphocytes

Question 30

How will be the results of clinical tests in coeliac disease?

Answer 30

Endoscopy - mucosa may be normal or attenuated
Duodenal biopsy - lesion worse in proximal bowel
Serology - antibodies: anti-TTG, anti-endomesial, anti-gliadin

Question 31

what are 2 metabolic effects of coeliac disease?

Answer 31

malabsorption of sugars, fats, amino acids, water and electrolytes
Reduced intestinal hormone production leads to reduced pancreatic secretion and bile flow (CCK) which results in gall stones

Question 32

Malaborption of___ leads to steatorrhoea

Answer 32

fats

Question 33

List 5 consequences of malabsorption

Answer 33

weight loss
anaemia (iron, B12, folate)
abdominal bloating
failure to thrive (if disease in childhood)
vitamin deficiencies