Lecture 20 Alimentary Tract Pathology

Question 1

Small bowel and large bowel peristalsis is mediated by what neural control

Answer 1

Intrinsic (myenteric plexus) and extrinsic (autonomic innervation) neural control

Question 2

Where is the Meissener’s plexus located

Answer 2

Base of submucosa

Question 3

Where is the Auerbach plexus located

Answer 3

Between the inner circular and outer longitudinal layers of the muscular propria

Question 4

Whats the main difference between ulcerative colitis and Crohn’s

Answer 4

Crohn’s can affect any part of the GIT from mouth the anus

UC is limited to colon

Question 5

What is the aetiology of IBD

Answer 5

• Strong immune response against normal flora with defects in the epithelial barrier function in genetically susceptible individuals

Question 6

What gene mutation is seen in Crohn’s disease

Answer 6

NOD2

Question 7

What gene mutation is seen in Ulcerative colitis

Answer 7

HLA

Question 8

What is UC called when it is localised in the rectum

Answer 8

Proctitis

Question 9

Describe the pathology of UC

Answer 9

• Large bowel only
• Continuous pattern of inflammation.
• Rectum to proximal
• Pseudopolyps
• Ulceration
• Serosal surface minimal or no inflammation

Question 10

Histology of UC

Answer 10

Inflamed mucosa
Cryptitis
Crypt abscesses
Disarray of crypts
Mucosal atrophy
Ulceration into submucosa
No granulomas 
Submucosal fibrosis
Reactive atypic/dysplasia

Question 11

Complications of UC

Answer 11

 Haemorrhage
 Perforation
 Toxic dilatation

Question 12

Describe pathology of Crohn’s disease

Answer 12

Granular serosa
Mesentery thickened, oedema and fibrotic
Narrowing of lumen
Skip lesions
Ulceration- cobble stone

Question 13

Describe the histology of Crohn’s disease

Answer 13

• Cryptitis and crypt abscesses
• Architectural distortion
• Atrophy –crypt destruction
• Ulceration-deep
• Transmural inflammation
• Chain of pearls
• Non-caseating granulomas
• Fibrosis
• Lymphangiectasia
• Hypertrophy of mural nerves
• Paneth cell metaplasia

Question 14

Long term features of CD

Answer 14

• SI – malabsorption
• Strictures
• Fistulas and abscesses
• Perforation
• Increased risk of cancer

Question 15

What is Ischaemic Enteritis

Answer 15

Occlusion of SI or LI major soppy vessels

Question 16

Predisposing Conditions for Ischaemia

Answer 16

Arterial thrombosis
Arterial embolism
Non-occlusive ischaemia

Question 17

Histology of Acute Ischaemia

Answer 17

• Oedema
• Interstitial haemorrhages
• Sloughing necrosis of mucosa-ghost outlines
• Nuclei indistinct
• Initial absence of inflammation
• 1-4 days –bacteria-gangrene and perforation
• Vascular dilatation

Question 18

Features of Chronic ischaemia

Answer 18

• Mucosal inflammation
• Ulceration
• Submucosal inflammation
• Fibrosis
• Stricture

Question 19

Define Radiation Colitis

Answer 19

• Abdominal irradiation can impair the normal proliferative activity of the small and large bowel epithelium

Question 20

Symptoms of radiation colitis

Answer 20

Anorexia, abdominal cramps, diarrhoea and malabsorption

Question 21

Histology of radiation colitis

Answer 21

• Bizarre cellular changes
• Inflammation-crypt abscesses and eosinophils
• Later-arterial stenosis
• Ulceration
• Necrosis
• Haemorrhage
• perforation

Question 22

Causes of appendicitis

Answer 22

Obstruction
Enterobius vermicularis
Intraluminal pressure leading to ischaemia

Question 23

Histology of appendicitis

Answer 23

Macro-fibrinopurulent exudate, perforation, abscess
• Acute suppurative inflammation in wall and pus in lumen
• Acute gangrenous-full thickness necrosis +/- perforation

Question 24

Colorectal adenocarcinoma right sided

Answer 24

exophytic/polypoid
Anaemia- altered blood pH
Vague pain
Weakness
Obstruction

Question 25

Colorectal adenocarcinoma left sided

Answer 25

Annular- napkin ring lesion
Bleeding- fresh altered blood PR
Altered bowel habit
Obstruction