Crohn's disease and Ulcerative colitis

Question 1

Epidemiology of Crohn’s disease

Answer 1

Highly prevalent in Western world

Biomodal presentation

• Peaks in teens/20s
• Peaks in 60-70

Question 2

Genetics of Crohn’s disease

Answer 2

Strong genetic predisposition

Frameshift mutation in NOD2 gene

• The gene is responsible for inhibiting immune response to luminal microbes
• Mutation causes uncontrolled inflammation

Question 3

Infectious cause of Crohn’s disease

Answer 3

Mycobacterium paratuberculosis

• Due to presence of granulomas
• Not completely proven

Question 4

Environmental factors for Crohn’s

Answer 4

Improved hygiene hypothesis
- Mucosa not immunised to microbes.

Migrating from a low to high risk population

Smoking ciagarettes

Question 5

Clinical presentation of Crohn’s

Answer 5

Abdominal pain relived by opening bowel

Chronic courses with periods of remission and relapses

Prolonged non-bloody diarrhea

Weight loss

Question 6

Distribution of Crohn’s in the GI

Answer 6

Can affect anywhere from the mouth to anus:

• Mainly small bowel alone
• Affects large bowel and small+large equally

Question 7

Morphological features of Crohn’s

Answer 7

Fat wrapped around serosa

Segmented inflammation- skipped lesions

Ulceration forms cobblestone pattern

Strictures formed from fibrosis

Question 8

Microscopic appearance of Crohn’s

Answer 8

Transmural inflammation of bowel

Mixed inflammation:

• Chronic and acute
• Contains polymorphs and lymphocytes

Crypts are preserved

Fissuring ulcers

Granuloma common in 60-65% of cases

Fibrotic gut wall.

Question 9

Complications from Crohn’s

Answer 9

Fistulas from deep ulcers

Sinus tract- blind ended tract

Obstruction from adhesions and strictures

Perianal fistula and sinuses

Risk of adenocarcinoma (lower than UC)

Question 10

Epidemiology of Ulcerative colitis

Answer 10

Most common in western countries

Rare before age 10.

• Peaks 20-25
• Smaller peak 55-65

Question 11

Environmental factors and UC

Answer 11

Smoking is protective

Exacerbated by NSAIDs

Possibly associated with low Vit a and E

Question 12

Clinical features of UC

Answer 12

Intermittent bloody diarrhea/ mucoid diarrhea

Abdominal pain

Weight loss

Low grade fever

Question 13

Macroscopic features of UC

Answer 13

Affects any part of large bowel only:

• Proctitis (rectum only)
• Left bowel
• Total colitis

No ulcers in early disease

Bowel shortens and mucosa flattens

Question 14

Microscopic features of UC

Answer 14

Inflammation of the mucosa ONLY

Mixed inflammation

Crypt architecture distortion

Question 15

Complications of UC

Answer 15

Toxic megacolon- very dilated bowel

Refractory bleeding

Dysplasia/ adenocarcinoma

Question 16

Ocular extra-intestinal presentation of CD and UC

Answer 16

Uveitis

Iritis

Episcleritis

Question 17

Cuntaneous extra-intestinal presentation of CD and UC

Answer 17

Erythema nodosum

Pyoderma gangrenosum

Question 18

Investigations for CD and UC

Answer 18

C-reactive proteins

Endoscopy and biopsy

Radiological imaging

• Barium
• MRI
• USS
• CT

Question 19

Differences between CD and UC

• Obstruction
• Fistula
• Weight loss
• Perianal disease
• Distribution
• Pathology
• Cancer risk
• Smoking

Answer 19

Obstruction
- More common in CD

Fistula:
- Seen in CD but not UC

Weight loss:
- Common in CD, not as much in UC

Perianal disease:
- Much more common in CD

Distribution:

• CD affects anywhere in the gut in skipped lesions.
• UC only affects large bowel continuously

Pathology:

• UC is mucosal only with no ulcers, granulomas
• CD is transmural with fissuring ulcers, granulomas
• Crypts are distorted in UC but preserved in CD.

Cancer:
- UC has higher risk that CD

Smoking:
- Makes CD worse, but UC better.