Inflammatory Bowel Disease Pathology

Question 1

Describe aetiology and pathogenesis of IBD.

Answer 1

• Exact trigger unknown
• 3 possible interactive factors - genetic, environmental and host factors

Question 2

Describe some symptoms of IBD.

Answer 2

• Profuse watery diarrhea with blood, mucus, and pus
• Abdominal pain; and hematochezia (bright red blood per rectum).
• Pyoderma gangrenosum initially presents similar to cellulitis but fails to respond to antibiotics; typically causes deep ulceration with a violaceous border.

Question 3

How can IBD be diagnosed?

Answer 3

• Loss of haustra in barium enema
• Colonscopy with biopsy

Question 4

Describe the difference in inflammation pattern and distribution in crohn’s and UC.

Answer 4

• Crohn’s - Discontinuous distribution
• UC - Continuous distribution

Question 6

Define Crohn’s.

Answer 6

Idiopathic inflammatory bowel disease characterized by multifocal areas of inflammation which may involve any part of the gastrointestinal tract

Question 7

Describe possible aetiologies of Crohn’s.

Answer 7

• Increased risk with smoking
• Abnormal mucosal immune response to bacteria in genetically susceptible individuals
• Mutations in CARD15 gene - associated with Crohn’s
• True aetiology remains unproven

Question 8

Describe gross findings in Crohn’s.

Answer 8

• Disease usually involves the terminal ileum and colon.
• Affected bowel is thickened with encroachment of mesenteric fat around the anti-mesenteric border of the bowel (‘fat wrapping’).
• Adhesions and fistulas may be seen between adjacent loops of bowel.
• The mucosal shows linear ulceration and cobblestone appearance

Question 9

What are 3 other gross findings of Crohn’s?

Answer 9

Skipped lesions
Bowel wall thickening
Stricture formation

Question 10

What are fistulas?

Answer 10

Inflammatory abnormal connections between different structures

Question 12

Describe microscopic findings of Crohn’s. PART 1

Answer 12

• Inflammation within a single biopsy and between several biopsies is the key feature.
• Typically manifested by discrete areas of inflammation adjacent to histologically normal crypts.
• Transmural Inflammation (Lymphoid aggregates are present in the submucosa and muscular layers).

Question 13

Describe microscopic findings of Crohn’s. PART 2

Answer 13

• Poorly formed granulomas may be seen, but generally uncommon.
• Deep fissuring ulcers separated by relatively normal mucosa.

Question 14

Describe the prognosis of Crohn’s.

Answer 14

• Relapsing and remitting course.
• Require surgery at some point to relieve symptoms: obstruction or fistula formation.
• Increased risk of bowel cancer.
• Extra gastrointestinal manifestations include enteropathic arthropathy, anterior uveitis, gallstones, erythema nodosum, and pyoderma gangrenosum.

Question 15

List some complications of Crohn’s

Answer 15

• Psychosocial impact (e.g. on school, work or leisure)
• Intestinal complications: strictures, fistulas, dilation, perforation and haemorrhage
• Perianal disease
• Anaemia
• Malnutrition, faltering growth or delayed pubertal development
• Cancer of the small and large intestine

Question 16

What is UC?

Answer 16

Idiopathic inflammatory bowel disease characterised by inflammation restricted to the large bowel mucosa, which always involves the rectum and extends proximally in a continuous fashion for a variable distance.

Question 17

Describe the aetiology of UC.

Answer 17

• Thought to be due to an abnormal mucosal immune response to luminal bacteria.
• The genetic link is weaker than for Crohn’s disease.
• Smoking appears to decrease the risk of ulcerative colitis (UC).
• Protective effect of appendectomy on development of UC.

Question 18

What are the gross findings in UC?

Answer 18

• Erythematous mucosa with a friable eroded surface and haemorrhage.
• Inflamed mucosa may form polypoid projections (inflammatory pseud-polyps).
• Disease always involves the rectum and extends continuously to involve a variable amount of colon.

Question 19

What are the microscopic findings in UC? PART 1

Answer 19

• Diffuse mucosal inflammation with cryptitis, crypt abscess formation and crypt distortion
• Inflammation more severe distally

Question 20

What are the microscopic findings in UC? PART 2

Answer 20

• Diffuse inflammation limited to mucosal layer
• Inflammatory pseudo-polyps or ulceration may be present
• VERY SEVERE ACUTE UC - extension of inflammation into submucosa or muscle layers

Question 20

List some complications of UC

Answer 20

Severe bleeding
Bowel perforation
Toxic megacolon
Malnutrition
Venous thromboembolism
Osteoporosis
Colorectal cancer

Question 21

Describe general prognosis of UC.

Answer 21

• Generally good with treatment.
• Increased risk of colorectal carcinoma, so surveillance colonoscopy is usually recommended several years after diagnosis.