Inflammatory Bowel Disease Pathology Flashcards
Describe aetiology and pathogenesis of IBD.
- Exact trigger unknown
- 3 possible interactive factors - genetic, environmental and host factors
Describe some symptoms of IBD.
- 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.
How can IBD be diagnosed?
- Loss of haustra in barium enema
- Colonscopy with biopsy
Describe the difference in inflammation pattern and distribution in crohn’s and UC.
- Crohn’s - Discontinuous distribution
- UC - Continuous distribution
Define Crohn’s.
Idiopathic inflammatory bowel disease characterized by multifocal areas of inflammation which may involve any part of the gastrointestinal tract
Describe possible aetiologies of Crohn’s.
- 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
Describe gross findings in Crohn’s.
- 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
What are 3 other gross findings of Crohn’s?
Skipped lesions
Bowel wall thickening
Stricture formation
What are fistulas?
Inflammatory abnormal connections between different structures
Describe microscopic findings of Crohn’s. PART 1
- 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).
Describe microscopic findings of Crohn’s. PART 2
- Poorly formed granulomas may be seen, but generally uncommon.
- Deep fissuring ulcers separated by relatively normal mucosa.
Describe the prognosis of Crohn’s.
- 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.
List some complications of Crohn’s
- 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
What is UC?
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.
Describe the aetiology of UC.
- 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.
What are the gross findings in UC?
- 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.
What are the microscopic findings in UC? PART 1
- Diffuse mucosal inflammation with cryptitis, crypt abscess formation and crypt distortion
- Inflammation more severe distally
What are the microscopic findings in UC? PART 2
- 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
List some complications of UC
Severe bleeding
Bowel perforation
Toxic megacolon
Malnutrition
Venous thromboembolism
Osteoporosis
Colorectal cancer
Describe general prognosis of UC.
- Generally good with treatment.
- Increased risk of colorectal carcinoma, so surveillance colonoscopy is usually recommended several years after diagnosis.
