Pathology -- Autoimmune Diseases Flashcards
Define MALT
Mucosa Associated Lymphoid Tissue = a specialized immune system which protects mucosal surfaces (i.e. GIT, bronchial tree, nasopharynx, GU tract)
Role of MALT in the GIT
- Absorption of nutrients
- Need and effective barrier and a selective response (innate and acquired immune system) to various substances (harmless vs. harmful)
What constitutes an effective barrier in the mucosal immune system
Intact intestinal epithelium (surface mucosa, peristalsis, protective secretory factors)
Define the innate immune system
Initial response to antigen exposure (neutrophils, macrophages, NKCs)
Define the adaptive immune system
Specific immuntiy to antigens (APCs with molecules of the major histocompatibility complex) = self from non-self
i.e. B and T lymphocytes, dendritic cells
One hypothetical equation to explain the cause of IBD
5 risk factors for IBD
- Age = young
- Ethnicity = Causacians (particularly Ashkenazi Jews)
- Family history
- Geography = US and Europe
- Smoking
Incidence of IBD
CD = 16.9 per 100,000
UC = 12.9 per 100,000
Provinces with the highest incidence of IBD
QC and NS
Prevalence of IBD in Canada
0.7% (233,000)
Describe the role of family history in the risk of developing IBD
1st degree relative = 12 - 25% risk
Monozygotic twins = 60% concordance
Describe the role of smoking in the risk of developing IBD
Active smokers are more than 2 times as likely to develop CD than nonsmokers, but less likely to develop UC (smoking is actually protective??)
How is IBD diagnosed?
Clinical diagnoses relying on:
- Clinical history (symptoms)
- Laboratory findings
- Endoscopic features
- Histological evaluation
- Radiographic evaluation
- Rulling out infectious etiologies
4 lab tests for IBD
- Tests for anemia
- B12 deficiency
- Increased CRP
- Fecal calprotectin
3 endoscopic methods for diagnosing IBD
- Gastroscopy
- Colonoscopy
- Capsule endoscopy
3 radiographic evaluation tools for diagnosing IBD
SBFT or CT or MR enterography
2 subsets of IBD
Crohn’s disease
Ulcerative colitis
7 characteristics of Crohn’s disease
- Chronic inflammatory disease
- Affects any segment of the luminal GIT (mouth -> anus)
- Transmural involvement
- Rectum usually spared
- Sharply delineated areas affected with intervening normal bowel (“skip areas”)
- Noncaseating granulomas
- Fistulization
Describe the anatomical distribution of CD
4 clinical patterns of CD
+ Fistulae and abscesses
2 general clinical features of CD
- Intermittent diarrhea and abdominal pain
- GI bleeding
3 chronic clinical features of CD
- Strictures
- Fistulas
- Malabsorption
7 morphological features of CD
- Mucosal erythema/edema
- Superficial ulcers
- Deep linear ulcers on axis
- Nodularity from skip areas (cobblestoning)
- Bowel wall thickens, lumen narrows (string sign)
- Edematous mesentery (creeping fat)
- Extension of fissuring (fistulae, abscesses, adhesions, perforations)
5 histologic features of CD
- Mucosal inflammation
- Chronic mucosal damage
- Ulceration (abrupt)
- Transmural inflammation
- Granulomas (10 - 30%)
- Thickening/fibrosis
Describe the mucosal inflammation of CD
Crypt abscesses
3 features of chronic mucosal damage seen histologically in CD
- Glandular distortion
- Pyloric metaplasia
- Paneth cell metaplasia
How does CD progress anatomically over time?
Location remains stable over time (note that 1/3 have penetrating/stricturing complications)
How common is prolonged remission in CD
Only 10% within 10 years
4 complications of CD
- Annual incidence of hospitalization = 20%
- Steroid dependency = 33%
- Surgery post diagnosis = 50% within 10 years
- Post-operative recurrence = 50% within 10 years
7 characteristics of UC
- Chronic inflammatory disease
- Affects the colorectum (may be whole colon = pancolitis)
- Generally restricted to the mucosa
- Rectal involvement
- Contiguous to varying extent
- 10% with “backwash ileitis”
- No granulomas
Describe the therapy for CD
Top down therapy:
Describe the anatomic distribution of UC
Describe the clinical features of UC
A spectrum of effects based on disease progression where:
- Proctitis = mild
- Left-sided colitis = moderate
- Pancolitis = severe
5 mild clinical features of UC
- Intermittent bleeding
- Fewer stools daily
- Mucous
- Tenesmus
- Constipation
3 moderate clinical features of UC
- More bleeding
- More daily stools
- Left-sided cramps
5 severe clinical features of UC
- Significant bleeding
- Frequent stools
- Increasing pain
- Fevers
- Megacolon
When can toxic megacolon occur?
- Most severe cases of UC
- Corhn’s colitis