inflammation of GI tract - IBD W7 Flashcards
IBD is the collective name for which 2 conditions?
ulcerative colitis
Crohn’s disease
aetiology of IBD?
not fully understood!
inherited susceptibility
immunological abnormalities
environmental factors
loss of tolerance to normal commensal bacteria
what is the greatest risk factor for IBD?
family member with IBD
smoking in Crohn’s disease vs ulcerative colitis?
makes Crohn’s disease worse
makes ulcerative colitis better
colonoscopy biopsies allow what
initial diagnosis of IBD to be made, exclude other causes eg infection.
distinguish between UC and Crohn’s
assess response to treatment
assess for complications or other pathology
surveillance for dysplasia
where to biopsy for IBD?
ideally multiple sites as distribution of inflammation in colon distinguishes Crohn’s from UC
pathological features seen in IBD biopsies - epithelium?
epithelial damage/erosion/ulceration
mucin depletion
neutrophil infiltration
metaplasia
pathological features seen in IBD biopsies - lamina propria inflammatory cell infiltrate?
cell types
density of inflammatory infiltrate
distribution of infiltrate
presence of granulomas
pathological features seen in IBD biopsies - general architecture?
surface topography eg villous change in colon
crypt architectural abnormalities, crypt atrophy
what is ulcerative colitis?
chronic relapsing and remitting condition typically presenting with recurrent episodes of rectal bleeding
UC age of presentation?
highest incidence 15-25 years, smaller peak at 60-70 years. no gender difference
where does inflammation occur in UC?
inflammation in UC confined to mucosa unless very severe
typically involves rectum and sometimes left colon.
involvement of the whole colon (pancolitis) is in a continuous distribution
features of UC mucosa?
congested, red in colour with ulceration and granular appearance. flat (indicates loss of normal mucosal fold in large bowel).
what do you tend to see endoscopically in UC?
sharp demarcation between diseased segment of bowel and normal mucosa proximal to it.
inflammatory polyps (projecting growth). broad, flat bottomed
features of UC histology?
infiltration of colonic crypts by neutrophils, formation of crypt abscesses.
features of UC polyps?
polyps are projecting growths.
present in UC - broad, flat bottomed. often pseudo polyps due to ulceration around it. don’t project deeper than submucosa.
common patterns of colonic inflammation in UC?
rectum only (proctitis)
rectum + variable length of colon in continuity
rectum + variable length of colon in continuity + discontinuous involvement of caecum and appendix (caecal patch lesion)
entire colon and rectum (pan-proctocolitis)
what is crohn’s disease?
chronic, multifocal relapsing condition that can affect any part of the GI tract
Crohn’s disease peak incidence in which age groups?
peak incidence in 20-30 with smaller peak 60-70 years. no gender difference
presenting complaint with Crohn’s?
variety of presentations depending on which part of GI involved eg
-abdominal pain
-diarrhoea
-weight loss
-strictures and obstruction
-fistulae
inflammation in Crohn’s?
patchy and discontinuous. transmural (involves all layers)
what do most cases of Crohn’s involve?
small intestine 30-35%
colon 25-30%
small intestine and colon 30-40%
anus/perianal region 50%
other parts of GI tract very uncommon
granulomas?
aggregates of activating macrophages
granulomas in Crohn’s?
present in up to 70% of cases
fewer in right than left colon
commoner in children
fewer after 2yrs
helpful in CD diagnosis when present deeper within the wall of the GI tract or within draining lymph nodes
ulceration in Crohn’s?
mildly active disease - aphthous ulcers - small superficial ulcers overlying patches of mucosa associated lymphoid tissue
Crohn’s disease GI tract appearance?
ulceration extends into anal canal and involves perianal skin
patchy distribution
in more severe disease, areas of crisscrossing linear ulceration - cobblestone mucosa
fibrosis leads to narrowing of lumen, potential stricture formation
Crohn’s disease appearance on histology?
deep knife-like fissuring ulcers that can extend all the way through muscularis propria.
can give rise to fistula - abnormal connection between hollow organs or skin surface
patches of chronic inflammation in form of lymphoid aggregates
GI complications of IBD - UC?
toxic dilation
perforation
haemorrhage
amyloidosis
neoplasia
GI complications of IBD - CD?
toxic dilation
perforation
haemorrhage
amyloidosis
neoplasia
subacute intestinal obstruction
fistulae
malabsorption (small bowel)
neoplasia in IBD?
risk increased in UC and CD (highest in UC)
risk increases with time since diagnosis, severity and extent of disease
most commonly colorectal carcinomas but also increased risk of small bowel carcinomas and other malignancies eg bile duct carcinomas, leukaemia
affects 5% of CD patients
affects 11% of UC patients
extraintestinal conditions associated with IBD?
MSK - arthritis, AS
hepatobiliary
skin disorders
oral ulceration
eye lesions
amyloid
UC vs CD - site of involvement?
UC - colon only, continuity from rectum
CD - any part of GI tract
UC vs CD - distribution of inflammation?
UC - diffuse in distribution, confined to mucosa
CD - skip lesions, transmural
UC vs CD - typical microscopic features?
UC - cryptitis, crypt abscesses, mucin depletion. crypt architectural distortion and crypt loss in chronic UC
CD - patchy inflammation, lymphoid aggregates. cryptitis and mucin cell depletion less prominent features.
UC vs CD - ulceration?
UC - broad-based ulceration which may undermine mucosa
CD - aphthous ulcers, deep fissuring ulcers
UC vs CD - granulomas?
UC - uncommon, “cryptolytic”
CD - common, may be transmural and in lymph nodes
UC vs CD - fistulae?
UC - no
CD - yes
UC vs CD - inflammatory (pseudo)polyps?
UC - yes
CD - generally fewer in number than UC but often larger
UC vs CD - other features?
UC - paneth cell metaplasia
CD - “pyloric” metaplasia in small intestine. “cobblestone” pattern from linear ulcers running in different direction
what is it important to know when diagnosing IBD?
is the patient on any medical therapy? - eg steroids. this can alter pattern and distribution of inflammation.
what happens when distinction between UC and CD is difficult?
label of IBD-U (IBD unclassified) is used
mimics of IBD?
infective colitis (bacterial and parasitic)
ischaemic colitis (most common in splenic flexure, descending colon)
diverticular disease (most common in sigmoid colon)
drug induced colitis
radiation colitis
neoplasia
causes of colonic strictures?
Crohn’s disease
ischaemic colitis
diverticular disease
diaphragm disease - NSAIDs
neoplasia
diverticular disease characterised by what?
outpouching of bowel mucosa through weak points in the wall as a consequence of high intraluminar pressure. can rupture giving rise to abscess cavities and potential fistula formation.
microscopic colitis presentation, diagnosis, pathophysiology, patterns?
usually presents as chronic watery diarrhoea
normal appearance of colonic and rectal mucosa at endoscopy (need biopsy to diagnose)
increase in chronic inflammatory cells in lamina propria
two patterns - collagenous/lymphocytic colitis
microscopic colitis causes, associations, treatment?
cause often not identified
lymphocytic colitis can be associated with coeliac disease
drugs implicated in some cases, particularly lansoprazole and NSAIDs
can be treated with steroids (budesonide)
how to make microscopic colitis diagnosis?
need biopsy because appearance of colonic and rectal mucosa is normal endoscopically!
characteristic biopsy findings in lymphocytic colitis?
presence of numerous intraepithelial lymphocytes
characteristic biopsy findings in collagenous colitis?
thick band of pink collagen within superficial lamina propria
mucosal fragility - surface epithelium detached from collagen band and lost from biopsy surface
