Pathology of IBD Flashcards
what is crohns disease?
chronic inflammatory and ulcerating condition of the GI tract thatcan affect anywhere from the mouth to anus
(most common in terminal ileum and colon)
who usually presents with crohns disease?
90% are 10-40 years old
50% 20-30 years old
can occur in children
more common in males
what are the most common sites of crohns disease?
2/3rds have small bowel involvement only
1/6 have colonic/anal disease only
1/6 have both
how does crohns disease present?
abdominal pain small bowel obstruction diarrhoea bleeding PR anaemia weight loss
what is the clinical course of crohns disease?
chronic
exacerbations and remissions
unpredictable response to therapy
small number go into lasting remission within 3 years of diagnosis
describe the typical crohns patient?
22 year old male
abdominal pain
bloody diarrhoea for 3 months
tender abdomen
how is crohns investigated?
endoscopy and mucosal biopsy
describe the pattern of lesions in crohns disease?
patchy, segmental disease with skip areas anywhere in GI tract
what does crohns look like histologically?
chronic active colitis - inflammatory cells in lamina propria
non-caseating granulomas (in 50%)
crypt branching
what are the consequences if a crohns patient doesn’t respond to medical therapy (steroids etc)?
bowel obstruction
will need surgery
what might be seen in the GI tract with crohns disease?
stricture thickened wall fat wrapping ulceration (can cause fissures) skip lesions deep knife like fissures - produces cobblestoning of mucosa pseudopolyps (rare) transmural inflammation
name 2 forms of chronic mucosal inflammation associated with crohns
cryptitis
crypt abscesses
what are the possible complications of crohns disease?
malabsorption fistulas anal disease intractable disease bowel obstruction perforation malignancy amyloidosis rarely toxic megacolon
what might cause malabsorption in crohns disease?
short bowel syndrome due to repeated resections and recurrences
hypoproteinaemia, vitamin deficiency, anaemia
gallstones
what fistulas might form in crohns disease?
VesicoColic EnteroColic GastroColic RectoVaginal TuboOvarian abscess Blind loop syndrome
what anal diseases might occur in crohns disease?
sinuses fissures skin tags abscesses perineum falls apart
what is intractable disease?
failure to tolerate or respond to medical therapy
continuous diarrhoea or pain
may require surgery - total colectomy
where is crohns disease incidence high/low?
high in north America, Europe and Scotland
low in Africa, Asia and south America
does ethnicity affect the incidence of crohns disease?
more common in jewish people than arab people in isreal
less common in Ashkenazi jews living in isreal vs the USA
is there a genetic link in crohns disease?
possibly
44% concordance in monozygous twins
possibly NOD2 gene on chromosome 16
association with HLA-DR1 and HLA-DQw5
what environmental triggers can worsen IBD?
smoking infectious agents vasculitis sterile environment theory NSAIDs
describe the aberrant immune response in crohns disease
persistent activation of T cells and macrophages (failure to switch off)
excess pro-inflammatory cytokine production
maybe alterable by changing intestinal microflora
what is the likely pathogenesis of crohns disease?
genetic susceptibility to environmental agent(s) which prevents a controlled and effective response to a trigger
what 4 things can cause crohns?
luminal microbial antigens and adjuvants
genetic susceptibility
environmental triggers
immune response
what is ulcerative colitis?
chronic inflammatory disease confined to the colon and rectum
mucosal and submucosal inflammation
UC is the most common cause of diarrhoea with pus and mucus in temperate climates, true or false?
true
who is UC most likely to present in?
young people (peaks in 30s)
more in males
can present in children/elderly
what sites does UC affect?
colon and rectum
almost always the rectum
continuous, extending proximally
what is the clinical presentation of UC?
diarrhoea
mucous and blood PR
what is the clinical course of UC?
chronic with exacerbation and remission
continuous low grade activity
a single attack
acute fulminant colitis (toxic megacolon)
describe the typical UC patient
32 yr old male
bloody diarrhoea and mucus
goes to toilet 25 times a day
how is UC investigated?
endoscopy and mucosal biopsy
what would be seen histologically in UC?
massive influx of inflammatory cells
basal lymphoplasmacytic infiltrate with irregular shaped branching crypts
crypt abscesses
severe ulceration with fibrinopurulent exudate
what would be the consequences if medical therapy were to fail in UC?
subtotal colectomy
are pseudopolyps seen in UC?
yes
not always but often
UC gives transmural inflammation, true or false?
false
inflammation confined to mucosa/submucosa
does UC give granulomas?
no
does UC give chronic active colitis?
yes
- cryptitis
- crypt abscesses
what are the complications of UC?
intractable disease - due to intercurrent enteric bacteria infection toxic megacolon colorectal carcinoma blood loss electrolyte disturbance (hypokalaemia) anal fissures (not common)
what is toxic megacolon?
acute or acute on chronic fulminant colitis
colon swells up to huge size
will rupture unless removed = emergency colectomy
what extra GI manifestations can UC cause?
eyes - uveitis
liver - primary sclerosing cholangitis
joints - arthritis, ank spondylitis
skin - pyoderma gangrenosum, erythema nodusum
where is UC incidence high/low?
high in north America,Europe, Scotland
low in Africa, South America, Asia
is there a genetic link in UC?
possibly
high concordance in monozygotic twins
association with HLA-DR2
familial cases assoc with NOD-2 gene
describe the aberrant immune response in UC
persistent activation of T cells and macrophages
autoantibodies present (eg ANCA)
excess pro-inflammatory cytokine production
maybe alterable by changing gut microflora
