Pathology of colon Flashcards
GI tract: role in immunity
GI tract presents a large surface area for exposure to environmental antigens
what poses a threat to intestinal immune system
chronic disease
life threatening acute conditions
what is the small and large bowel peristalsis mediated by?
intrinsic (myenteric plexus) and extrinsic (autonomic innervation) neural control
what is another term for the myenteric plexus and where are they found
auerbach’s plexus
found between the inner circular and outer longitudinal layers of the muscularis propria
what is another term for the submucosal plexus and where are they found
meissener’s plexus
found at the base of the submucosa
types of inflammatory bowel disease? (5)
ulcerative colitis Crohn's disease ischaemic colitis radiation colitis appendicitis
how do they think ulcerative colitis or Chron’s disease come about?
chronic inflammatory conditions resulting from inappropriate immune response against the gut flora in a genetically susceptible person
what are the 2 main types of idiopathic inflammatory bowel disease?
Crohn’s disease
ulcerative colitis
what part of the GI tract does Chron’s affect?
it can affect any part of the GI tract from mouth to anus
where does ulcerative colitis affect
only the colon
name the gene associated with Chron’s disease
NOD2 gene
name the gene associated with ulcerative colitis
HLA gene
how is inflammatory bowel disease diagnosed?
clinical history
radiographic examination
pathological correlation
pANCA antibodies = positive in 75% UC patients but only 11% CD patients
in children it is harder to tell the diagnosis but as you grow older the phenotype becomes clearer - tends to be uc>cd
what does pANCA stand for
perinuclear antineutrophilic cytoplasmic antibody
Ulcerative colitis general info: what is it? prevalence etc
relapsing and remitting inflammatory disorder of the colonic mucosa
it never spreads back into the ileum (except for backwash ileitis)
M=F
only affects the colon but it can be localised to the rectum. The appendix can be involved sometimes
10% get pancolitis (whole large intestine + rectum and this may or may not involve the distal part of the ileum too
more commonly spreads proximally
Pathology of ulcerative colitis (6)
Large intestine and rectum only
Continuous pattern of inflammation
Rectum to proximal
Pseudopolyps
Ulceration
Serosal surface minimal or no inflammation
what might you see in the histology of colon with ulcerative colitis
Mucosa inflammation
Cryptitis
Crypt abscesses
NO granulomas
what is the risk of having pancolitis for over 10 years? (4)
could develop cancer
haemmorrhage
perforation
toxic dilatation
ulcerative colitis causes reactive atypia - what does this mean?
results in changes due to inflammation or injury without neoplastic change
Describe what Chron’s disease is? (5 points)
an IBD - characterised by transmural granulomatous inflammation - same cause as ulcerative colitis
Anywhere from mouth - anus
40% Small intestine
30% SI and LI
30% colon
systemic manifestations
more common in females
more common in caucasians or Jewish population
what does chron’s disease do to nearby structures/tissues in the GI tract?
mesentery thickens and becomes oedematous and fibrotic
thick wall
narrowing of the lumen
ulceration that looks like cobblestones
what does the term ‘skip lesions’ refer to and which disease is it linked with
in chron’s disease there are parts of unaffected bowel between areas of active disease - this is not the case with uc
What types of things would you expect to see in the histology of chron’s disease? (8)
Cryptitis and crypt abscesses
Architectural distortion
Atrophy –crypt destruction
Ulceration-deep
Transmural inflammation
Chain of pearls - gas bubbles - bowel destruction
Non-caseating granulomas
Fibrosis
Long term features of chron’s disease? (5)
small intestine malabsorption
strictures - narrowing
fistulas (abnormal collection) and abscesses
perforation
increased risk of cancer - 5 x
3 types of Ischaemia of the bowel
acute mesenteric ischaemia
chronic mesenteric ischaemia
chronic colonic ischaemia
where can ischaemic lesions affect the bowel?
restricted to either the small intestine or large intestine or can affect both depending on the vessel affected
a gradual occlusion can have little effect due to anastomotic circulations
what are the 3 major supply vessels
coeliac artery
inferor mesenteric artery
superior mesenteric artery
a major vessel occlusion can cause what?
transmural injury
acute/chronic hypoperfusion - mucosal and/or submmucosal injury
predisposing conditions for ischaemia (3)
arterial thrombosis - severe atherosclerosis, dissecting anuerysm
arterial embolism - cardiac vegetations, acute atheroembolism
non-occlusive ischaemia - cardiac failure, shock/dehydration
Chronic ischaemia can be caused by what (5)
Mucosal inflammation Ulceration Submucosal inflammation Fibrosis Stricture
what is radiation colitis
inflammation of your small and/or large intestine from radiation treatments in your stomach, sexual organs, or rectum (pelvic radiotherapy)
can damage cells, tissues, epithelium activity
radiation targets actively dividing cells esp blood vessels and crypt epithelium
dysplasia in the large bowel can be of two types
low grade
high grade
define dysplasia
the presence of cells of an abnormal type within a tissue, which may signify a stage preceding the development of cancer
dysplasia: polyps can be of 3 types
tubular (90% occur in colon)
villous
tubulovillous
these adenomas can turn into cancerous ones
50% are solitary = benign
Histological characteristics of low grade dysplasia
increased nuclear size and numbers
reduced mucin
Histological characteristics of high grade dysplasia
carcinoma in situ
crowded
very irregular
not yet invasive
Risk factors for colorectal carcinoma (4)
lifestyle
family history
IBD - UC and Chron’s
genetics - Familial adenomatous polyposis (FAP), Hereditary nonpolyposis colorectal cancer (HNPCC), Peutz-Jeghers syndrome - develop benign polyps
Symptoms of right sided colorectal adenocarcinoma (ascending colon and caecum)
anaemia - altered blood pressure
vague pain
weakness
weight loss
Symptoms of left sided colorectal adenocarcinoma (descending colon, sigmoid colon and rectum)
annular - napkin ring lesion
bleeding - fresh/ altered blood pressure
altered bowel habit or obstruction
how common is colorectal cancer?
3rd m ost common cancer and 2nd most common cause of UK cancer deaths
usually presents in >60 year olds
