Pathology of Colon Flashcards
name the three cell types in the small bowel
> goblet cells
columnar absorptive cells
endocrine cells
what cells are at the surface of the large bowel?
columnar absorptive cells
what cells are present in the crypts of the large bowel?
> goblet cells
endocrine cells
stem cells
what is large and small bowel peristalsis mediated by?
> intrinsic - enteric nervous system
> extrinsic - autonomic innervation
what makes up the enteric nervous system?
> meissener’s plexus: base of the submucosa (submucosal plexus)
auerbach plexus: between the inner circular and outer longitudinal layers of the muscularis propria (myenteric plexus)
what conditions are included within inflammatory bowel disease?
> ulcerative colitis > crohn's disease > ischaemic colitis > radiation colitis > appendicitis
define idiopathic inflammatory bowel disease?
chronic inflammatory conditions resulting from inappropriate and persistent activation of the mucosal immune system driven by the presence of normal intraluminal flora
what do you require to diagnose IBD?
> clinical history
radiographic examination
pathological correlation
what does ulcerative colitis effect?
the large bowel
what would you expect to see in histology of ulcerative colitis?
> inflammation of mucosa > cryptitis > crypt abscesses > architectural disarray of crypts > ulceration into submucosa (psuedopolyps) > submucosal fibrosis
what are the possible complications from ulcerative colitis?
> dysplasia
haemorrhage
perforation
toxic dilatation
describe the pathology of crohns disease
> granular serosa
mesentery is thickened, oedematous and fibrotic
lumen is narrowed
‘skip lesions’ demarcated areas of disease, adjacent to normal tissue
ulceration - cobblestone appearance
what would you expect to see in a histological slide of crohns disease?
> non-caseating granulomas > cryptitis and crypt abscesses > atrophy - crypt destruction > deep ulceration > transmural inflammation > fibrosis > lymphangiectasia > hypertrophy of mural nerves > paneth cell metaplasia
what are the long term features of crohns disease?
> malabsorption > strictures > fistulas and abscesses > perforation > increased cancer risk (5*)
in ischaemic enteritis what can lead to infarction?
acute occlusion of 1 of the 3 major supply vessels
why may gradual occlusion have little effect in ischaemic enteritis?
anastomotic circulation
what conditions can predispose for ischaemia?
> arterial thrombosis (atherosclerosis, OCP, dissecting aneurysm)
arterial embolism (cardiac vegetations, cholesterol embolism)
non-occlusive ischaemia (cardiac failure, shock, vasoconstrictive drugs)
describe the histology of acute ischaemia
> oedema > interstitial haemorrhage > sloughing necrosis of mucosa > nuclei indistinct > vascular dilatation > 1-4 days bacteria gangrene
what can abdominal irradiation impair?
the normal proliferative activity of the small and large bowel epithelium
what are the symptoms of radiation colitis?
> anorexia > abdominal cramps > diarrhoea > malabsorption > chronic mimics IBD
describe histological changes that can be seen in radiation colitis
> inflammation - crypt abscesses and eosinophils > arterial stenosis > ulceration > necrosis > haemorrhage > perforation
how does appendicitis lead to ischaemia?
there is increased intraluminal pressure
describe the histological changes that may be seen in appendicitis
> acute supprative inflammation in the wall
pus in the lumen
acute gangrenous fill thickness necrosis (perforation)
describe the histological appearance of low grade adenoma dysplasia
> increased nuclear nos.
increased nuclear size
reduced mucin
describe the histological appearance of high grade adenoma dysplasia
> carcinoma in situ
crowded
very irregular
what are the risk factors for colorectal carcinomas?
> lifestyle
family history
genetics
IBD
