Pathology- Large Intestine Flashcards
what is psuedomembranous colitis
antibiotic induced colitis
what can a blocked and inflamed diverticulae cause
abscesses, fibrosis, strictures, adhesions
what are the symptoms of diverticular disease
often symptomatic, symptoms only if complicated
what is the difference between a true and a false diverticulum
True diverticula involve all layers of the structure, including muscularis propria and adventitia, such as Meckel’s diverticulum.
False diverticula (also known as “pseudodiverticula”) do not involve muscular layers or adventitia. False diverticula, in the GI tract for instance, involve only the submucosa and mucosa.
what is diverticular disease of the large bowel associated with
low fibre diet and increased intralumenal pressure (compacts stools)
what are the complications of diverticular disease of the large bowel
inflammation, rupture, abscess (can erode into artery), fistula, massive bleeding
is merkels diverticulum true or false
true
what does ischaemia of the large bowel look like microscopically
destruction of colonic mucosae- withering of crypts and smudging of lamina propria
pink smudgy lamina propria
fewer chronic inflammatory cells
what can cause ischaemia of the large bowel
CVS disease- atherosclerosis of mesenteric vessels
A Fib- shock, as blood supply prioritised
Embolus- Vasculitis
what does the SMA supply in the gut
small bowel and proximal colon
what does the IMA supply in the gut
the large intestine
what is the most metabolically active part of the bowel
the mucosa
what is the usual clinical context of ischaemic colitis
elderly people, left sided, segmental on endoscopy
what are the complications of ischaemic colitis
massive bleeding, rupture, stricture
where is a speckeled colonic lining seen
antibiotic induced ‘pseudomembranous’ colitis
what does pseudomembranous colitis look like endoscopically
patchy yellow membranous exudate on mucosal surface
what does antibiotic induce colitis look like microscopically
explosive fibrinopurulent exudate on surface, explosive lesions of mucosa- volcano, crypts dead, everything inside crytps and blood make plaques on top of damaged epithelium
who gets pseudomembranous colitis
patients on broad spectrum antibiotics
what causes antibiotic induced colitis
C diff overgrowthm toxins A and B attack endothelium and epithelium
what are the symptoms of antibiotic induced colitis
massive diarrhoea and bleeding- could be fatal
how is antibiotic induced colitis treated
flagyl/vancomycin , may need colectomy
what causes watery diarrhoea, a patchy thickened basement membrane, normal endoscopy, no chronic architectural changes,
collagenous colitis
what is collagenous colitis
autoimmune disease of the colon of unknown aetiology
what causes the diarrhoea in collagenous colitis
thick band of collagen beneath epithelial cells- increase in sub epithelial collagen
what inflammatory cells are associated with collagenous colitis
intraepithelial inflammatory cells
what causes watery diarrhoea, normal mucosa and crypt architecture, a massive increase in intra-epithelial lymphocytes
lymphocytic colitis
what causes the diarrhoea in lymphocytic colitis
the presence of lymphocytes creates defects in epithelial barrier
what is telangectasia
a condition in which widened venules (tiny blood vessels) cause threadlike red lines or patterns on the skin
what is seen microscopically in radiation colitis
Bizarre stromal cells, bizzarre vessels, pinpoint haemorrhages in rectum, Random distribution
Vascular spaces- expanded capillaries
how does radiotherapy kill cancer
one way is to kill blood vessels supplying the tumour
what can cause general inflammation of the colon, a busy epithelium with crypt regularity, B cells moving into lumen in florid diffuce acute cryptitis, focal acute cryptitis as neutrophils try to get into colonic crypts to get to bacteria
acute infective colitis
what usually causes acute colitis
infection- rarely drugs, ischaemia, endoscopy prep
