Pathology of the large bowel Flashcards
What is the histopathological appearance of diverticulae?
Look like the normal large bowel. It is a neuromuscular mechanical process rather then a neoplastic process.
Why does a diet low in fibre cause diverticular disease?
Fibre makes the stool bulky. Bulky stool is easier to move by peristalsis. Watery stool means the intraluminal prssure must be higher to move the stool and this increase intraluminal pressure causes the mucosa of the colon to hurniate forming flase diverticulae
Diverticular disease is common and often assymtomatic. T of F?
True
What are th complications of diverticular disease?
Inflammation- diverticulitis Rupture Abscess Fistula Haemorrhage as the arterys are in the same mesentery as the abscess
What is the gross pathological appearance of ischemia of the large bowel?
Redness
What are the histopathological features of ischemia in the large bowel?
Crypts dying- withering crypts. Pink smudgy lamina propria Fewer chronic inflammatory cells Destruction of the colonic mucosa- this is the most biologically active and will die first in ischemia. Necrosis spreads from the inside of the vessel outwards. Necrotic tissue- red is dead.
Which patient groups are more likely to suffer from ischemia of the bowel, what is the cause and where is this most likely to occur?
Elderly. Anyone with a history of CVD (atherosclerosis of mesenteric vessels), AF (embolism), Haemorrhagic shock (blood supply to bowel is diverted), Vasculitis.
Most likely Left sided- splenic flexure affecting the inferior mesenteric artery
What are the complications of ischemic colitis?
Haemorrhage
Rupture (full thickness necrosis)
Stricture
What are the gross pathological findings of pseudomembranous colitis?
Patchy yellow membranous exudate on mucosal surfaces. Yellow spots
What are the histopathological findings of pseudomembranous colitis?
Plaque tightly adhered to the epithilial membrance (pseudomembranous) with fibropurulent exudate on surface.
Explosive lesions on the mucosa
What causes pseudomembranous colitis?
C difficle infection due to course of broard spectrum antibiotics.
Toxin A and B produced by C diss attack the epithilium and cause sections to die and ‘explode’
What are the symptoms of pseudomembraous colitis?
Diarrhoea and bleeding
How is pseudomembranous colitis treated?
Vancomycin but may need a colectomy and can be fatal
What is the likely diagnosis in a female patient in 50s/60s with a history of autoimmune disease who has watery diarrhoea and is going to the batroom over 20 times a day?
Collagenous colitis- iodiopathic disease.
What is the gross pathological finding of collagenous colitis?
Normal mucosa
What is the histopathological finding of collagenous colitis?
Thick band of collagen beneath the epithilital cells causing a thickened basement membrane. Disease is patchy and associated with intraepithilial inflammatory cells
What may cause collageous colitis?
Drugs NSAIDs, lansoprazole.
What are the gross pathological changes of lymphocytic colitis?
Normal mucosa
What are the histopathological changes of lymphocytic colitis?
Increase in intra-epithilial lymphocytes in the epithilial membrane. No chronic changes to crypts. No thickening of basement membrane.
What is lymphocytic colitis associated with in young people?
Coelliac disease
What is microscopic colitis?
Cases with mixed features of collagenous colitis and lymphocytic colitis. No relationship to IBD. Patients have a normal endoscopy
What are the features of radiation colitis in the patient history?
Previously treated for cancer of the prostate, uterus, cervix or bladder. => Previous radiotherapy
How does radiotherapy effect the vasculature?
Its toxic to endothilial cells
Where is radiation colitis most commonly found?
In the rectum as this is near the organs which had cancer and were treated with radiotherapy
What are the histopathological findings of radiation colitis?
Branched crypts
Lamina propria with expanded capillary spaces.
Pin point haemorraheges on endoscopy- telangiectasia
What is the gross pathology of infective colitis?
Generalised red , inflamed, oedema.
What is the histopathology of infective colitis?
No crypt irregularity.
Neutrophils moving to the umen of crypts as that is where bacteria are found. Acute inflammation in bowel wall
Acute colitis is normally caused by infection. What are the other causes?
Drugs, ischemia, endoscopy prep.
Can occasionally be the onset of IBD- follow up screening if continued
