Alimentary tract pathology Flashcards
What are the notes of mention for the hiistology of the small bowel?
The mucosa has innumerable villi
There are goblet cells, columnar absorbitive cells and endocrine cells
Also crypts have 4 cell types - stem, goblet, paneth, endocrine
What cell types are found in the crypts within the large bowel?
goblet, endocrine and stem
What are the chronic and acute causes for dysfunction of the GI tract immune system?
chronic disease and acute life threatening conditions including ecoli and salmonella
How is peristalsis mediated?
intinsic - myenteric plexus and extrinsic by the autonomic nervous system
What is 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
Where can crohns disease effect in the GI tract?
any part from mouth to anus
Where can ulcerative coltits effect in the GI tract?
the large bowel
What are the genes linked in genetics to crohn’s disease and ulcerative colitis?
NOD2
HLA
What is the antibody pANCA role in inflammatory bowel disease?
75%+ in ulcerative colitis but only 11% in crohn’s disease
What is the epidemiology of ulcerative colitis?
Male=female, peaks at 20-30 and 70-80 years old
What is proctitis?
ulcerative colitis limited to the rectum
What is pancolitis?
ulcerative colitis spanning the entire colon
What is backwash ileitis?
ulcerative colitis with inflammation seen in the distal ileum
How does ulcerative colitis spread?
rectum –> proximal
Does crohns or ulcerative colitis have granulomas?
crohns - non caseating
Does crohns or ulcerative colitis have skip lesions with a patchy distribution?
crohn’s
Explain the epidemiology of crohn’s disease
female predominant, effects anywhere from mouth to anus and also have peaks at ages 20-30 and 60-70 with the majority being found in the small intestine
What are the long term features of crohn’s disease?
increased cancer risk
malabsorption
strictures, fistulas, abscesses and perforation
What can acute occlusion of one of the 3 main vessels of the gut lead to?
infarction - can lose part of the bowel
What are predisposing conditions for ischaemic enteritis?
arterial thrombosis eg oral contraceptives, atherosclerosis
arterial embolism and non occlusive ischaemia eg shock and dehydration
Where is particular;y vulnerable in acute ischaemia?
splenic flexure
Explain the difference between arterial and venous appearance in acute ischaemia?
arterial is sharp whereas venous is a gradual fade
What can ischaemia lead to?
necrosis and gangrene accompanied by oedema and indistinct nuclei
What can chronic ischaemia lead to?
ulceration, fibrosis and stricture
What parts of the gut tube histologically are effected in chronic ischaemia by inflammation?
mucosa and submucosa
What is radiation colitis?
abdominal irradiation impairing the normal proliferative activity of the small and large bowel epithelium, usually with rectum-pelvic radiotherapy targeting blood vessels and crypts
symptoms of radiation colitis?
anorexia, abdominal cramps, diarrhoea and malabsorption
What are the 2 knock-on effects of acute inflammation of the appendix?
obstruction
increased intraluminal pressure - ischaemia
What is seen both macroscopically and microscopically in appendicitis?
exudate, perforation and abscess
inflammation, necrosis and gangrene
What are the 2 grades of large bowel dysplasia and differentiate them
low - increased nuclear size and number with reduced mucin
high - carcinoma in situ, crowded and irregular
What are the 3 types of adenoma in large bowel dysplasia?
tubular
villous
tubulovillous
what are the majority of carcinoma in the large bowel cell type?
adenocarcinoma usually of pre-existing polyps
What are risk factors for adenocarcinoma of the large bowel?
lifestyle
family history
genetics eg FAP, HNPCC
IBD
Symptoms of right and left sided bowel neoplasia?
right = anaemia, vague pain, weakness left = blood from rectum, altered bowel habit
What are the 2 scales used to stage large bowel cancer for prognosis?
TNM
Dukes - A,B,C1,C2
