Pathology of Colon Flashcards
What is peristalsis mediated by in both small and large bowels?
Intrinsic (myenteric plexus)
Extrinsic (autonomic innervation)
Where is Meissener’s plexus?
Base of the submucosa
Where is Auerbach plexus?
Between the inner circular and outer longitudinal layers of the muscularis propria
What is idiopathic inflammatory bowel disease?
Chronic inflammation from inappropriate + persistent activation of muscosal immune system by presence of normal intraluminal flora
What are the 2 main IBDs?
Crohn’s disease
Ulcerative colitis
What is the main difference between crohns and ulcerative colitis?
CD can affect any part of GIT
UC limited to colon
What is the cause of IBD?
Exaggerated immune response
15% have affected 1st degree relative
What gene mutation is associated with CD?
NOD2
What gene has associations in UC?
HLA
What is the role of intestinal flora in the cause of IBD?
Defects in mucosal barrier could allow microbes access to mucosal lymphoid tissue triggering immune response
What test is used in diagnosis of IBD?
pANCA
+ve in 75% of UC
+ve in 11% of CD
What is the effect of UC?
Inflammation
Rectum to proximal
Pseudopolyps and ulceration can occur
Serosal surface usually minimal or no inflammation
What is the main difference in histology between UC and CD?
UC = no granulomas CD = non-caseating granulomas
What are the complications of UC?
Flat epithelial atypia = adenomatous change = invasive cancer
Haemorrhage
Perforation
Toxic dilatation
What are the effects of CD?
Wrapping mesenteric fat Mesentery = thickened, oedematous, fibrotic Wall thick Narrow lumen Ulceration
What are the long term features of CD?
Malabsorption in the small intestine Strictures Fistulas/abscesses Perforation Increased risk of cancer
What is ischaemic enteritis?
When blood flow to the intestines are restricted
Acute occlusion of which vessels leads to infarction?
Coeliac artery
Inferior mesenteric artery
Superior mesenteric artery
What are predisposing conditions for ischaemia?
Arterial thrombosis
Arterial embolism
Non-occlusive ischaemia
What can be seen in histology of acute ischaemia?
Oedema
Interstitial haemorrhages
Sloughing necrosis
Vascular dilatation
What happens in chronic ischaemia?
Mucosal inflammation Ulceration Submucosal inflammation Fibrosis Stricture
What is radiation colitis?
Radiation damages the small/large bowel
Damage depends on dose
Radiation targets fast dividing cells which are also blood vessels and crypt epithelium
What are the symptoms of radiation colitis?
Anorexia Abdominal cramps Diarrhoea Malabsorption Chronic - mimics IBD
What are histological features in radiation colitis?
Inflammation - crypt abscesses and eosinophils Later-arterial stenosis Ulceration Necrosis Haemorrhage Perforation
What is appendicitis?
Acute inflammation of the appendix due to obstruction
What are the histological features of appendicitis?
Fibrinopurulent exudate Perforation Abscess Inflammation in wall Pus in lumen Acute gangrenous
What are the types of adenoma?
Tubular (90% in colon)
Villous
Tubulovillous
What are the risk factors of colorectal carcinoma?
Lifestyle
FH
IBD
Genetics (FAP, HNPCC, Peutz-Jeghers)
What are the features of right sided colorectal adenocarcinoma?
Exophytic/polypod Anaemia Vague pain Weakness Obstruction
What are the features of left sided colorectal adenocarcinoma?
Annular
Bleeding
Altered bowel habit
Obstruction
