Pathology of the colon Flashcards
What is the structure of the colon, from proximal to distal?
Caecum Ascending colon Transverse colon Descending colon Sigmoid colon Rectum
What is the peritoneum of the colon?
Caecum- inta A- retro T- intra D- retro S- intra
What is the histology of the colon?
Flat
Tubular crypts
-goblet and endocrine cells
Columnar absorptive epithelium
What is idiopathic IBD?
Chronic inflammatory conditions resulting from inappropriate and persistent activation of mucosal immune system
What are the 2 main inflammatory bowel diseases?
Crohn’s
Ulcerative colitis
What is the main difference between Crohn’s and UC?
Crohn’s can affect anywhere from mouth to anus
UC can only affect colon
What is the cause of IBD?
Strong immune response against normal flora with defects in epithelial barrier function in genetically suseptibel individuals
How is IBD diagnosed?
History, x ray, pathological correlation
pANCA- good for differentiating UC and Crohn’s
Who does UC most commonly affect?
Males
20-30 and 70-80 years
How does UC spread?
Most commonly proximally
What is the pathology of UC?
Large intestine only Continuous pattern of inflammation Often spreads from rectum proximally Pseudopolyps UlcerationSerosal surface has minimal or no inflammation
What is the histology of UC?
Inflammation of mucosa Crypitis Crypt abscesses and disarray Mucosal atrophy Ulceration into submucosa creating pseudopolyps Submucosal fibrosis No granulomas
What can submucosal fibrosis is UC cause?
Stricturing of bowel and obstruction
What are the complications of UC?
Haemorrhage
Perforation
Toxic dilation
Where does the majority of Crohn’s affect?
Small intestine
What % of Crohn’s affects the small intestine and large intestine?
Small- 40%
Both- 30%
Large- 30%
What is the pathology of Crohn’s?
Granular serosa Wrapping mesenteric fat Thickened, oedematous, fibrotic mesentery and wall Narrowing of lumen Ulceration Patch disease
What is the histology of Crohn’s disease?
Cryptitis and crypt abscesses Architestural distortion Atrophy Deep ulceration Transmural inflammation Non caveating granulomas Fibrosis Lymphangiectasia Hypertrophy of mural nerves Paneth cell metaplasia
What are the long term features of Crohn’s?
Malabsorption Strictures Fistulas and abscesses Perforation Increased risk of cancer
What is ischaemic enteritis?
Occlusion of celiac, s mesenteric or i mesenteric vessels causing infarction
What does major vessel occlusion in ischaemic enteritis cause?
Transmural injury
What are the predisposing conditions for arterial thrombosis in ischaemic enteritis?
Severe atherosclerosis Systemic vasculitis Dissecting aneurysm Hypercoagulate states Oral contraceptive
What are the predisposing conditions for arterial embolism in ischaemic enteritis?
Cardiac vegetations
Acute after-embolism
Cholesterol embolism
What are the predisposing conditions for non occlusive ischaemic enteritis?
Cardiac failure
Shock/dehydration
Vasoconstrictive drugs
What part of the gut is vulnerable to acute ischaemic enteritis?
Splenic flexure
What is the histology of acute ischaemic enteritis?
Oedema Interstitial haemorrhages Sloughing necrosis of mucosa Nuclei indistinct Initial absence of inflammation Vascular dilatation
What are the features of chronic ischaemic enteritis?
Mucosal inflammation Ulceration Submucosal inflammation Fibrosis Stricture
Where does radiation colitis normally affect?
Rectum after pelvic radiotherapy
What does radiation colitis normally target?
Actively dividing cells, esp blood vessels and crypt epithelium
what are the symptoms of radiation colitis?
Anorexia
Abdo cramps
Diarrhoea
Malabsorption
What is the histology of radiation colitis?
Inflammation Arterial stenosis Ulceration Necrosis Haemorrhage Perforation
What is the histology of appendicitis?
Fibrinopurulent exudate
Perforation
Abscess
Acute inflammaation in wall, pus in lumen
Acute gangrenous full thickness necrosis, w/ possible perforation
What are the forms of colorectal dysplasia?
Tubular, villous or tubulovillous adenomas
What are the features of low grade colorectal dysplasia?
Increased nuclear number and size
Reduced mucin
What are the features of high grade colorectal dysplasia?
Carcinoma in situ
Crowded
Very irregular
Not yet invasive
What are the majority of colorectal cancers?
Adenocarcinomas
What are the risk factors of colorectal cancer?
Lifestyle
Family history
IBD
Genetics
What are the signs and symptoms of right sided adenocarcinoma of the colon?
Anaemia
Vague pain
Weakness
Obstruction
What are the signs and symptoms of left sided adenocarcinoma of the colon?
Fresh blood PR
Altered bowel habit
Obstruction
