Pathology of Colon Flashcards
What bowel has the presence of innumerable villi
Small intestine
What are the cryptic and cells present in the large intestine
Tubular crypts
Surface-columnar absorptive cells
Crypts -goblet cells
endocrine cells
How often is the stem cell turnover in the large intestine
3-8days
What is the neural control of the small and large intestine
Both the small and large bowel peristalsis is mediated by intrinsic (myenteric plexus) and extrinsic (autonomic innervation)
What are the two myenteric plexus and where are they located
Meissener’s plexus: base of the submucosa
Auerbach plexus: between the inner circular and outer longitudinal layers of the muscularis propria
What is the definition of 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
What are the two main and other diseases of IBD
Crohns disease
Ulcerative disease
also
- ischaemic colitis
- radiation colitis
- Appendicitis
What is the differences between Crohns disease and ulcerative colitis
CD - affect any part of the GI tract where UC is limited to the colon
An NOD2 gee mutation is associated with what IBD condition
Crohns disease
HLA is associated with what IBD condition
Ulcerative colitis
What is the pathology of IBD
Strong exaggerated immune response against normal flora due to a defects in the epithelial barrier function allowing microbes access to muscle lymphoid tissue
What is required for the diagnosis
Clinical history Radiographic examination Pathological correlation pANCA (perinuclear antineutrophilic cytoplasmic antibody)
What is the presentation go Ulcerative colitis
Can be localised to the rectum (proctitis)
More commonly spreads proximally
10% Pancolitis, +/- “backwash ileitis”
Appendix can be involved
Association with systemic manifestations
What is the pathology of UC
A continous pattern of inflammation in the large bowel only starting rectum to proximal
Results in
Pseudopolyps
Ulceration
Minimal or no inflammation on serosal surface
Where is UC mostly limited to histologically
Mucosa and submuscia
What happens to the mucosa in UC
Inflammation causing Cryptitis Crypt abscesses Mucosal atrophy
What happens to the submucosa in UC
Ulceration resulting in pseuodopolyps
submucosal fibrosis
What is the complications of UC
Dysplasia can occur increasing risk of cancer if adenomatous change
Haemorrhage
Perforation
Toxic dilatation
What do crohns and UC both have in common
Both have systemic manifestation
What is the pathology of crohns disease
= Granular serosa
Wrapping of mesenteric fat means
- Mesentry
= thickened, oedematous and fibrotic - Wall
= thick and oedematous
so overall narrowing of the lumen occurs
Resulting in Sharp demarcation of disease segments from adjacent normal tissue “skip
lesions”
Ulceration- “cobblestone”
What is present in the histology of crohns disease
Cryptitis and crypt abscesses
Architectural distortion
Atrophy –crypt destruction
Ulceration-deep
Transmural inflammation
(Chain of pearls)
Non-caseating granulomas
Fibrosis
Lymphangiectasia
Hypertrophy of mural nerves
Paneth cell metaplasia
What IBD disease has granulomas present
Crohns
What is the complications of CD
Small intestine malabsorbtion
Strictures
Fistulas
Abscesses
Perforation
Increased risk of cancer.
How does ischeamic enteritis occur
Acute occlusion of 1 of the 3 major supply vessels leads to infarction - (Coeliac, Inferior and Superior mesenteric arteries)
Leading to hypo perfusion injuring mucosal and/or submucosal
Is either acute or chronic
What happens in gradual occlusion of major BV supply of bowels
Little effect
anastomotic circulation
What kind of injury is iscaemic enteritis causing major vessel occlusion
Transmural injury to mucosal +/- submucosa
What is the predisposing conditions for ischaemia
Arterial thrombosis
Arterial embolism
Non-occlusiove ischemia
eg cardiac failure, vasoconstrictive drugs/shock
What is the pathology of acute ischaemia
Splenic flexure vulnerable
Early-intense congestion
dusky/purple/blue
Lumen – sanguinous mucin
Arterial sharp demarcation
Venous fade gradually
What is the histology go acute ischaemia
Oedema
Interstitial haemorrhages
Sloughing necrosis of mucosa-ghost outlines
Nuclei indistinct
Initial absence of inflammation
1-4 days –bacteria-gangrene and perforation
Vascular dilatation
What is the pathology of chronic ischaemia
Mucosal inflammation
Ulceration
Submucosal inflammation
Fibrosis
Stricture
What is likely aetiology of radiation colitis
Rectum-pelvic radiotherapy impairing the normal proliferative activity of the bowels
What is damaged in radiation colitis and what does the damage depend on
Actively dividing cells esp. blood vessels
and crypt epithelium are all targeted for damage which is dependant on the dose of radiotherapy
What is the symptoms of radiation colitis
Anorexia
Abdominal cramps
Diarrhoea
Malabsorption
What is the histology of radiation colitis
Bizarre cellular changes
Inflammation-crypt abscesses and eosinophils
What is the complications of radiation colitis
Later-arterial stenosis Ulceration Necrosis Haemorrhage perforation
What prominent lymphoid tissue regresses with age
Bowel remnant - Appendice (6-7cm)
What is the pathology of appendicitis
Fibrous obliteration causing acute inflammation
What is the aetiology of appendicitis
Obstruction of appendix
(eg enterobius vermicularis - worms in lumen)
or
Increased intraluminal pressure causing ischaemia
What is seen in the histology of appendicitis
Macro
- fibrinopurulent exudate, perforation, abscess
Micro
-Acute suppurative inflammation in wall and pus in lumen
-Acute gangrenous-full thickness necrosis +/- perforation
What are the 3 adenoma/polyps found in the colon
Tubular
Villous Tubulovillous
What happens in low grade dysplasia in adenomas of the colon
Increased nuclear nos.
Increased
nuclear size
Reduced mucin
What happens in high grade dysplasia of adenomas of the colon
Carcinoma in situ
Crowded/Very irregular
Not yet invasive
What are the risk factors of colorectal cancer
Lifestyle
Family History
IBD
Genetics
What are the genetic genes increasing the risk of colorectal cancer
FAP
HNPCC
Peutz-Jeghers
What kind of cancer is the majority of colorectal cancers
98% are adenocarcinomas
What is the more specific symptoms of right sided colorectal adenocarcinoma
Anaemia
Vague pain
Weakness
Obstruction
What is the appearance of right sided colorectal adenocarcinoma
Polypoid
What is the appearance of left sided colorectal adenocarcinoma
Annular = napkin ring lesion
What are the specific symptoms of left sided colorectal adenocarcinoma
Bleeding
Altered bowel habit
Obstruction
What is the carrying large bowel neoplasia
Low - high grade dysplasia
to
Malignancy
