Lecture 20 Alimentary Tract Pathology Flashcards
Small bowel and large bowel peristalsis is mediated by what neural control
Intrinsic (myenteric plexus) and extrinsic (autonomic innervation) neural control
Where is the Meissener’s plexus located
Base of submucosa
Where is the Auerbach plexus located
Between the inner circular and outer longitudinal layers of the muscular propria
Whats the main difference between ulcerative colitis and Crohn’s
Crohn’s can affect any part of the GIT from mouth the anus
UC is limited to colon
What is the aetiology of IBD
• Strong immune response against normal flora with defects in the epithelial barrier function in genetically susceptible individuals
What gene mutation is seen in Crohn’s disease
NOD2
What gene mutation is seen in Ulcerative colitis
HLA
What is UC called when it is localised in the rectum
Proctitis
Describe the pathology of UC
- Large bowel only
- Continuous pattern of inflammation.
- Rectum to proximal
- Pseudopolyps
- Ulceration
- Serosal surface minimal or no inflammation
Histology of UC
Inflamed mucosa Cryptitis Crypt abscesses Disarray of crypts Mucosal atrophy Ulceration into submucosa No granulomas Submucosal fibrosis Reactive atypic/dysplasia
Complications of UC
Haemorrhage
Perforation
Toxic dilatation
Describe pathology of Crohn’s disease
Granular serosa Mesentery thickened, oedema and fibrotic Narrowing of lumen Skip lesions Ulceration- cobble stone
Describe the histology of Crohn’s 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
Long term features of CD
- SI – malabsorption
- Strictures
- Fistulas and abscesses
- Perforation
- Increased risk of cancer
What is Ischaemic Enteritis
Occlusion of SI or LI major soppy vessels
Predisposing Conditions for Ischaemia
Arterial thrombosis
Arterial embolism
Non-occlusive ischaemia
Histology of 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
Features of Chronic ischaemia
- Mucosal inflammation
- Ulceration
- Submucosal inflammation
- Fibrosis
- Stricture
Define Radiation Colitis
• Abdominal irradiation can impair the normal proliferative activity of the small and large bowel epithelium
Symptoms of radiation colitis
Anorexia, abdominal cramps, diarrhoea and malabsorption
Histology of radiation colitis
- Bizarre cellular changes
- Inflammation-crypt abscesses and eosinophils
- Later-arterial stenosis
- Ulceration
- Necrosis
- Haemorrhage
- perforation
Causes of appendicitis
Obstruction
Enterobius vermicularis
Intraluminal pressure leading to ischaemia
Histology of appendicitis
Macro-fibrinopurulent exudate, perforation, abscess
• Acute suppurative inflammation in wall and pus in lumen
• Acute gangrenous-full thickness necrosis +/- perforation
Colorectal adenocarcinoma right sided
exophytic/polypoid Anaemia- altered blood pH Vague pain Weakness Obstruction
Colorectal adenocarcinoma left sided
Annular- napkin ring lesion
Bleeding- fresh altered blood PR
Altered bowel habit
Obstruction
