Alimentary Tract Pathology Flashcards
What are the three cell types in the small intestine?
Goblet Cells
Columnar absorptive cells
Endocrine cells
Where is Meissener’s Plexus and Auerbach Plexus
Meissener’s Plexus = base of the sub mucosa
Auerbach Plexus = between the inner circular and the outer longitudinal layers of the muscularis propria
What gene mutation is associated with CD?
NOD2
What gene mutation is associated with UC?
HLA
Whats the basic suspected cause of IBD?
Strong immune response against normal flora with defects in the epithelial barrier function in genetically susceptible individuals.
What antibody can you use in diagnosis of IBD?
What is its limitations?
perinuclear AntiNeutrophilic Cytoplasmic Antibody (pANCA)
Positive in 75% of UC patients
BUT only 11% of CD patients
NOT diagnostic
Can the appendix be involved in Ulcerative Colitis?
Yes
What is the definitive histological difference between UC and CD
UC = No granulomas CD = granulomas
What are strictures in UC compared to Crohn’s?
CD = Variable UC = late/rare
How do pseudopolyps and ulcers in CD and UC compare?
Pseudopolyps are marked in both UC and CD
Ulcers in CD are deep and linear
Ulcers in UC are superficial
How does the fibrosis in CD compare to UC?
Moderate in CD
Mild in UC
Concerning ischaemic enteritis, how do acute and gradual occlusion compare?
Acute of 1 of the 3 major supply vessels leads to infarction.
Gradual occlusion can have little effect- anastomotic circulation
What areas are at risk from acute ischaemia?
Splenic flexure and sigmoid
Watershed areas
What is the histology of acute ischaemia?
Oedema
Interstitial haemorrhage
Sloughing necrosis of mucosa (ghost outlines)
Nuclei indistinct
Initial absence of inflammation
1-4 days = bacteria -> gangrene and perforation
Vascular dilatation
What are the features of Chronic ischaemia?
Mucosal inflammation Ulceration Submucosal inflammation Fibrosis Stricture
Explain radiation colitis
Abdominal irradiation can impair the normal proliferative activity of the small and large bowel epithelium
Usually rectum-pelvic radiotherapy
Damage depends on dose
Targets actively dividing cells (esp. blood vessels and crypt epithelium)
What are the symptoms of radiation colitis?
Anorexia, abdominal cramps, diarrhoea and malabsoption
Chronic disease will mimic IBD
What is the histology of radiation colitis?
Bizarre cellular changes Inflammation = crypt abscesses and eosinophils Later = Arterial stenosis Ulceration Necrosis Haemorrhage Perforation
What happens to the appendix as we age?
Prominent lymphoid tissue regresses with age
Fibrous obliteration
What organisms may obstruct the appendix and what can this cause?
Feocolith or Enterobius Vermicularis
Increased intraluminal pressure -> ischaemia
What is the macro and microscopic histology of appendicitis?
Macroscopically:
Fibrinopurulent exudate, perforation, abscess
Microscopically:
Active suppurative inflammation in the wall and puss in the lumen
Acute gangrenous full thickness necrosis +/- perforation
What structures does dysplasia in the colon usually form?
Adenoma’s (polyps):
- Tubular (90% in colon)
- Villous
- Tubulovillous
50% are solitary
Prevelence = 30% at post mortem
Dysplasia in adenoma’s are divided into two.
What are the histological features of each?
Low Grade Dysplasia:
- Increased nuclear number
- Increased nuclear size
- Reduced Mucin
High Grade Dysplasia:
- Carcinoma in situ
- Crowded
- Very irregular
- Not yet invasive
What are the risk factors of colorectal carcinoma?
Lifestyle
Family
IBD (UC and CD)
Genetics: FAP, HNPCC, Peutz-Jeghers
What are the features of right sided adenocarcinoma of the colon?
Exophytic/polypoid Anaemia Vague pain weakness Obstuction
What are the features of left sided adenocarcinoma of the colon?
Annular (napkin ring lesions)
Bleeding (fresh/altered blood PR)
Altered bowel habit
Obstruction
