Pathology of GI Tract Flashcards
What is the histological morphology of coeliac disease?
Villi atrophy
Increased intraepithelial lymphocytes
Crypt elongation
lamina propria inflammation
What are diverticula of the large bowel? What are the main types?
Blind ending out-pouchings of large bowel (protrusions of mucosa and submucosa)
Congenital or acquired*
Where do diverticulosis of the colon take place the most?
Sigmoid colon (rarely proximal)
What is diverticulosis associated with?
Low fibre diet
Older age
What is the pathogenesis of diverticulosis?
Increased intra-luminal pressure due to IRREGULAR PERISTALSIS and development of compartments through weak parts of colon wall
Where (weak points) do diverticula develop in the colon?
Where arteries penetrate mesenteric and antimescenteric tania coli
Age related changes in connective tissue
What are the acute complications of diverticula?
- Diverticulitis/abcess
- perforation - infects parietal cavity (peritonitis)
- Ulceration - haemorrhage
What are the chronic complications of diverticulosis?
Intestinal obstruction (stricture development)
Fistula
Diverticular colitis
What is colitis? How it is divided?
Inflammation of colon
Acute (days - weeks) or chronic (months to years)
Where does colitis usually occur? where else can it occur?
Usually confined to mucosa
But can be transmural (i.e. all) e.g. crohns or submucosa/muscular
What are the two types of chronic idiopathic inflammatory bowel diseases?
Ulcerative colitis* (more common)
Crohns disease
Who is effected by chronic idiopathic inflammatory bowel disease the most?
young adults
Are females/males more effected by ulcerative colitis/crohns disease
Crohns = female
UC = equal
What are the risk factors for chronic idiopathic inflammatory bowel disease?
Smoking (EXCEPT ulcerative colitis = protective)
Contraceptive pill
Family history
What are the main clinical presentations of ulcerative colitis?
Diarrhoea (with urgency) RECTAL BLEEDING* Weight loss/anorexia Abdominal pain Anaemia (if blood loss = severe)
What are the clinical complications of ulcerative colitis?
- Toxic megacolon and perforation (severe colitis - dilated transverse colon)
- haemorrhage
- Stricture (rare)
- carcinoma
What part of bowel does ulcerative colitis effect?
Limited to rectum and colon (CONTINUOUS DISEASE i.e. spreads upwards)
What layers does ulcerative colitis affect?
Mucosa (superficial) - crypt distortion
What is a distinctive histological feature of ulcerative colitis?
Crypt abcess - neutrophil in crypts
What part of GI tract does crowns disease effect?
All of GI tract - from mouth to anus
Mostly Ileocolic (terminal ileum)
What are the clinical features of crowns disease?
Diarrhoea (can be bloody) Palpable bowel Weight loss Loss of appetite Ulcers (ANYWHERE in GI!)
What is a distinctive feature of Crohns disease?
Granuloma (~60% though)
What are the clinical complications of crown’s disease?
Toxic megacolon Perforation FISTULAS STRICTURES Haemorrhage Carcinoma Short bowel syndrome - repeated resection
What are the macroscopic/microscopic features of Ulcerative colitis?
- Colon, terminal ileum, appendix
- CONTINUOUS lesions
- ALWAYS involves rectum
- Terminal ileum involved 10% of time
- red, granular mucosa - flat, undermining ulcers
- Mucosa involvement
- Anal lesions = 25%
- No granulomas
- Fistulas DONT occur
- Strictures rare
- Inflammatory polyps = common
What are the macro/microscopic features of crowns disease?
- All GI tract effected
- Rectum involved 50% time
- SKIP LESIONS
- Fistulas above 10%
- Strictures common
- Anal lesions = 75%
- Cobblestone lesions
- Sarcoid like granulomas
- Inflammatory polyps less common
- Transmural (all layers) inflammation
Developing colorectal cancer can occur with colitis. What are the risk factors for developing colorectal cancer with colitis?
- Duration of disease
- Early onset of disease
- Total/extensive colitis
- Family history of cancer
- Presence of dysplasia
What is a colorectal polyp?
Mucosal protrusion (bulge in bowel)
Can be solitary or multiple (polyposis)
What are the characteristics of hyperplastic polyps?
- common
- 1-5mm
- Often multiple
- Sigmoid colon/rectum
- small polyps - NO MALIGNANT potential; larger (over 10mm) have malignant potential
What are the two types of hamartomatous polyps?
Juvenile
Peutz-jeghers
What are the characteristics of juvenile polyps?
- 10-30mm
- Spherical and pedunculated
- rectum/distal colon
- Sporadic polyps has no malignant potential, (J polyposis increases risk of CR cancer)
What is Peutz-Jeghers syndrome?
Rare autosomal dominant condition resulting in multiple GI tract polyps (mostly in small bowel but can occur in colon)
Associated with cancers, especially in small bowel
How are adenomas histologically classified?
Architectural type - villous, tubulovillous or tubular
Low grade dysplasia or high grade dysplasia
What is the adenoma-carcinoma sequence?
Small % of adenomas will progress to adenocarcinoma within 10-15 years
Dependent on size, villous vs tuberous, and severity of dysplasia
Name two conditions which increase inherited susceptibility to colorectal cancer?
- Familial Polyposis (APC tumour suppressor gene mutation) - multiple adenomas along bowel
- Hereditary Non-Polypoidal Colorectal Cancer (mutation of MLH1, MSH2 DNA mismatch repair genes)
How are colorectal cancers staged?
Dukes stage
TMN scale
What is the pathology of diverticula?
Thickening of muscular propria (pre-diverticula)
Elastosis of teniae coli (shortening of colon)
Mucosal fold develop with shortening
Sacculations then diverticula
What are the clinical features of diverticular?
Asymptomatic (90-99%)
10-30% - acute and chronic complications
