Lower Gastrointestinal Pathology Flashcards
what is diverticulosis of the colon?
where is it usually located?
Protrusions of mucosa and submucosa through the bowel wall
it commonly occurs in the sigmoid colon
located between mesenteric and anti-mesenteric taenia coli
less commonly extends into the proximal colon (e.g. caecum) (15%)
What are the 2 different types of diverticula of the large bowel?
True “congenital” diverticulum or acquired “false” / “pseudo” diverticulum
what is significant about the pouches in diverticulosis?
why do they usually occur?
There are multiple pouches in the colon that are NOT inflamed
The outpockets of colonic mucosa and submucosa occur due to weaknesses of muscle layers in the colon wall
they typically cause no symptoms
What is the epidemiology of diverticulosis like?
- Common in developed (western) world
- Rare in Africa, Asia & South America
- common in urban areas
- changing prevalence in migrant populations
- relationship with fibre content of the diet
How does diverticulosis vary with age and gender?
What other lifestyle choice is important?
It increases with age:
- < 40 - rare
- 40 - 60 - 10%
- >60 - 30%
- >90 - 50%
it occurs equally in males and females
it is less common in vegetarians
what is involved in the pathogenesis of diverticulosis of the colon?
Increased intra-luminal pressure:
- irregular, uncoordinated peristalsis
- overlapping (valve like) semicircular arcs of bowel wall
Points of relative weakness in the bowel wall:
- penetration by nutrient arteries between mesenteric and antimesenteric taenia coli
- age related changes in connective tissue
what are the clinical features of diverticular disease?
What % experience complications?
- Asymptomatic in 90 - 99% of cases
- cramping abdominal pain
- alternating constipation and diarrhoea
- 10-30% experience acute and chronic complications
what are some of the acute complications of diverticular disease?
- Diverticulitis / peridiverticular abscess (20-25%)
- perforation
- haemorrhage (5%)
What are some of the chronic complications of diverticular disease?
- Intestinal obstruction (strictures in 5-10%)
- fistula (urinary bladder, vagina)
- diverticular colitis (segmental and granulomatous)
- polypoid prolapsing mucosal folds
What is this?
Diverticular (peri-colic) abscess due to acute diverticulitis
what is this?
Diverticular perforation with acute purulent peritonitis
What is colitis?
What are the 2 different types and what inflammation does it usually involve?
Colitis is inflammation of the colon
it is usually mucosal inflammation but is occasionally transmural (e.g. Crohn’s disease) or predominantly submucosal/muscular (e.g. eosinophilic colitis)
it is acute (days to a few weeks) or chronic (months to years)
what are examples of acute colitis?
- Acute infective colitis - e.g. campylobacter, shigella, salmonella, CMV
- antibiotic associated colitis
- drug induced colitis
- acute ischaemic colitis (transient or gangrenous)
- acute radiation colitis
- neutropenic colitis
- phlegmonous colitis
What are examples of chronic colitis?
- Chronic idiopathic inflammatory bowel disease
- ischaemic colitis
- diverticular colitis
- microscopic colitis (collagenous & lymphocytic)
- chronic infective colitis (e.g. amoebic colitis & TB)
- diversion colitis
- eosinophilic colitis
- chronic radiation colitis
what are examples of idiopathic inflammatory bowel disease?
- Ulcerative colitis
- Crohn’s disease
- unclassified & indeterminate colitis (10-15%)
What is the incidence of IBD like?
In what countries is it the highest and lowest?
UC - 5-15 cases per 100,000 p.a.
CD - 5-10 cases per 100,000 p.a.
incidence is highest in Scandinavia, UK, Northern Europe and USA
incidence is lower in japan, Southern Europe and Africa
what is the peak age incidence of IBD?
Are UC and CD more common in males or females?
Peak age incidence is 20-40 years of age
Crohn’s disease is more common in females 1.3:1
ulcerative colitis is equally common in males and females
(incidence is higher in urban areas)
What are other risk factors involved in the epidemiology of IBD?
- Cigarette smoking
- increases risk of UC by 0.5x and CD by 2x
- oral contraceptive
- increases risk of UC by 1.4x and CD by 1.6x
- childhood infections
- domestic hygiene
- appendiceectomy (protective against UC)
What is meant by familial clustering in IBD?
What is your risk of UC and Crohns if a first degree relative has each disease?
what is the clinical presentation of ulcerative colitis like?
- Diarrhoea (66%) with urgency / tenesmus
- constipation (2%)
- rectal bleeding (>90%)
- abdominal pain (30-60%)
- anorexia
- weight loss (15-40%)
- anaemia
What are the complications of ulcerative colitis?
- Toxic megacolon and perforation
- haemorrhage
- stricture (rare)
- carcinoma
What are the clinical features of Crohn’s disease?
- Chronic relapsing disease
- affects all levels of GIT from mouth to anus
- diarrhoea (may be bloody)
- colicky abdominal pain
- palpable abdominal mass
- weight loss / failure to thrive
- anorexia
- fever
- oral ulcers
- peri-anal disease
- anaemia
What is the distribution of Crohn’s disease like?
- Ileocolic 30-55%
- small bowel 25-35%
- colonic 15-25%
- peri-anal / ano-rectal 2-3%
- gastro-duodenal 1-2%
What are the stages involved in the development of colorectal cancer in ulcerative colitis?
- Inflamed mucosa
- Low grade dysplasia
- High grade dysplasia
- Colorectal cancer
what is the distribution of ischaemic colitis like?
What is this?
Splenic flexure infarct in ischaemic colitis
What is this?
Segmental involvement of terminal ileum, caecum, ascending colon and splenic flexure in ischaemic colitis
what is shown here?
Haemorrhagic infarction due to SMV thrombosis
How big is a hyperplastic polyp?
Where is is located?
Does it have malignant potential?
It is common and 1-5mm in size, but there are often multiple
located in the rectum and sigmoid colon
small distal HPs have no malignant potential
some large right-sided hyperplastic polyps (sessile serrated lesions) may give rise to microsatellite unstable carcinoma (10-15% of all colorectal cancer)
what is a juvenile polyp?
how large are they and where do they tend to occur?
A spherical and pedunculated polyp that is the commonest polyp in children
10-30mm in size
typically occur in the rectum and distal colon
What is the macroscopic appearance, architectural type & histological grade of adenomas?
Macroscopic appearance:
- Pedunculated, sessile or “flat”
Architectural type:
- villous, tubulo-villous or tubular
Histological grade:
- high v low grade dysplasia
what is shown in this image?
Adenoma showing low grade dysplasia
what is shown in this image?
Adenoma showing high grade dysplasia
What conditions can lead to colorectal cancer?
- “Sporadic” average risk is 75%
- FH
- HNPCC
- FAP
- IBD
