CP11-3 Lower GI Pathology Flashcards
What are the two subtypes of IBD?
Ulcerative colitis and Crohn’s disease
What is the epidemiology of IBD?
Ulcerative colitis = 5-15 cases per 100,000 - increased in urban areas
Crohn’s disease = 5-10 cases per 100,000
Peak age incidence = 20-40 year olds
More common in western countries like UK, Scandinavia, Northern Europe and USA
who is more likely to have chronic disease? Men or women?
Women
what are risk factors for IBD?
Smoking for Crohn’s (not UC)
Oral contraceptive pill
Childhood infections
Domestic hygiene
What are two protective factors for UC?
Smoking
Appendectomy in childhood
How do patients present with UC?
Diarrhoea with urgency and increased frequency - sometimes constipation but less common
Rectal bleeding
Abdominal pain
Associated weight loss - potentially anorexia
Anaemia
What are complications of UC?
Toxic megacolon and perforation
Haemorrhage
Stricture (rare)
Carcinoma in chronic uncontrolled disease
What is the pathology of UC?
Continuous superficial inflammation, mainly of the mucosa, which usually starts distally in the rectum and extends proximally. Can show confluence ulceration. Never transmembrane inflammation and granulomas uncommon.
What are symptoms of Crohn’s disease?
Chronic relapsing disease
Diarrhoea (can contain blood)
Colicky abdominal pain
Palpable abdominal mass
Weight loss
Fever
Oral ulcers
Anaemia
What is the pathology of Crohn’s disease?
Affects GI tract from mouth to anus with majority patients affected in the ileocolic area. It has skin lesions of deep, transmural inflammation and fistulation. Granulomas are common.
What are some complications of Crohn’s disease?
Toxic megacolon
Perforation
Fistulation
Strictures (common)
Haemorrhage
Carcinoma
Short bowel syndrome due to repeated resections
What are some extra-intestinal manifestations of IBD?
Fatty change and granuloma formation in the liver
Polyarthitis
Oral ulcers
Uveitis and retinitis
Amyloidosis
Thrombosis-embolic disease
What is ischaemic bowel disease?
Acute, intermittent or chronic reduction of blood flow in the colon due to occlusion or non-occlusive causes, majority due to an arterial embolism (40-50%). It is usually multifactorial and associated with other vascular diseases.
What are the main types of ischaemic colitis?
Transient (>80%)
Chronic segmental ulcerating with ischaemic stricture
Acute fulminant and gangrenous
How do patients with ischaemic colitis present?
Acute onset cramping abdominal pains
Urgent need to poo
Blood diarrhoea
Rectal bleeding
Symotom improvement within 48 hours and recovery takes 1-2 weeks
What percentage of patients with ischaemic colitis require surgery for colonic infarction?
20%
where is ischaemic colitis most common?
Left colon especially round the splenic flecture
What is diverticular disease?
When there are protrusions of mucosa and submucosa through the bowel wall.
Where are protrusions form diverticular disease most commonly found?
In the sigmoid colon - less commonly in proximal colon
What are the two types of diverticular disease?
True congenital diverticulum
Acquired false pseudo diverticulum
What is the epidemiology of diverticular disease?
Common in western world, rare elsewhere
Urban > rural areas
Male = females
Less common in vegetarians
More common in those with a low fibre diet
Increases with age
What is the pathogenesis of diverticular disease?
Increased intra-luminal pressure causes irregular, uncoordinated peristalsis causing overlapping semi circular arcs of the bowel wall. This causes areas of relative weakness in the bowel wall.
How do patients with diverticular disease present?
Asymptomatic for most part
But can present with cramping abdominal pain and alternating diarrhoea and constipation
What are acute complications of diverticular disease?
Diverticulitis
Peri-diverticular abscesses
Perforation
Haemorrhage
What are chronic complications of diverticular disease?
Intestinal obstructions (5-10% of which are due to strictures)
Fistulas e.g. with bladder or vagina
Diverticular colitis -(segmental and Granulomatous)
Polypoid prolapsing mucosal folds
What are colorectal polyps?
Mucosal protrusions of the lower GI tract due to mucosal or sub mucosal pathology or a lesion deeper in the bowel. They can be solitary of multiple, small or large and appear pedunculated, sessile or flat.
How are polyps classified?
If neoplastic, haemartomatous, inflammatory or reactive
If benign or malignant
If epithelial or mesenchymal
What are the two subtypes of haemartomatous polyps?
Peutz-jeghers
Juvenile
What are characteristics of hyper plastic polyps?
Common
1-5 mm
Often multiple
Located in rectum and sigmoid colon
No distal potential
What is Peutz-Jeghers syndrome?
An autosomal dominant disease characterised by multiple polyps predominantly in the small bowel with have muco-cutaneous pigmentation. They cause abdominal pain, GI bleeding and anemia, presenting in teens and early 20s. It increases risk of cancer.
What are adenomas of the large bowel?
Benign tumours of the epithelium of the colon which are commonly polypod and evenly distributed around the colon They are pre cursers to colorectal cancer.
What is the epidemiology of large bowel adenomas?
25-35% of > 50s
How do adenomas in the large bowel appear macroscopically?
Pedunculated
Sessile
Flat
What different architectural types of colon adenomas are there?
Villous, tubulo-villous or tubular
What is the epidemiology of colorectal cancer?
3rd most common cancer globally
What are 3 hereditary causes of colorectal cancer?
FAP
Lynch syndrome
What factors are protective against colorectal cancer?
Fibre/folate
Aspirin (NSAIDs)
Oral contraceptives
What are some risk factors of colorectal cancer?
Diet (high in fat and red meat)
Obesity
Low physical activity
Alcohol
Pelvic radiation
UC and Crohn’s
What is FAP?
Familial adenomatous polposis, an autosomal dominant condition with mutation of the APC tumour suppressor genes which is associated with multiple benign adenomatous polyps which give you a 100% lifetime risk of large bowel cancer (unless attenuated FAP).
What is Lynch syndrome?
An autosomal dominant genetic condition causing mutations in DNA mismatch repair genes. This causes increased risk of various cancers in abdominal organs e.g. endometrium, small bowel and urinary tract. Causes a 50-70% of lifetime risk for cancer.
Where are most colorectal cancers found?
In rectum - followed by sigmoid colon then caecum
What is the most common subtype of bowel cancer?
Adenocarcinomas
What is an example of a common neoplastic colorectal polyp?
Tubular adenoma.
