Lower GI Pathology Flashcards
What are colorectal polyps
Growths of the mucosa into the luminal surface of the bowel
What is a colorectal carcinoma?
When colorectal polyps become invasive
Anatomical features of the colon?
Extends from terminal ileum to anal canal
1-1.5m
SMA supplies caecum to splenic flexure
IMA supplies remainder of colon to rectum
Caecum -> Ascending colon -> hepatic flexure -> transverse colon -> splenic flexure -> descending colon -> rectum
Ways of classifying colorectal polyps
Benign vs. malignant
Non neoplastic vs. neoplastic
Symptoms of left sided polyps
Frank blood
Constipation
Diarrhoea
Obstruction
Symptoms of right sided polyps
Less overt blood Intussusception (rare) Constipation Diarrhoea Obstruction
Inflammatory Polyps features
Non-neoplastic
Mix of epithelial and stromal elements
May be associated with IBD, surgical anastomosis or other inflammation
- 10-20% of UC patients have them
Histology of inflammatory polyps
- relatively normal
- polypoid shape
- ulceration/erosion/distortion of crypts
Differential diagnoses of inflammatory polyps
Juvenile Polyp
Pyogenic granuloma
Features of hyperplastic polyps
- serrated!
- not dysplastic
- asymptomatic
- most common polyp
- up to 5mm in size
- left sided
Features of sessile serrated lesions/adenomas
- neoplastic
- premalignant features
- > 10mm in size
What mutation are sessile serrated lesions/adenomas associated with?
BRAF mutation
Histology of sessile serrated lesions/adenomas?
- serrated
- crypt dilatation
- may have low or high grade dysplasia
Features of traditional serrated adenomas?
- left sided often
- tubulovillous archiecture
Features of hamartomatous polyps
Rare
Tend to occur in children and young adults
What is an example of hamartomatous polyp?
Peutz-Jegher
Feature of Peutz-Jegher polp?
Hamartomatous polyps
- aborising/tree like SM
- can have dysplasia and adenocarcinoma
What is the criteria for Peutz-Jegher syndrome?
- 3 or more PJ polyps
- any number of PJ polyps with a FH of PJS
- characteristic mucocutaneous pigmentation with FH of PJS
- any number of PJ polyps and mucocutaneous pigmentation
Features of juvenile polyps
- most common type in children
- sessile or pedunculated
- 5-50mm in size
Histology of juvenile polyps
Similar to inflammatory polyps but usually have cystically dilated crypts
Juvenile polyps syndrome criteria
- 5 or more juvenile polyps in colorectum or - juvenile polyps throughout GI tract or - any number of juvenile polyps + FH
Inheritance of juvenile polyps syndrome
Autosomal dominant
Features of adenomas
- common
- dysplastic polyps
- sporadic mostly but can be familial
- premalignant lesion
What is the most common adenoma type?
Tubular adenoma
What are tubular adenomas associated with?
Smoking
High BMI
Red meat
Risks of invasion of tubular polyps
Villous component
High grade dysplasia
1cm to 2cm in size risk goes from 1% to 10%
More than 3 of them
What does a follow up of polyps depend upon?
Presence of invasive carcinoma
Number of polyps
Size of polyps
Presence of villous architecture, high grade dysplasia
Adenoma to Carcinoma sequence
5-20 years for progression
Various mutations = APC, beta catenin, KRAS, TP53
Microsatellite instability
What are the majority of colorectal cancers?
Glandular - adenocarcinoma
Who is most likely to get colorectal cancer?
Men>women
60-79 years
Left side > right side
If before 40yrs then probably related to a syndrome = poor outcomes
RF of colorectal cancer
Older age Obesity Physical inactivity Alcohol consumption IBD FH Polyposis syndromes Dietary - low fibre, increased beef consumption
Polyposis syndrome examples
Juvenile polyposis
PJS
FAP
Lynch
Presentation of adenocarcinoma right sided
Anaemia
Pain
Asymptomatic?
Presentation of left sided adenocarcinoma
Change in bowel habits
Rectal bleeding
Asymptomatic?
Screening for colorectal cancer
Colonoscopy
Faecal occult blood test
Common sites of metastases
Lymph nodes Liver Peritoneum Lung Ovaries
Staging of colorectal cancer
TNM
T1-4
Infiltrates through the mucosa = perforated = T4
Prognosis of colorectal cancer
5 year survival
Most recurrences within 2 years
Poor prognostic features of colorectal cancer
High stage Positive margins Poor differentiation Tumour budding Tumour perforation involvement of peritoneal cavity
Types of colorectal cancer
Adenocarcinoma & subtypes
Adenosquamous carcinoma
Squamous cell carcinoma
Neuroendocrine carcinoma
Other forms of inflammatory bowel disease which are not IBD
Infective colitis Ischaemic colitis Microscopic colitis Diversion colitis Diverticular disease Radiation colitis Drug related colitis Eosinophilic colitis
Features of UC
Relapsing remitting
Inflammation limited to the mucosa
Involves large bowel only
Features of Crohn’s disease
Recurrent granulomatous
Transmural inflammation
Involves any part of GI tract
Epidemiology of UC
- common
- any age but 20-25 then 70-80
- mostly mild
- 1 relapse every 10yrs for most
Epidemiology of Crohns
- Western
- teens/twenties and 50-69
- Caucasian
- can have concordance in monozygotic twins
Distribution of UC
- starts in rectum and spreads proximally
- continuous
- may develop patchy involvement only due to treatment effect
- ileal changes in 17%
Distribution of Crohns
- small intestine
- 40% colonic
- discontinous
Presentation of UC
- relapsing
- bloody mucoid diarrhoea
- pain, cramps
- relieved by defecation
- months-days
Presentation of Crohns
- episodic
- mild diarrhoea
- fever
- pain
- anaemia
- GF
- 20% abrupt onset
Macroscopic features of UC
- active = red, granular, friable, oedematous mucosa
- quiescent = atrophic, featureless mucosa
Macroscopic feature of Crohns
Thickened rigid bowel
Granular scarred serosa
Apthoid, fissuring and serpiginous ulcers with cobblestoning
Local complications of UC
- malignant change
- acute fulminant colitis = acute dilatation of transverse colon = extensive ulceration, transmural inflammation and perforation
Local complications of Crohns
Strictures = obstruction
Fistula = between bowel and abdominal viscera or between bowel and skin
Malabsorption
Perianal disease
Systemic complications of UC
Skin = erythema nodosum, pyoderma gangrenosum Joints = seronegative polyarthritis Eye = iritis, episcleritis Kidney = calculi, pyelonephritis Liver = sclerosing cholangitis
Systemic complications of Crohns
Skin= erythema nodosum, pyoderma gangrenosum Joints = seronegative polyarthritis Eye = iritis, episcleritis Kidney = calculi, pyelonephritis Amyloidosis NO LIVER
Carcinoma in IBD
- more in UC than Crohns
- varied risk
- depends on duration of disease, age of onset, extent of disease
- poorly differentiated
- poor prognosis
