- common - dysplastic polyps - sporadic mostly but can be familial - premalignant lesion

Lower GI Pathology Flashcards by Amrita Heer

What are colorectal polyps

Growths of the mucosa into the luminal surface of the bowel

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What is a colorectal carcinoma?

When colorectal polyps become invasive

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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

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Ways of classifying colorectal polyps

Benign vs. malignant

Non neoplastic vs. neoplastic

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Symptoms of left sided polyps

Frank blood
Constipation
Diarrhoea
Obstruction

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Symptoms of right sided polyps

Less overt blood
Intussusception (rare)
Constipation
Diarrhoea
Obstruction

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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

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Histology of inflammatory polyps

relatively normal
polypoid shape
ulceration/erosion/distortion of crypts

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Differential diagnoses of inflammatory polyps

Juvenile Polyp

Pyogenic granuloma

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Features of hyperplastic polyps

serrated!
not dysplastic
asymptomatic
most common polyp
up to 5mm in size
left sided

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Features of sessile serrated lesions/adenomas

neoplastic
premalignant features
> 10mm in size

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What mutation are sessile serrated lesions/adenomas associated with?

BRAF mutation

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Histology of sessile serrated lesions/adenomas?

serrated
crypt dilatation
may have low or high grade dysplasia

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Features of traditional serrated adenomas?

left sided often

- tubulovillous archiecture

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Features of hamartomatous polyps

Rare

Tend to occur in children and young adults

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What is an example of hamartomatous polyp?

Peutz-Jegher

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Feature of Peutz-Jegher polp?

Hamartomatous polyps

aborising/tree like SM
can have dysplasia and adenocarcinoma

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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

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Features of juvenile polyps

most common type in children
sessile or pedunculated
5-50mm in size

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Histology of juvenile polyps

Similar to inflammatory polyps but usually have cystically dilated crypts

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Juvenile polyps syndrome criteria

- 5 or more juvenile polyps in colorectum
or
- juvenile polyps throughout GI tract 
or
- any number of juvenile polyps + FH

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Inheritance of juvenile polyps syndrome

Autosomal dominant

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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