Pathology of the colon Flashcards by Jack Molyneux

What is a polyp?

A protrusion above an epithelial surface

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What are the 3 main appearances of polyp?

Pedunculated
Sessile
Flat

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What is meant by a pedunculated polyp?

This means that the head of the polyp is attached via a “cord” to the epithelium

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What is meant by a sessile polyp?

The poly is carpet like and so forms small protruding fibres

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What are the 2 main origins of polyps?

Epithelial
Mesenchymal

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What are some forms of benign polyp?

Adenoma
Inflammatory polyps
Juvenile polyps
Peutz-Jeghers syndrome

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What are adenomas?

These are benign, non-invasive tumours of the colon which can progress into adenocarcinoma if left untreated

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What are the 3 histological classes of adenoma?

Tubular
Villous
Tubulovillous

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What is meant by a villous adenoma?

A polyp that branches out into finger-like projections

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What is meant by a tubular adenoma?

A polyp that has crypt like inward protrusions

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What must be done with all adenomas?

Removal, either surgically or endoscopically

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Where are most colonic adenocarcinomas found?

Left side (Rectum, sigmoid and descending colon)

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How will left sided colonic adenocarcinoma usually present?

Blood PR
Altered bowel habit
Obstruction

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How will right sided colonic adenocarcinoma usually present?

Anaemia
Weight loss

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What is the primary treatment of colonic adenocarcinoma?

Surgery, involving removal of the affected region of the colon, before sending it off to pathology for staging

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Where are some possible places of invasion in colonic adenocarcinoma?

Mesorectum
Peritoneum
Mesentery
Liver
Bladder

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What are some genetic conditions that can predispose to colonic adenocarcinoma?

HNPCC - Lynch syndrome
FAP - Familial Adenomatous Polyposis

How will adenocarcinoma as a result of Lynch syndrome usually present?

Right sided tumours
<100 mucinoid polyps
Crohn’s like inflammatory response

How will colonic adenocarcinoma as a result of familial adenomatous polyposis usually present?

Polyps throughout the colon
>100 polyps of no particular type
No inflammatory response
Association with desmoid and thyroid tumours

What is diverticular disease?

This is a condition resulting in herniation of the intestinal mucosa through the muscular wall, causing many small outpouchings

How do diverticulae form?

A low fibre diet will decrease water in the colon, causing increased intraluminal pressure, required to pass stools
This increased intraluminal pressure causes herniation of the mucosa

How will diverticular disease present?

No symptoms - 75% of cases
Left iliac fossa pain
Altered bowel habit

Where is the most common sight for diverticular disease?

Sigmoid colon as it has the highest pressure

What are some investigations that can be performed in diverticular disease?

Barium enema
Sigmoidoscopy

What are some possible complications of diverticular disease?

Inflammation Rupture Abscesses Fistulas Massive bleeding

What are some treatment options in diverticular disease?

High fibre diet High fluid intake Laxatives (Avoid stimulant) Analgesics Surgical resection

What is ischaemic colitis?

This is inflammation of the large intestine caused by ischaemia

What is the most commonly affected area of the large intestine in ischaemic colitis?

Left side in the elderly

What are some conditions that can cause ischaemia colitis?

Cardiovascular disease Atrial fibrillation Embolism Atherosclerosis of mesenteric arteries Shock Vasculitis

How will ischaemic colitis show on endoscopy?

Affected area will appear highly erythematous and segmented

How will ischaemic colitis appear histologically?

Withering of crypts and smudging of the lamina propria with few chronic inflammatory cells

What are some possible complications of ischaemic colitis?

Massive bleeding Rupture Stricture due to fibrosis

What is antibiotic-induced colitis?

This is a condition that occurs due to destruction of the normal gut microbiota, allowing growth of a more resistant bacteria

What is the most common causative bacteria in anti-biotic induced colitis?

Clostridioides difficile

How will antibiotic-induced colitis present on colonoscopy?

White pseudomembrane of exudate on the intestinal wall

What 2 conditions fall under the class of microscopic colitis?

Collagenous colitis Lymphocytic colitis

What is meant by a microscopic colitis?

Colitis that causes changes only visible histologically

What is meant by collagenous colitis?

This is inflammation of the small intestine, caused by a thickened collagen band, comprised from the basement membrane

How will collagenous colitis present?

History of water diarrhoea No chronic architectural changes Normal endoscopy and drug history Patchy disease associated with intraepithelial inflammatory cells on histology

What is lymphocytic colitis?

This is inflammation of the intestinal wall due to the influx of intraepithelial lymphocytes, associated with coeliac's disease

What is peutz-jegher's syndrome?

This is a rare genetic disorder resulting in the formation of hamartomatous GI polyps

How does Peutz-Jegher's syndrome present?

Brownish or bluish-gray spots on the lips, gums, inner lining of the mouth, and skin Clubbed fingers or toes Cramping pain in the belly area Dark freckles on and around the lips of a child Hamartomatous GI polyps