- inflammation of the colon - usually mucosal inflammation - occasionally transmural e.g Chron's

Theme 11 L2: Lower GI Pathology Flashcards by Antonia Salem

What is diverticulosis of the colon?

protrusions of mucosa and submucosa through the bowel sall

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Which part of the colon does diverticulosis usually occur?

sigmoid colon - located between the mesenteric and anti-mesenteric taenia coli

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What are the two types of diverticula of the large bowel?

True “congenital” diverticulum

2. Acquired / “false”/ “pseudo” diverticulum

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What food group in the diet are diverticula associated with?

fibre content

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What is the pathogenesis of diverticula of the large bowel?

increased intra-luminal pressure
- irregular, unco-ordinated peristalsis
- over lapping (valve like) semi circular arcs of bowel wall
Points of relative weakness in the bowel wall

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What are the clinical features of diverticular disease?

asymptomatic in 90%
cramping abdo pain
alternating constipation and diarrhiea

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What are the acute complications of diverticular disease?

diverticulitis/ peri diverticular abscess
perforation
haemorrhage

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How does diverticulitis or a peridiverticular abscess arise?

faeces get stuck in diverticulum
bacteria accumulates
causes inflammation or an abscess

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What are the chronic complications of diverticular disease?

intestinal obstruction
fistula
diverticular colitis
polypoid prolapsing mucosal folds

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What is colitis?

inflammation of the colon
usually mucosal inflammation
occasionally transmural e.g Chron’s

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What are the types of acute colitis?

Acute infective colitis e.g campylobacter, salmonella
antibiotic associated colitis
Drug induced colitis
Acute ischaemic colitis (transient or gangrenous)

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What are the two types of chronic colitis?

Chronic idiopathic inflammatory bowel disease

2. Ischaemic colitis

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What are the 3 types of idiopathic inflammatory bowel disease?

ulcerative colitis
crohn’s disease
unclassified and indeterminate colitis

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What are the risk factors for the different IBD?

CD is more common in females, UC has equal incidence
Cigarette smoking is a risk factor for CD, but a protective factor from UC
Oral contraceptive

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What is the clinical presentation of a patient with Ulcerative colitis?

diarrhoea with urgency/ tenesmus
rectal bleeding
abdominal pain
anorexia
weight loss
anaemia

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What are the complications of ulcerative colitis?

toxic megacolon and perforation
haemorrhage
stricture
carcinoma

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What is the clinical presentation of Crohn’s disease?

chronic relapsing disease
affects all levels of GIT from mouth to anus
bloody diarrhoea
abdominal pain/ mass
weight loss/ failure to thrive
anorexia
fever
oral ulcers
peri-anal disease
anaemia

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What are the top 3 sites that Crohn’s disease occurs?

Ileocolic
Small bowel
Colonic

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What is a characteristic feature of Crohn’s disease?

skip lesions - unequal distribution around the GI tract

What are the complications of Crohn’s?

toxic megacolon (colonic distension)
perforation
fistula
stricture
haemorrhage
carcinoma
short bowel syndrome (repeated resection)

What are some extra intestinal manifestations of IBD?

Hepatic
- fatty change and granulomas
- PSC and bile duct carcinoma
Osteo-articular
- polyarthritis
- sacro-ileitis & ankylosing spondylitis
Muco-cutaenous
- oral ulcers
- pyoderma gangrenosum & erythema nodosum
Ocular
- uveitis and retinitis
Systemic
- amyloidosis
- thrombo-embolic disease

What are the risk factors of ColoRectal Cancer in UC?

early age of onset
duration of disease > 10 years
total or extensive colitis
PSC
family history of CRC
severity of inflammation
presence of dysplasia

Explain the development of UC to colorectal cancer?

inflammed mucosa
low grade dysplasia
high grade dysplasia
colorectal cancer

What is ischaemic colitis?

colonic injury secondary to a acute, intermittent or chronic reduction in flow
may be occlusive or non-occlusive

What are the 3 clinical forms of ischaemic colitis?

1. Transient - acute onset cramping abdominal pains; urge to defaecate; bloody diarrhoea 2. Chronic segmental ulcerating (ischaemic stricture) 3. Acute fulminant and gangrenous

What are the 3 causes of mesenteric ischaemia?

1. Arterial embolism 2. Arterial thrombosis 3. Non-occlusive mesenteric ischaemia

What is a colorectal polyp?

- a 'mucosal protrusion' - solitary or multiple (polyposis) - pedunculated, sessile or "flat"

How are colorectal polyps classified?

- neoplastic - hamartomatous - inflammatory - reactive

What are the commonest non-neoplastic polyp in the colo-rectum?

hyperplastic polyps

Where are hyperplastic polyps located?

in the rectum and the sigmoid colon

Why is a small, distal hyperplastic polyp safer than a large hyperplastic polyp?

-small, distal HPs have no malignant potential

What are the two types of hamartomatous polyps?

1. Juvenile polyps | 2. Peutz-Jeghers poylps

What is the classical appearance of a juvenile polyp?

-often spherical and pedunculated

What is the most common type of polyp in children?

juvenile polyp

Where do juvenile polyps typically occur?

rectum and distal colon

Do juvenile polyps have malignant potential?

- sporadic polyps do not have malignant potential | - juvenile polyps associated with increased risk of gastric and colorectal cancer

What is Peutz-Jeghers syndrome?

- autosomal dominant condition - mutation in STK11 gene on chromosome 19 - very rare

How does Peutz-Jeghers syndrome present?

- in teens/20s - with abdo pain, GI bleeding, anaemia, increased risk of cancer - multiple GIT polyps (predominanatly small bowel) - muco-cutaneous pigmentation

Which benign epithelial tumour a precursor of colorectal cancer in at least 80% of cases?

adenomas

What features of an adenoma are associated with a higher risk of malignant change?

- "flat" adenomas - >size - villous and tubule-villous - severe (high grade) dysplasia - lynch syndrome associated adenomas

What are the risk factors for colorectal cancer?

- diet - dietary fibre, fat, red meat, folate, calcium - obesity - alcohol - NSAIDs & aspirin - HRT and oral contraceptives - schistosomiasis - pelvic radiation - UC and Crohn's

What is FAP?

- autosomal domianant familial adenotomatous polyposis | - associated with multiple benign adenomatous polyps in the colon

FAP is due to a mutation in which gene?

APC tumour suppressor gene

What is Lynch syndrome?

- autosomal dominant - 60% lifetime risk of small bowel cancer - due to mutations in DNA mismatch repair genes - increased risk of endometrial, ovarian, gastric, small bowel, urinary tract and biliary tract cancer

Where do 2/3rds of colorectal cancers occur?

left colon between splenic flexure and rectum

what type of tumour are 95% of colorectal cancers?

adenocarcinoma (glandular/ producing mucin)

What are the 4 stages of Dukes staging of colorectal cancer?

Stage A: adenocarcinoma confined to the bowel wall with no lymph node metastasis Stage B: adenocarcinoma invading through the bowel wall with no lymph node metastasis Stage C: adenocarcinoma with regional lymph node metastasis regardless of depth of invasion Stage D: distant mets present