21. Large Bowel Tumours Flashcards

1
Q

What is a polyp?

A

Mass arising form mucosal epithelium or submucosa, protruding into the lumen

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2
Q

What are the types of non-neoplastic polyps?

A

Hyperplastic
Hamartomatous (Juvenile and Peutz-Jehger)
Inflammatory
Lymphoid

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3
Q

What are hyperplastic polyps?

A

Glands with goblet cells and serrated appearance
Due to delayed shedding of surface epithelium
Very common in people over 60

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4
Q

What are juvenile polyps?

A

Hamartomatous malformations of bowel mucosa

Dilated glands and inflamed stroma

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5
Q

What are juvenile polyps known as in adults?

A

Retention polyps

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6
Q

What description is used for Peutz-Jegher polyps?

A

Christmas tree

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7
Q

What is Peutz Jegher syndrome?

A

AD
Mucocutaneous pigmentation
Polyps throughout GIT
Increase risk of pancreas, breast, lung, ovary and uterine cancers

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8
Q

What is Cowden syndrome?

A

AD: mutation in PTEN gene
Multiple hamartomatous polyps and skin tumours
Increased risk of thyroid and breast cancer

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9
Q

What is Cronkhite Canada syndrome?

A

Hamartomatous polyps
Nail atrophy
Skin pigmentation

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10
Q

What are inflammatory polyps?

A

Inflamed regenerative mucosa surrrounded by ulcerated tissue

Seen in IBD

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11
Q

What are neoplastic polyps?

A

Proliferation of dysplastic epithelium
Precursor to carcinoma
Can be tubular, villous (higher risk) or tubulovillous

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12
Q

What are the clinical features of neoplastic polyps?

A

Asymptomatic
Bleeding, iron deficiency anaemia
Protein loss
Obstruction

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13
Q

What gene is mutated in FAP?

A

APC gene on 5q21

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14
Q

What is the treatment for FAP?

A

Remove whole colon as 100% risk of carcinoma in 10-15 years

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15
Q

Name 2 variations of FAP

A

Gardener’s

Turcot’s

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16
Q

What is Gardener’s syndrome?

A

many benign tumours, abnormal teeth

Increased risk of duodenal and thyroid cancer

17
Q

What is Turcot’s syndrome?

A

Colorectal adenomatous polyps

Brain tumours

18
Q

What are the risk factors for colonic adenocarcinoma?

A

Adenomatous polyps
Hereditary syndromes (Lynch and FAP)
IBD
Diet, obesity, physical inactivity

19
Q

What are the features of colonic adenocarcinoma in Lynch syndrome?

A

No adenoma-carcionoma sequence (straight to carcinoma)

Usually right sided

20
Q

What are the differences between type 1 and 2 lynch syndrome?

A

1 is just increased risk of colon cancer

2 has an increased risk of colon cancer, and endometrial and ovarian

21
Q

What is lynch syndrome caused by?

A

Defect in mismatch repair genes

22
Q

What infection is associated with colonic carcinoma?

A

Strep bovis endocarditis

23
Q

What are the macroscopic features of right sided adenocarcinoma?

A

‘Cauliflower’ appearance

May ulcerate and bleed: iron deficiency anaemia

24
Q

What are the macroscopic features of left sided adenocarcinoma?

A

More likely to encircle the colon in a ‘napkin ring’ appearance
Causes constriction and obstruction as left sided lumen is narrow and faeces are more solid
Poorer prognosis

25
Q

What are the histological features of adenocarcinoma of the bowel?

A

Produce mucin
Signet ring appearance (mucin)
CEA marker

26
Q

Where is colonic carcinoma most likely to metastasise to?

A

Liver and Lungs

27
Q

What staging system is used for colonic adenocarcinoma?

A

Duke’s staging

28
Q

Why are NSAIDs protective against colonic adenocarcinoma?

A

Reduce proliferation and angiogenesis

Increase apoptosis

29
Q

What are the targeted treatment options for colonic adenocarcinoma?

A

Cetuximab and panitumumab block EGFR signalling pathoway

Bevacizumab prevents angiogenesis

30
Q

What must be done before prescribing cetuximab?

A

Use PCR to make sure there is no mutation in k-ras or the patient will not respond to therapy

31
Q

Which organs metastasise to the colon?

A

Melanoma
Ovary
Endometrial
Prostate

32
Q

Why does carcinoid syndrome only affect the right heart?

A

5-HT is broken down in the lung so never gets to the left heart

33
Q

Which cells do GISTs originate in?

A

Interstitial cells of Cajal

34
Q

What mutations are associated with GISTs?

A

Platelet Derived Growth Receptor a mutation

c-kit proto-oncogene

35
Q

Which therapy targets the c-kit oncogene?

A

Imatinib

36
Q

Is B or T cell lymphoma more common in the GIT?

A

B cell; all except EATL