FN: Colorectal Carcinoma: Pathology and Presentation Flashcards Preview

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Flashcards in FN: Colorectal Carcinoma: Pathology and Presentation Deck (20):
1

Epi

3rd commonest cancer
2nd commonest cause of cancer deaths (16,000/yr)
Age: peak in 60s
Sex: rectal Ca commoner in men
Geo: western disease

2

Colonic adenomas

Benign precursos to CRC
Characterised by dysplastic epithelium

3

Classificatino of colonic adenomas

Tubular
Villous
Tubulovillous

4

Tubular

Small, pedunculated, tubular glands

5

Villous

Large
Sessile
Covered by villi

6

Tubulovillous

Mixture

7

Colonic adenomas presentation

Typically asymptomatic
Large polyps can bleed - IDA
Villous adenomas can - reduced potassium + hypoproteinaemia

8

Colonic aenomas malignant potential

increased size
Increased dysplasia
Increased villous component

9

APC et al:

1. -ve regulator of Beta-catenin (component of WNT pathway)
2. APC binds to and promotes degradation of Beta-catenin
3. APC mutation - rise in Beta-catenin and rise in transcription of genes which promote cell proliferation
4. Proliferation - mutation of other genes which promote growth and prevent apoptosis
- KRAS (proto-oncogene)
-p53 (TSG)

10

Adenoma - Carcinoma Seqeunce

1. First hit: mutation of one APC copy
2. Seconda hit: mutation of second of APC copy --> adenoma formation
3. Additional mutations in adenoma - malignant transformation e.g. KRAS, p53

11

Other aetiological Factors

1. Diet: reduced fibre + raised refined carbohydrate
2. IND: CRC in 15% with pancolitis for 20 yrs
3. Familial: FAP, HNPCC, Peutz-jeghers
4. Smoking
5. genetics:
-no relaticeL1/50 CRC risk
- One 1st degree: 1/10

6. NSAIDS/Aspirin (300mg/d): protective

12

Pathology GI malignancy types

95% adenocarcinoma
Others: Lymphoma, GIST, carcinoid

13

Location

Rectum:35%
Sigmoid:25%
Caecum and ascending colon:20%
Transverse:10%
Descending:5%

14

Proximal tumours

sessile or polypod

15

Distal tumours

Annular stenosing

16

Spread

Local
Lymphatic
Blood (liver, lungs)
Transcoelomic

17

Presentation Left

altered bowel habit
PR mass (60%)
Obstruction (25%)
Bleeding/mucus PR
Tenesmus

18

Presentation right

Anaemia
Wt. loss
Abdominal pain

19

Either side presentation

abdominal mass
Perforation
haemorrhage
Fistula

20

Examination shows

Palpable mass: per abdomen or PR
Perianal fistulae
Hepatomegaly
Anaemia
Signs of obstruction

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