Pathology of the Colorectal Carcinoma

Question 1

What is a polyp?

Answer 1

A protrusion above an epithelial surface

Its a tumour/swelling

Question 2

What could be the differential diagnosis of a colonic polyp?

Answer 2

Adenoma
Serrated polyp
Polypoid carcinoma
Other

Question 3

What shapes of polyps can you get?

Answer 3

Flat 
Sessile 
Pedunculated 
Long stalk 
Irregular surface

Question 4

Describe adenoma of the colon?

Answer 4

Benign
Non invasive - doesnt metastasise

Dysplastic tumour of columnar cells of glandular tissue
Can be derived from polyps but not all are, all adenomas may form adenocarconima

Question 5

What types of histological things might you see in an adenoma polyp?

Answer 5

Tubullovillous
Tubular
Villous

Question 6

Are all adenomas non dysplastic or dysplastic?

Answer 6

All adenomas are dysplastic

Question 7

Describe the adenoma-carcinoma sequence?

Answer 7

Normal mucosa –> adenoma (dysplastic) –> adenocarcinoma (invasive)

Question 8

Do adenomas need to be removed?

Answer 8

YES - all adenomas need to be removed as they are premalignant, either done endoscopically or surgically

Question 9

Do all colorectal adenomas have the same molecule genetic origins?

Answer 9

No - they can have separate pathways for inherited tumours, separate pathways for serrated adenomas

Question 10

What is usually the primary treatment in most cases of adenocarcinomas?

Answer 10

Surgery

Colon/rectum is removed and sent to pathology for staging

Question 11

Describe dukes staging of colorectal carcinoma?

Dukes, A, B and C

Answer 11

Dukes A - confined by muscular propria
Dukes B - thought the muscular propria
Dukes C - metastatic to lymph nodes

Question 12

Describe where colorectal carcinoma might spread?

Answer 12

Local invasion - mesorectum, peritoneum, other organs

Lymphatic - mesenteric nodes

Haematogenous - liver, distant sites

Question 13

Name 2 inherited cancer syndromes?

Answer 13

Hereditary non polyposis coli (HNPCC)

Familial adenomatous polyposis (FAP)

Question 14

Describe HNPCC?

Answer 14

Hereditary non polyposis colon cancer

Mutation in DNA mismatch repair gene responsible to maintaining stability of DNA replication

Late onset

Autosomal dominant

Inherited mutation in MLH-1 MSH-2 PMS-1 or MSH-6

< 100 polyps

Right side tumours

Crohn’s like inflammatory response

Question 15

Describe FAP?

Answer 15

Familial adenomatous polyposis

Early onset
Autosomal dominant

Inherited mutation in the FAP gene

Caused by a germline mutation on the APC gene

> 100 polyps

It is throughout the colon

There is no specific inflammatory response

Question 16

What is the muscular propria?

Answer 16

The same as the muscular externa (has 2 layers of muscle, circular and longitudinal)