Intestinal Problems 4 - Colorectal Carcinoma Pathology

Question 1

Normal appearance of the large bowel?

Answer 1

Flat with no villi but contains straight crypts lined by absorptive and mucus-producing goblet cells

Question 2

What is a polyp?

Answer 2

An abnormal growth of tissue projecting from a mucous membrane (it is a swelling and therefore a tumour)

Question 3

What are the general categories of benign epithelial polyps with examples? (4)

Answer 3

Neoplastic e.g. adenomaInflammatory e.g. in inflammatory bowel diseaseHamartomatous (different to neoplasm as if the tissue stops growing the polyp will too) e.g. juvenile polypMetaplastic (or hyperplastic)

Question 4

What are the general malignant types of colon polyps (tumours) found in the epithelium?

Answer 4

Polypoid e.g. adenocarcinomasCarcinoid polyps

Question 5

What are the 5 types of benign mesenchymal tumours?

Answer 5

Lipoma (fat)Lymphangioma (lymphatics)Haemangiomas (vascular)Fibromas (fibrous/ connective tissue)Leiomyoma (smooth muscle)

Question 6

What are 2 possible malignant mesenchymal polyps that develop in the large intestine?

Answer 6

SarcomasLymphomatous polyps

Question 7

What are the differential diagnosis of a colonic polyp? (4)

Answer 7

AdenomaSerrated polyp (“saw-tooth” like structure)Polypoid carcinomaOther *need histopathology to tell them apart

Question 8

Macroscopic descriptions of a polyp (5)?

Answer 8

Pendunculated (attached via a stalk)Sessile (like a carpet - harder to treat)Flat (barely prude above the peithelial surface)Irregular surfaceLong stalk

Question 9

What is a polyp which has a dysplastic epithelial lining on histopathological examination?

Answer 9

Adenomas (adenomas are always dysplastic but not all dysplasia is adenomas - mostly is)

Question 10

Do adenomas invade or metastasise?

Answer 10

No - they can becomes adenocarcinomas however

Question 11

What are the 3 microscopic appearances of adenomas?

Answer 11

Tubular (contains tubular crypts)Villous (velvety surface made up from numerous epithelium-lined projections)Tubullovillous (mixture of both of the above features)

Question 12

What is the 5 stages of the adenoma-carcinoma sequence?

Answer 12

Normal mucosaSmall Adenoma (dysplastic)Large adenoma (dysplastic)Adenocarcinoma (invasive)Metastases

Question 13

Main genetic mutations that cause normal epithelium to develop a small adenoma? (5)

Answer 13

APC mutationMCC mutation5q deletionc-myc activationbci-2 mutation(not all adenomas have the same molecular genetic origins - separate pathways for inherited tumours and serrated adenomas)

Question 14

Main 2 genetic mutations that cause a small adenoma to become a large adenoma?

Answer 14

K-ras mutationc-yes mutation

Question 15

Main 3 genetic mutations that causes a large adenoma to become an invasive adenocarcinoma?

Answer 15

Chromose 17p18qp53 mutation

Question 16

Main mutation that causes invasive adenocarcinoma to metastasise?

Answer 16

nm23 deletion

Question 17

Do adenomas have to be removed?How are they removed? (2)

Answer 17

Yes as they are all premalignantEither endoscopically or surgically

Question 18

How are malignant tumours of the large bowel removed?

Answer 18

Surgically (as they tend to be quite big) - mesentery is removed at the same time in order to get rid of the lymph nodesRemoved section is sent to pathology for staging

Question 19

What types of cancers are most large bowel malignant tumours?

Answer 19

Adenocarcinoma

Question 20

Microscopic features of large bowel cancers?

Answer 20

Moderately differentiated”dirty” necrosis patternInvades through muscularis propria

Question 21

Colorectal carcinoma staging method?

Answer 21

Dukes (predicts prognosis)

Question 22

Dukes staging for colorectal carcinoma + 5 year survival?

Answer 22

Dukes A = confined by muscularis propria - 90+%Dukes B = through muscularis propria - 75%Dukes C = metastatic to lymph nodes - 50-60%

Question 23

what is the most common side to develop colorectal carcinoma?What are the common side effects for this sided colon cancer? (3)

Answer 23

Left sided - 75%Blood PRAltered bowel habitObstruction(tend to be more genetic related)

Question 24

What % of colorectal cancers are right sided (caecum and ascending)?What are the presenting complaints for this? (2)

Answer 24

25% right sided Anaemia, weight loss(tend to be more dietary related)

Question 25

What are 3 examples of gross appearance of colorectal carcinomas?

Answer 25

PolypoidStricturingUlcerating(varied gross appearance)

Question 26

What is the typical histopathological appearance of colorectal carcinomas?

Answer 26

Adenocarcinomas

Question 27

Where do colorectal carcinomas tend to locally invade? (3)

Answer 27

MesorectumPeritoneumOther organs

Question 28

Where do colorectal carcinomas lympatically spread?

Answer 28

Mesenteric nodes

Question 29

Where do colorectal cancers tend to spread maematogenously?

Answer 29

Liver, distant sites

Question 30

What are 2 inherited cancer syndromes which cause multiple polyps?How many polyps does each tend to cause?Onset?Autosomal dominant/ recessive?

Answer 30

Hereditary non polyposis coli (HNPCC) - 100 polyps - tends to have an early onset with many patients having their colon removed in their teenage years to prevent them dining of colorectal cancerBoth autosomal dominant

Question 31

In both HNPCC and FAP, what is the defect in?What genes are the inherited mutation in?

Answer 31

HNPCC - defect in DNA mismatch repair-MLH-1, MSH-2, PMS-1 or MSH-6 genes mutatedFAP = defect in tumour supressionInherited mutation in FAP gene

Question 32

Where are the polyps found in HNPCC and FAP?

Answer 32

Right sided in HNPCCThroughout the colon in FAP

Question 33

What type of tumours develop in HNPCC and FAP?

Answer 33

Mucinous in HNPCCAdenocarcinoma in FAP

Question 34

Inflammatory responses in HNPCC and FAP?

Answer 34

HNPCC - chron’s like inflammatory responseFAP - no specific inflammatory response

Question 35

What other carcinomas are HNPCC and FAP associated with?

Answer 35

HNPCC - gastric and endometrial carcinomaFAP - desmoid tumours and thyroid carcinoma