Pathology of Cancer

Question 1

Define neoplasm / tumour.

Answer 1

A neoplasm is a mass of cells that:

1 - Have undergone an irreversible change from normality.

2 - Proliferated in an uncoordinated manner.

3 - Are partially or completely independent of the factors which control normal cell growth.

Question 2

Define cancer.

Answer 2

Cancer is a malignant neoplasm.

Question 3

List 2 requirements of a neoplasm to be considered malignant (cancerous).

Answer 3

A malignant neoplasm (cancer) must:

1 - Invade into the surrounding tissue.

2 - Spread to distant sites to form metastases.

Question 4

Give an example of a neoplasm that behaves in an intermediate manner between malignant and non-malignant.

Answer 4

Basal cell carcinomas of the skin (because it invades local tissues but doesn’t metastasise).

Question 5

What is the tissue of origin of most malignant neoplasms?

What is the tissue of origin of most benign neoplasms?

Answer 5

• Most malignant neoplasms originate from epithelial cells.

- Most benign neoplasms originate from mesenchymal cells.

Question 6

Define differentiation.

How does differentiation usually differ between benign and malignant neoplasms?

Answer 6

• Differentiation is the degree to which a neoplasm histologically resembles its tissue of origin.
• Benign neoplasms is always well-differentiated.
• Malignant neoplasms have variable differentiation.

Question 7

What is the difference between staging and grading of neoplasms?

Answer 7

• Staging is used to measure the extent of spread.

- Grading is used to describe the degree of differentiation.

Question 8

Describe the naming system for benign and malignant neoplasms that originate from epithelial and mesenchymal tissues.

Answer 8

• The suffix for a benign neoplasm of squamous and transitional epithelial cells is papilloma.
• The suffix for a benign neoplasm of glandular epithelial cells is adenoma.
• The suffix for a malignant neoplasm of squamous and transitional epithelial cells is carcinoma.
• The suffix for a malignant neoplasm of glandular epithelial cells is adenocarcinoma.
• The suffix for a benign neoplasm of mesenchymal tissue is ‘-oma’
• The suffix for a malignant neoplasm of mesenchymal tissue is a sarcoma.

Question 9

Thyroid cancers have a different classification system to other cancers.

How are thyroid cancers classified?

List the categories of thyroid cancer in descending order of both frequency and prognosis.

Answer 9

• Thyroid cancers are classified on the basis of their histology. In descending order of both frequency and prognosis, classes include:

1 - Papillary.

2 - Follicular.

3 - Anaplastic.

Question 10

What is a teratoma?

Answer 10

• A teratoma is a neoplasm derived from embryonic germ cells.
• Teratomas have the capacity to form cells representative of all 3 germ cell layers (they are totipotent cells).

Question 11

List the sites at which teratomas occur.

State whether a teratoma occuring in each of these sites is usually benign or malignant.

Answer 11

Teratomas occur:

1 - In the ovary (usually benign).

2 - In the testis (usually malignant).

3 - In midline structures (behaviour variable).

Question 12

Define blastoma.

List 2 examples of blastomas.

Answer 12

• A blastoma is a neoplasm derived from multipotent embryonic blast cells.

1 - Wilms tumour (nephroblastoma).

2 - Hepatoblastoma.

Question 13

What are hamartomas?

List 2 examples of hamartomas.

Answer 13

• Hamartomas are tumour-like malformations (not genuine neoplasms).
• Hamartomas stop growing when the host stops growing.

1 - Pigmented nevi (moles).

2 - Skin haemangioma.

Question 14

List 5 differences in the gross appearance between benign and malignant neoplasms.

Answer 14

1 - Benign neoplasms are well circumscribed, whereas malignant neoplasms are irregular in shape.

2 - Benign neoplasms are smaller in size, whereas malignant neoplasms are larger.

3 - Benign neoplasms don’t usually haemorrhage, whereas malignant neoplasms commonly do.

4 - Benign neoplasms don’t usually form ulcers, whereas malignant neoplasms commonly do.

5 - Benign neoplasms don’t usually necrose, wheeas malignant neoplasms commonly do.

Question 15

Define pleomorphism.

Answer 15

• High variation in the size and shape of the cells and nuclei within a population of cancer cells.
• This is characteristic of malignant tumours.

Question 16

List 5 differences in the microscopic features between benign and malignant neoplasms.

Answer 16

1 - Benign neoplasms have a normal nuclear size, whereas malignant neoplasms have enlarged nuclei.

2 - Benign neoplasms have small nucleoli, whereas malignant neoplasms have prominent nucleoli (usually expressed in terms of nuclear:cytoplasmic ratio).

3 - Benign neoplasms don’t usually show pleomorphism, whereas malignant neoplasms commonly do.

4 - Benign neoplasms do not frequently undergo mitosis, whereas malignant neoplasms frequently undergo mitosis.

5 - Benign neoplasms are well differentiated, whereas malignant neoplasms have variable differentiation.

Question 17

What is a leiomyoma?

What are fibroids?

Answer 17

• A leiomyoma is benign neoplasm of smooth muscle.

- A fibroid is a neoplasm of smooth muscle of the uterus.

Question 18

What is a rhabdomyoma?

Answer 18

A benign neoplasm of striated muscle.

Question 19

List 2 differences in the growth characteristics between benign and malignant neoplasms.

Answer 19

1 - Benign neoplasms grow at a slow rate, whereas malignant neoplasms grow at a rapid rate.

2 - Benign neoplasms commonly undergo spontaneous arrest, whereas malignant neoplasms rarely undergo spontaneous arrest.

Question 20

How do benign neoplasms cause damage to the host?

Answer 20

Benign neoplasms cause damage to the host by exerting mechanical pressure.