0602 - Introduction to Neoplasia

Question 1

Define and explain the term Neoplasm

Answer 1

Neoplasm – ‘new growth’. A persistent clonal proliferation of cells due to the accumulation of somatic genetic injuries.

The mass is purposeless, preys on the host, and is virtually autonomous.

Question 2

Define and explain the term Tumour

Answer 2

Tumour – ‘swelling’. Though commonly used as a synonym for neoplasm, it can be non-neoplastic such as caused by inflammation or infection.

Question 3

Define and explain the term Oncogenesis

Answer 3

Oncogenesis – the process of forming a tumour. Generally confined to malignant neoplasms, but in reality a much broader term.

Question 4

Define and explain the term Benign

Answer 4

Benign – ‘good natured’. A neoplasm that does not metastasise. Happy to stay in place.

This does NOT mean harmless.

Question 5

Define and explain the term Malignant

Answer 5

Malignant – ‘very bad’. A neoplasm that metastasises and has become cancerous.

Question 6

Define and explain the term Differentiation

Answer 6

Differentiation – The extent to which neoplastic cells resemble a normal counterpart (morphologically, cytologically, architecturally and functionally).

Question 7

Define and explain the term anaplasia.

Answer 7

Anaplasia – The loss of normal cell characteristics or differentiation, possibly to the extent that the cell origin cannot be defined. Typical of fast growing, malignant tumours.

Question 8

Define and explain the term dysplasia

Answer 8

A premalignant condition that involves the abnormal growth of tissue cells.

Question 9

What are the four key characteristics that can differentiate between malignant and benign neoplasms? Which is the most important?

Answer 9

Structure (microscopically)
Rate of growth over time
Invasive growth
Disseminated growth (metastasis).

Metastasis is the only one that is unique to neoplasms.

Question 10

What aspects of structure would a pathologist examine in order to ascertain whether a neoplasm is malignant?

Answer 10

Cellular pleomorphism (variable cell size and shape)
Nuclear pleopmorphism (variable nuclear size and shape)
Increased nuclear-cytoplasmic ratio (normal is 1:4-1:6 – may approach 1:1)
Hyperchromatic nuclei (increased DNA attracting stain)
Increased or abnormal mitosis
Tumour giant cells (massive, often multinucleated)

Question 11

What aspects of growth rate could be examined in order to ascertain whether a neoplasm is malignant?

Answer 11

Benign = slow growing, malignant = fast growing (except growth of leiomyoma in pregnancy)
Does the rate of growth correlate with the blood supply and differentiation?
Is there central necrosis that may indicate the neoplasm has outgrown its blood supply (suggesting malignancy)?

Question 12

How can the presence or absence of invasion help ascertain whether a neoplasm is malignant?

Answer 12

Invasion is a reliable feature of malignancy. Normally, benign neoplasms will have capsules however this is not always the case. The presence of a capsule would need to be confirmed, as microscopic invasion can occur.

Malignant cells may create a ‘desmoplastic stroma’ of collagen, blood etc to nourish them. Benign cells are sufficiently slow-growing that they don’t need it.

Question 13

How can the presence or absence of metastasis help ascertain whether a neoplasm is malignant?

Answer 13

Metastasis is a neoplasm implant discontinuous from the primary neoplasm. It is an unequivocal sign of malignancy. Pathways include:
Seeding via body cavities
Lymphatic spread
Haematogenous spread.

Question 14

Explain the nomenclature of neoplasms

Answer 14

Names are based on cell of origin and nature of the neoplasm.

Work from the end backwards:
-Oma = neoplasm
Define tissue of origin - Carcin/Sarco/Melan/lymph-oma = malignant neoplasm of epithelial/mesenchymal/melanitic/lymphatic origin (others such as fibroma, adenoma are generally benign)
Give specific tissue type (e.g. basal cell carcinoma, leiomyoma).