L18- Characteristics of Tumours

Question 1

What is Cancer?

Answer 1

Cancer is the uncontrolled growth of cells, which can invade and spread to distant sites of the body

Question 2

What is a tumour?

Answer 2

Historically – an abnormal swelling

Synonymous with Neoplasm

Question 3

What is a Neoplasm?

Answer 3

Lesion resulting from the autonomous growth or relatively autonomous abnormal growth of cells that persists in the absence of the initiating stimulus

(abnormal growth of tissue, and when also forming a mass is commonly referred to as a tumor or tumour….This abnormal growth (neoplasia) usually but not always forms a mass)

Question 4

What is Histiogenesis

Answer 4

The differentiation of cells into specialised tissues and organs during growth from undifferentiated cells (the 3 primary germ layers)

Question 5

Tumours are usually named in relation to where they are found: Epithelial cells

Answer 5

carcinomas

Question 6

Tumours are usually named in relation to where they are found: Connective tissues

Answer 6

sarcomas

Question 7

Tumours are usually named in relation to where they are found: Lymphoid/haematopoietic organs

Answer 7

lymphomas/leukaemias

Question 8

What are tumours characterised by?…(3 things)

Answer 8

Differentiation
Rate of Growth
Local Invasion
Metastasis

Question 9

Do Malignant tumours tend to grow more rapidly than benign tumours?

Answer 9

Many exceptions to this rule
Not useful to discriminate

Different malignancies show varied growth rates
◦ Slow growing tumours associated with long survival
◦ Rapidly-growing tumours lethal within a short time

Question 10

Define Differentiation in terms of tumours

Answer 10

The extent that neoplastic cells resemble the corresponding normal parenchymal cells, morphologically and functionally

Question 11

Comment on the differentiation between Benign and malignant tumours…

Answer 11

Benign tumours
◦ usually well-differentiated
◦ Mitoses are rare

Malignant neoplasms
◦ wide-range of parenchymal differentiation
◦ Most exhibit morphologic alterations showing malignant nature

Question 12

What is Anaplasia?

Answer 12

Lack of differentiation in neoplastic cells

Well-differentiated tumors resemble their tissue of origin

poorly-differentiated or undifferentiated (anaplastic) tumor cells appear primitive and lack specialisation

(Tell tale sign of Malignancy)

Question 13

What is Pleomorphism?

Answer 13

variability in the size, shape and staining of cells and/or their nuclei

Variation
◦ Size
◦ shape

Question 14

Explain how you can differentiate Abnormal nuclei Morphology?

Answer 14

Nuclei appear too large for the cell that they are in

Variability in nuclear shape (irregular e.g look like faces)

Hyperchromatism (dark colour)

Abnormally large nucleoli

Question 15

What are mitoses

Answer 15

Represent the chromosomes all lined up in metaphase
come up as long dark blobs when stained
An indication of proliferation

Atypical, bizarre mitotic figures seen in malignancy:
◦ Tripolar
◦ Quadripolar
◦ Multipolar spindles

Question 16

Summary of Differentiation: Meaning of Well differentiated

Answer 16

◦ Closely resembles normal tissue of origin
◦ Little or no of evidence of anaplasia
◦ BENIGN and occasional malignant

Question 17

Summary of Differentiation: Meaning of Moderately differentiated

Answer 17

◦ Somewhere in between

Question 18

Summary of Differentiation: Poorly differentiated

Answer 18

◦ Little resemblance to tissue of origin

◦ Highly anaplastic appearance

Question 19

Summary of Differentiation: Undifferentiated / anaplastic

Answer 19

◦ Cannot be identified by morphology alone

◦ Molecular techniques

Question 20

Grades are related to differentiation, talk about the different grades…1, 2, 3

Answer 20

◦ Well differentiated = low grade / grade 1

◦ Moderately differentiated = intermediate / grade 2

◦ Poorly differentiated = high grade / grade 3

Question 21

Changes in function can occur in Tumours of cells: What are the clinical clues?

Answer 21

e.g Can secret excess hormones
Increased levels in blood can be used to detect and to follow up tumours

Some express proteins only normally found in other adult cells

Some tumours express foetal proteins not seen in adults

Question 22

Why are malignant local invasions difficult to treat?

Answer 22

Penetration of organ surfaces and skin

Surgical resection difficult

Requires resection of adjacent macroscopically normal tissue (margin)

Question 23

What is Metastasis

Answer 23

Spread of a tumour to sites physically discontinuous with the primary tumour

Reduces life expectancy significantly

Question 24

Metastasis is generally associated with..

Answer 24

◦ Lack of differentiation
◦ Local invasion
◦ Rapid growth
◦ Large size

Question 25

Pathways of Metastasis: What is Direct seeding…

Answer 25

when cancer cells break away from the original tumor and seed in body cavities (such as the pleural cavity of the chest or peritoneal cavity of the abdomen)

Question 26

Pathways of Metastasis: What is Lymphatic spread…

Answer 26

◦ Most common pathway
◦ Tumours do not contain lymphatic channels
◦ Lymphatic vessels at the tumour margins

Question 27

Example of Lymphatic spread Metastasis

Answer 27

Example – Breast
Most commonly presents in upper outer quadrant

Disseminate first to axillary nodes

Then infraclavicular and supraclavicular nodes become involved

Question 28

What is a sentinel node?

Answer 28

The first node in a regional lymphatic basin that receives lymph flow from the primary tumour

Identified by:
◦ Injection of radiolabelled tracers/coloured dyes

Question 29

How do Metastasis spread Haematogenously?

Answer 29

Veins more easily penetrated = thinner walls

Bloodborne cells follow the venous flow draining site of the neoplasm = then end up in a capillary bed (E.g Liver - portal system and Lungs- Caval system)

Question 30

What is stroma and what does it provide?

Answer 30

Connective tissue framework that neoplastic cells are embedded in

Provides:
◦ Mechanical support
◦ Intercellular signalling
◦ Nutrition

Question 31

What does stroma contain that makes it carcinogenic?

Answer 31

◦ Cancer-associated fibroblasts
◦ Myofibroblasts
◦ Blood vessels
◦ Lymphocytic infiltrate