L18- Characteristics of Tumours Flashcards Preview

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Flashcards in L18- Characteristics of Tumours Deck (31):
1

What is Cancer?

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

2

What is a tumour?

Historically – an abnormal swelling

Synonymous with Neoplasm

3

What is a Neoplasm?

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)

4

What is Histiogenesis

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

5

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

carcinomas

6

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

sarcomas

7

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

lymphomas/leukaemias

8

What are tumours characterised by?...(3 things)

Differentiation
Rate of Growth
Local Invasion
Metastasis

9

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

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

10

Define Differentiation in terms of tumours

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

11

Comment on the differentiation between Benign and malignant tumours...

Benign tumours
◦ usually well-differentiated
◦ Mitoses are rare

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

12

What is Anaplasia?

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)

13

What is Pleomorphism?

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


Variation
◦ Size
◦ shape

14

Explain how you can differentiate Abnormal nuclei Morphology?

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

15

What are mitoses

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

16

Summary of Differentiation: Meaning of Well differentiated

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

17

Summary of Differentiation: Meaning of Moderately differentiated

◦ Somewhere in between

18

Summary of Differentiation: Poorly differentiated

◦ Little resemblance to tissue of origin
◦ Highly anaplastic appearance

19

Summary of Differentiation: Undifferentiated / anaplastic

◦ Cannot be identified by morphology alone
◦ Molecular techniques

20

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

◦ Well differentiated = low grade / grade 1

◦ Moderately differentiated = intermediate / grade 2

◦ Poorly differentiated = high grade / grade 3

21

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

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

22

Why are malignant local invasions difficult to treat?

Penetration of organ surfaces and skin

Surgical resection difficult

Requires resection of adjacent macroscopically normal tissue (margin)

23

What is Metastasis

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

Reduces life expectancy significantly

24

Metastasis is generally associated with..

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

25

Pathways of Metastasis: What is Direct seeding...

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)

26

Pathways of Metastasis: What is Lymphatic spread...

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

27

Example of Lymphatic spread Metastasis

Example – Breast
Most commonly presents in upper outer quadrant

Disseminate first to axillary nodes

Then infraclavicular and supraclavicular nodes become involved

28

What is a sentinel node?

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

Identified by:
◦ Injection of radiolabelled tracers/coloured dyes

29

How do Metastasis spread Haematogenously?

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)

30

What is stroma and what does it provide?

Connective tissue framework that neoplastic cells are embedded in

Provides:
◦ Mechanical support
◦ Intercellular signalling
◦ Nutrition

31

What does stroma contain that makes it carcinogenic?

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