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Flashcards in Characteristics of tumours Deck (27):
1

What is histiogenesis?

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

2

What is histiogenesis relating to tumours?

Histogenic classification – classification of the tumour by the specific cell or tissue of origin
- Epithelial cells – carcinomas
- Connective tissues – sarcomas
- Lymphoid/haematopoietic organs – lymphomas/leukaemias

3

What is differentiation?

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

4

What are the characteristics of differentiation of benign tunours?

- usually well-differentiated
- Mitoses are rare

5

What are the differentiation characteristics of malignant tumours?

-Wide-range of parenchymal differentiation
-Most exhibit morphologic alterations showing malignant nature

6

What is anaplasia?

Neoplasms comprised of poorly-differentiated cells are described as anaplastic
“Telltale sign of malignancy”

7

What are the morphological changes that might occur during neoplasia?

- Pleomorphism
- Abnormal nuclear morphology
- Mitoses
- Loss of polarity
- Other changes

8

What is pleomorphism?

Variation - Size, shape
Huge differences
- Small cells with little differentiation
- Large cells with one massive nucleus
- Large cells with multinucleation

9

What abnormal nuclear morphology might be seen in cancer?

Nuclei appear too large for the cell that they are in
Nuclear to cytoplasmic ratio
-Can reach 1:1 rather than usual (1:4 or 1:6)
Variability in nuclear shape
-Irregular
-Making pictures (raisins, faces etc.)
Chromatin distribution
-Coarsely clumped
-Along cell membrane
Hyperchromatism
-Dark colour
Abnormally large nucleoli

10

What are mitoses?

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

11

What are the features of loss of polarity?

- Orientation of cells disturbed
- Disorganised growth

12

What is the grade of a tumour related to?

Closely related to differentiation / clinical behaviour

Well differentiated = low grade / grade 1
Moderately differentiated = intermediate / grade 2
Poorly differentiated = high grade / grade 3

13

What is the stage of a tumour related to?

How far the cancer has spread throughout the body.

14

How is the level of differentiation within a tumour related to a possible change in function?

The better the differentiation of the tumour the better the retention of function i.e. a large, benign endocrine tumour may secrete large amounts of hormone.

15

What kinds of local invasion are associated with malignancies?

-Infiltration
-Invasion
-Destruction

16

What kinds of local invasion are associated with benign neoplasia?

-Cohesive expansile masses
-Localised to site of origin
-No capacity to infiltrate, invade or metastasise

17

What histological features might represent local invasion of a benign tumour?

- Rim of compressed fibrous tissue
- ECM deposited by stromal cells activated by hypoxia from pressure of tumour
- Tissue plane
- Discrete, moveable
- Easily palpable
- Easily excised

18

What are metastases?

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

19

What are the pathways by which metastases can occur?

- Direct seeding
- Lymphatic spread
- Haematogenous spread

20

What is direct seeding?

Neoplasm penetrates a natural open field without physical barriers
Eg peritoneal cavity, pleural, pericardial, subarachnoid, joint spaces

Can remain confined to surface of peritoneal structures without penetrating
Eg pseudomyxoma peritonei

21

What is lymphatic spread?

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

22

What are sentinal nodes?

The first node in a regional lymphatic basin that receives lymph flow from the primary tumour
Identified by: injection of radiolabelled tracers/coloured dyes

23

Why might an enlarged node in a cancer patient not have cancer in it?

Drainage of tumour cell debris and tumour antigens induces reactive change in nodes

24

What are the features of haematogenous spread?

- Typical of sarcomas
- Also seen in carcinomas
- Veins more easily penetrated
- Blood-borne cells follow the venous flow draining site of the neoplasm
- Often come to rest in first encountered capillary bed
- Liver (portal) and lungs (caval) most frequently involved

25

What is the desmoplastic reaction?

Fibrous stroma formation due to induction of connective tissue fibroblast proliferation by growth factors from the tumour cells

Stroma contains:
Cancer-associated fibroblasts
Myofibroblasts
Blood vessels
Lymphocytic infiltrate

26

Why might a malignant tumour cause cachexia?

Tumour-derived humoral effects that interfere with protein metabolism.

27

What is the Warburg effect?

Cancer cells produce energy by high rate of glycolysis with fermentation of lactic acid
Used in imaging – PET scanning (FDG uptake)