Flashcards in 18. Characteristic of tumours Deck (72)
Can benign tumours invade other areas of the body?
No, they are localised to their site of origin and cannot infiltrate, invade or metastasise
What is encapsulation? (in terms of benign tumours)
The tumour grows in a contained area usually surrounded by a fibrous connective tissue capsule
In encapsulation of benign tumours, ECM is deposited by stromal cells. How is this activated?
Activated by hypoxia from the pressure of the tumour
In benign tumours, what are the characteristics of the tissue plane?
Easy to identify because they are
- discrete, moveable
- easily palpable
- easily excised
The fibrous capsule around benign tumours consists of extracellular matrix (ECM). What is ECM deposited by?
This process is activated by hypoxia from pressure of the tumour
Whereas you get encapsulation of benign tumours, what can sometimes occur in malignant tumours?
Happens in the more slow-growing tumours
What is pseudoencapsulation?
Happens in slow-growing malignant tumours
Looks like encapsulation but microscopically there are actually rows of cells penetrating the margin
Do malignant tumours respect anatomical boundaries?
Penetration of organ surfaces and skin
Is surgical resection easy in malignant tumours?
Requires resection of adjacent macroscopically normal tissue (margin)
What is metastasis?
Spread of a tumour to sites physically discontinuous with the primary tumour
What does pathognomic mean?
Characteristic of a particular disease
What is metastasis pathognomic of?
If a tumour metastasises, it is NOT benign
What proportion of cancers metastasise?
30% of non-skin malignancies have metastasised at diagnosis
Metastasis is generally correlated which what features? (but with lots of exceptions)
- lack of differentiation
- local invasion
- rapid growth
- large size
What are the possible pathways for metastasis?
- direct seeding
- lymphatic spread
- haematogenous spread
What is direct seeding? (a pathway for metastasis)
The neoplasm penetrates a natural open field without physical barriers
Can remain confined to surface of peritoneal structures without penetrating eg. pseudomyxoma peritonea
In direct seeding, a neoplasm penetrates a natural open field without physical barriers. Give some examples of these
- peritoneal cavity
- pleural cavity
- pericardial space
- subarachnoid space
- joint spaces
What is the most common pathway for metastasis?
Describe lymphatic spread
- tumours do not contain lymphatic channels
- lymphatic vessels at the tumour margins
- pattern of lymph node involvement follows the routes of lymphatic drainage
What is the pattern of lymphatic spread in breast cancers?
- most commonly presents in upper outer quadrant
- disseminate first to axillary nodes
- then infraclavicular and supraclavicular nodes become involved
What determines future course of disease and what therapy is most suitable for a patient with breast cancer?
Determination of axillary node status
What are sentinel nodes?
The first node in a regional lymphatic basin that receives lymph flow from the primary tumour
(the first few lymph nodes into which a tumour drains)
How are sentinel nodes identified?
Injection of radiolabelled tracers/coloured dyes
Despite being a passage of spread for tumours, how can regional nodes be beneficial?
Effective barriers to further tumour dissemination
Cells arrest within node and then can be destroyed by a tumour-specific immune response
Does every enlarged node next to a tumour have cancer in it?
Drainage of tumour cell debris and tumour antigens induces a reactive change in nodes
What is haematogenous spread seen in?
Typical of sarcomas
But also seen in carcinomas!
Describe haematogenous spread
Bloodborne cells follow the venous flow drainage site of the neoplasm
Often come to rest in the first encountered capillary bed
In haematogneous spread, the cells often come to rest in the first encountered capillary bed, what is most frequently involved?
In haemotogenous spread, why are veins involved?
They are more easily penetrated because they have thinner walls