L18 - Characteristic of tumours Flashcards
What is the definition of ‘differentiation’ in terms of tumours?
The extent that neoplastic cells resemble the corresponding normal parenchymal cells, morphologically and functionally
What are the characteristics of benign tumours in terms of differentiation?
- usually well-differentiated
- mitoses are rare
What are the characteristics of malignant neoplasms in terms of differentiation?
- wide range of parenchymal differentiation
- most exhibit morphologic alterations showing malignant nature
What is anaplasia?
Poorly-differentiated cells
A condition whereby cells lose the morphological characteristics of mature cells
How are neoplasms comprised of poorly-differentiated cells described?
Anaplastic
What condition is a “telltale sign of malignancy”
Anaplasia
Neoplasms comprised of poorly-differentiated cells
What are some possible morphological changes in cells?
- pleomorphism
- abnormal nuclear morphology
- mitoses
- loss of polarity
- other changes
What is pleomorphism?
Describes variability in the size, shape and staining of cells and/or their nuclei
Give some examples of the huge differences shown in pleomorphism
- small cells with little differentiation
- large cells with one massive nucleus
- large cells with multinucleation
Cells can have abnormal nuclear morphology. Give some examples of this
- nuclei appear too large for the cell
- variability in nuclear shape
- chromatin distribution
- hyperchromatism
- abnormally large nucleoli
In abnormal nuclear morphology, there can be hyperchromatism. What does this look like?
Dark colour
What are mitoses an indication of and what are they seen in?
An indication of proliferation
Therefore seen in normal tissues with a rapid turnover and in hyperplasias
In malignancy, atypical bizzare mitotic figures are seen. Give examples
- tripolar division
- quadripolar division
- multiple spindles
etc
What occurs in loss of polarity in cells?
- orientation of cells disturbed
- disorganised growth
what are characteristics of well differentiated tissues?
- closely resembles normal tissue or origin
- little or no evidence of anaplasia
- benign and occasional malignant
what are the main characteristics of poorly differentiated tissues?
- little resemblance to tissue of origin
- highly anaplastic appearance
what are characteristics of undifferentiated/anaplastic tissues?
- cannot be identified by morphology alone
- need molecular techniques
what does a low grade refer to?
well differentiated = low grade/grade 1
moderately differentiate = intermediate/grade 2
poorly differentiated = high grade/grade 3
What is ‘stage’ in terms of classification of tumours?
A measure of extent of disease [How far the tumour goes]
Better differentiation = ?
Better retention of normal function
How can benign and well-differentiated carcinomas of the endocrine glands be detected?
They frequently secrete hormones characteristic of origin
Increased levels in the blood can be used to detect and to follow up tumours
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 benign tumours, what are the characteristics of the tissue plane?
- discrete, moveable
- easily palpable
- easily excised
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?
No
Penetration of organ surfaces and skin
Is surgical resection easy in malignant tumours?
No
Requires resection of adjacent macroscopically normal tissue (margin)
What is metastasis?
Spread of a tumour to sites physically discontinuous with the primary tumour
What are the 3 pathways for metastasis?
- direct seeding
- lymphatic spread
- haematogenous spread
What is direct seeding?
The neoplasm penetrates a natural open field without physical barriers
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?
Lymphatic spread
Describe lymphatic spread
- lymphatic vessels at the tumour margins
- pattern of lymph node involvement follows the routes of lymphatic drainage
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?
Liver (portal)
Lungs (caval)
In haemotogenous spread, why are veins involved?
They are more easily penetrated because they have thinner walls
What is the stroma?
Connective tissue framework that neoplastic cells are embedded in
What does the stroma provide?
- mechanical support
- intercellular signalling
- nutrition
What is a desmoplastic reaction?
Fibrous stroma formation due to induction of connective tissue fibroblast proliferation by growth factors from the tumour cells
What does the stroma contain? (in a desmoplastic reaction)
- cancer-associated fibroblasts
- myofibroblasts (see puckering of skin)
- blood vessels (blood to tumour)
- lymphatics
What are the clinical complications of tumours dependent on?
- location
- cell of origin
- behaviour
In what general classifications can effects of tumours be?
- local
- metabolic
- due to metastases
What are some LOCAL complications of tumours?
- compression
- destruction
Compression is a local complication of tumours. Describe this
Displacement of adjacent tissue
- benign eg. pituitary adenomas obliterate adjacent functioning pituitary tissue leading to hypopituitarism
Destruction is a local complication of tumours. Describe this
Invasion
Rapidly fatal is vital structures are invaded e.g. artery
Mucosal surfaces - ulceration eg. GI - anaemia
Give some non-specific METABOLIC complications of tumours
- cachexia
- warburg effect
- neuropathies
- myopathies
- venous thrombosis
What is cachexia?
Profound weight-loss despite apparently adequate nutrition
Tumour-derived humoral effects that interfere with protein metabolism
what does a low grade refer to?
Poorly differentiated = high grade / grade 3
what is the definition of cancer?
The uncontrolled growth of cells, which can invade and spread to distant sites of the body
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
what is histogenesis?
The differentiation of cells into specialised tissues and organs during growth from undifferentiated
cells
what are the most common cancers in males?
lung; colon and rectum; prostate
lung most common
what are the most common cancers in females?
lung; colon and rectum; breast
lung most common
what is the definition of differentiation?
The extent that neoplastic cells resemble the corresponding normal parenchymal cells, morphologically and functionally
how do you definite the rate of growth? (in relation to malignancy)
Doubling time of tumour cells; Fraction of tumour cell in replicative pool; Rate at which cells are shed or die
