Flashcards in Characteristics of Tumours Deck (52)
Lesion resulting from the autonomous growth or relatively autonomous abnormal growth of cells that persists in the absence of the initiating stimulus
The differentiation of cells into specialised tissues and organs during growth from undifferentiated cells (the 3 primary germ layers)
Tumours arising from epithelial cells are known as what?
Tumours arising from connective tissues are known as what?
Tumours arising from lymphoid/haematopoietic organs are known as what?
What 2 factors contribute to the geographic variation in specific cancers?
1) Exposure to environmental carcinogens
2) Screening programmes
What has been the pattern of cancer incidence from 1975-2009?
Was increasing and has begun to plateau
What has been the pattern in mortality from cancers from the 70's to now?
Decrease in mortality from cancer, however it is still one of the leading causes of death
What are the 3 most common cancers in males?
3) Colon and rectum
What are the 3 most common cancers in females?
3) Colon and rectum
What 4 factors enable you to distinguish between benign and malignant tumours?
2) Rate of growth
3) Local invasion
What is meant by the differentiation of a tumour?
The extent to which neoplastic cells resemble the corresponding normal parenchymal cells, morphologically and functionally
Are benign tumours usually well-differentiated or not?
Benign tumours are usually well differentiated and mitoses are rare
Are malignant tumours usually well or poorly differentiated?
Malignant neoplasms exhibit a wide range of parenchymal differentiation, most exhibit morphological alterations showing malignant nature
What is meant by anaplastic tumours?
Neoplasms consisting of poorly differentiated cells are described as anaplastic, this is a tell tale sign of malignancy
What is meant by pleomorphism?
Made up of cells which vary in shape and size
What 4 morphological changes can be seen in malignant tumours?
2) Abnormal nuclear morphology
4) Loss of polarity
What 4 changes can be seen in the cells of a malignant tumour showing abnormal nuclear morphology?
1) Nuclei appear too large for the cell that they are in: nuclear to cytoplasmic ratio can reach 1:1 rather than the usual 1:4/6
2) Variability in nuclear shape: irregular, 'making pictures'
3) Chromatin distribution: coarsely clumped, along cell membrane
4) Hyperchromatism: dark colour
5) Abnormally large nucleoli
Mitoses can be seen in the cells of malignant tumours, what is meant by this?
An indication of proliferation. Therefore seen in normal tissues with a rapid turnover and in hyperplasia. Atypical, bizarre mitotic figures seen in malignancy (tripolar, quadripolar, multipolar spindles)
What is meant by loss of polarity of cells of malignant tumours?
The orientation of cells is disturbed and you get disordered growth
What are the features of well differentiated tumours?
1) Closely resembles the normal tissue of origin
2) Little or no evidence of anaplasia
3) Benign and occasionally malignant
What are the features of poorly differentiated tumours?
Bear little resemblance to the tissue of origin, highly anaplastic appearance
What are the features of undifferentiated/anaplastic tumours?
Cannot be identified by morphology alone, have to use molecular techniques
How are grades applied to tumours according to their differentiation?
Well differentiated = low grade/grade 1
Moderately differentiated = intermediate/grade 2
Poorly differentiated = high grade/grade 3
How does the extent of differentiation affect function?
Better differentiation = better retention of normal function
What kind of tumours of endocrine glands display retention of function and how can this be useful in treatment?
Benign and well differentiated carcinomas of endocrine glands frequently secrete hormones characteristic of origin, increased levels in the blood can be used to detect and follow up tumours
Aswell as producing products of the tissue of origin, what other products can be produced by tumours which provide clinical clues?
Some tumours express foetal proteins not seen in adults
Some tumours express proteins only normally found in other adult cells
What is meant by paraneoplastic syndromes?
Syndromes that occur alongside the cancer
What is the difference in local invasion between a malignant tumour and a benign tumour?
Malignant tumour - infiltrates, invades and destroys local tissue
Benign tumour - appears as a cohesive, expansile mass, localised to sight of origin, no capacity to infiltrate, invade or metastasise