Characteristics of Tumours Flashcards
Define neoplasm?
Lesion resulting from the autonomous growth or relatively autonomous abnormal growth of cells that persists in the absence of the initiating stimulus
Define histogenesis?
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?
Carcinomas
Tumours arising from connective tissues are known as what?
Sarcomas
Tumours arising from lymphoid/haematopoietic organs are known as what?
Lymphomas/leukaemias
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?
1) Prostate
2) Lung
3) Colon and rectum
What are the 3 most common cancers in females?
1) Breast
2) Lung
3) Colon and rectum
What 4 factors enable you to distinguish between benign and malignant tumours?
1) Differentiation
2) Rate of growth
3) Local invasion
4) Metastasis
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?
1) Pleomorphism
2) Abnormal nuclear morphology
3) Mitoses
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