Benign and malignant tumours and classification Flashcards
What can a tumour mean?
- Tumour - any abnormal swelling:
- Neoplasm
- Inflammation
- Hypertrophy
- Hyperplasia
What is a neoplasm?
- A lesion resulting from the autonomous or relatively autonomous abnormal growth of cells which persists after the initiating stimulus has been removed
- A new growth
What is the structure of a neoplasm?
- Neoplastic cells
- Stroma
What are features of neoplastic cells?
- Always derived from nucleated cells (need nucleus for growth)
- Usually monoclonal
- Growth pattern and synthetic activity related to parent cell (eg. if from thyroid, will grow like thyroid may even produce same hormone)
What are features of the stroma?
- Connective tissue framework
- Mechanical support and nutrition
- Usually not formed in haematopoietic neoplasms
What is tumour angiogenesis?
- Tumours growing a blood supply
- Determines size of neoplasm, can’t grow more than 2mm without
What can happen in tumour angiogenesis in malignant neoplasms?
- Central necrosis (cells dying in middle) due to malignant neoplasms growing faster than blood supply
What are 2 ways of classifying neoplasms?
- Behavioural
- Histogenetic
What are the categories of behavioural classification?
- Benign
- Borderline
- Malignant
What are features of benign neoplasms?
- Localised, non-invasive
- Slow growth rate
- Low mitotic activity
- Close resemblance to normal tissue
- Circumscribed or encapsulated (usually by rim of normal tissue)
What are histological features of benign neoplasms?
- Nuclear morphometry often normal
- Necrosis rare
- Ulceration rare
- Growth on mucosal surfaces usually exophytic (up and outwards)
What problems can benign neoplasms cause?
- Cause morbidity and mortality
- Pressure on adjacent structures
- Obstruct flow
- Produce hormones
- Transform to malignant neoplasm
- Anxiety
What are features of malignant neoplasms?
- Invasive
- Defining feature
- Metastases
- Rapid growth rate
- Variable resemblance to normal tissue
- Poorly defined or irregular border
What are histological features of malignant neoplasms?
- Hyperchromatic nuclei
- Darker than normal
- Pleomorphic nuclei
- Larger than normal
- Increased mitotic activity
- Necrosis and ulceration common
- Growth on mucosal surfaces and skin often endophytic (downwards and inwards)
What problems can malignant neoplasms cause?
- Cause morbidity and mortality
- Destruction of adjacent tissue
- Metastases
- Blood loss from ulcers
- Obstruct flow
- Produce hormones
- Paraneoplastic effects
- Effects at distant sites
- Anxiety and pain
What is histogenetic classification based on?
The specific cell of origin of a neoplasm
What types of cells can neoplasms arise from?
- Epithelial cells
- Connective tissues
- Lymphoid/haematopoietic organs