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
What are the 2 types of benign epithelial neoplasms?
Secretory (glandular) and non-secretory epithelium (non-glandular)
What is a neoplasm of a benign (non-glandular) non-secretory epithelium?
Papilloma
Prefix with cell type of origin, e.g. squamous cell papilloma
What is a neoplasm of (glandular) secretory epithelium?
Adenoma
Prefix with cell type of origin, e.g. colonic adenoma, thyroid adenoma
What are malignant neoplasms of epithelial cells called?
Carcinoma
- Prefix with epithelial cell type e.g. urothelial carcinoma
What are carcinomas of glandular epithelium called?
Adenocarcinomas
What are benign connective tissue neoplasms called?
Named according to cell type of origin, suffixed by ‘-oma’
What is a lipoma?
benign connective tissue neoplasm of adipocytes
