Characteristics of tumours Flashcards
Define cancer
Uncontrolled growth of cells which can invade and spread to distant sites of the body
Define neoplasm
Lesion resulting from the autonomous (abnormal) growth of cells that persists in the absence of the initiating stimulus
Define histogenesis
Differentiation of cells into specialised tissues/organs during growth from undifferentiated cells
What are the classifications of histogenic cancers?
- Epithelial cells= Carcinomas
- Connective tissues= Sarcomas
- Lymphoid/haeatopoietic organs= lymphomas/leukaemias
How are tumours characterised?
- Differentiation
- Rate of growth
- Local invasion
- Metastasis
Define differentiation in terms of cancer cells and link this to benign tumours & malignant neoplasms
Extent that neoplastic cells resemble the corresponding normal parenchymal cells, functionally & morphological
B-Well differentiated, mitoses rare
M-Anaplastic (poor differentiation), wide range of differentiation, most exhibit morphologic alterations
What morphological changes can be observed in differentiation?
- Pleomorphism
- Abnormal nuclear morphology
- Mitoses
- Loss of polarity
What is pleomorphism?
- Variation in size/shape
- Large cells multinucleated
- Large cells w/one huge nucleus
What is abnormal nuclear morphology?
- Nuclei appear too large for the cell
- Nuclear to cytoplasmic ratio is 1:1 rather than 1:4or6
- Variability in nuclear shape= irregular or ‘making pictures’
- Chromatic distribution coarsley clumped & along cell membrane
- Hyperchromatism
- Abnormally large nucleoli
What is different about mitoses in cancer?
- Tripolar/quadripolar/multipolar spindles
- Indication of proliferation
- Usually seen in tissue with rapid turnover
What is loss of polarity?
- Disorganised growth
- Orientation of cells is disturbed
What does grade mean when talking about tumours?
- Closely related to differentiation
- GRADE1= Well differentiated
- GRADE2= moderately differentiated
- GRADE3= poorly differentiated
What does stage mean when referring to tumours?
-Measure of prognosis/therapeutic decision
What changes in function can occur in tumour cells?
- Some tumours express foetal proteins not seen in adults
- Some express proteins only normally found in other adult cells
- Benign & well-differentiated carcinomas usually secrete hormones characteristic of origin
What are examples of paraneoplastic syndromes?
- Bronchogenic carcinoma
- Insulin
- Glucagon
- Parathyroid-like hormone
- Corticotropin
What is characteristic of local invasion by a benign or cancerous tumour?
B- cohesive mass, localised to site of origin, no capacity to infiltrate/invade, encapsulated (rim of compressed fibrous tissue, ECM deposited by stroma cells)
C-invasion, destruction, infiltration, pseudoencapsulation (slow growing rows of cells penetrating margin)
What are pathways of metastasis? Describe them
- Direct seeding=Neoplasm penetrates a natural open field without physical barriers (peritoneal cavity) can remain confined
- Lymphatic spread= most common, lymph node involvement follows rout of lymphatic drainage, determination of axillary node status determines future course of disease & therapy
- Haematogenous spread= typically sarcomas, veins more easily penetrated as thinner walls, blood borne cells follow venous flow draining site of the neoplasm
What are sentinel nodes?
- First node in a regional lymphatic basin that receive lymphatic flow from the primary tumour
- Identified by injection of coloured dye
Why are regional nodes used?
- Effective barriers to further tumour dissemination
- Cells arrest within node and can then be destroyed by tumour specific immune response
Define stroma and what it provides
- Connective tissue framework that neoplastic cells are embedded in
- Provides mechanical support, nutrition, intercellular signalling
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?
- Cancer associated fibroblasts
- Blood vessels
- Myofibroblasts
- Lymphatic infiltrate
What are local complications of tumours?
-Compression: Displacement of adjacent tissues -Destruction: Invasion Rapidly fatal if vital structures invaded (artery) Mucosal surfaces (ulceration)
What are metabolic complications of tumours/
- Tumour type specific
- Number of cells exceeds normal organ
- Autonomous
- Cachexia (weight loss)
- Warburg effect (produces energy by high rate of glycolysis w/fermentation of lactic acid can be used in PET scanning)
- Myopathies
- Neuropathies
- Venous thrombosis
