Neoplasia 1 Flashcards
Definitions
Tumour = a swelling (remember from inflammation!!!) Any clinically detectable lump or swelling
Neoplasm
What is dysplasia
Dysplasia is a pre-neoplastic alteration in which the cells show disordered tissue organisation (so can become or be malignant - can catch this before it develops and invades other tissue)
Reversible
Can exhibit considerable pleomorphism, with large hyperchromatic nuclei and high nuclear to cytoplasmic ratios
Primary vs secondary - The original location of the malignant neoplasm is the primary site
The place to which it has spread is the secondary site (there could be many secondary sites).
Benign vs Malignant
Essentially differences in Behaviour
Appear different to the naked eye (on palpation)
Differentiation
Benign neoplasms remain confined to their site of origin and do not produce metastases
Malignant neoplasms invade and have the potential to metastasise
Benign tumours - Grow in a confined local area, They have a pushing outer margin, Rarely dangerous (depends on location e.g. oesophagus)
Malignant tumours - irregular outer margin and shape, May have ulcerations and necrosis, Infiltrative (cross basement membrane)
Differentiation = the process of becoming different by growth or development
Benign neoplasms closely resemble the parent tissue - well differentiated
Malignant neoplasms range from well to poorly differentiated, (less likely to perform the same function that the cell you replaced did - can lead to lack of function in tissues and organs) dependent on how closely they resemble the cell of origin.
Cells with no resemblance to any tissue are called anaplastic
With worsening differentiation the individual cells have
Increasing nuclear size
Increased nuclear to cytoplasmic size
Increased nuclear staining (hyperchromasia)
Increased mitotic figures
Abnormal mitotic figures (Mercedes Benz)
Variation in size and shape of cells and nuclei (pleomorphism)
Clinicians use the term grade to indicated differentiation, a high grade tumour is usually poorly differentiated
Dysplasia
Altered differentiation
Mild, moderate and severe - worsening differentiation
From the picture on the right, you can see that even thought it seems to be getting worse, it hasn’t crossed the basement membrane therefore its still benign dysplasia not malignant
Why do we get neoplasia
Carcinogenesis
Non-lethal (non-cell destroying) genetic damage
Accumulated mutations in somatic cells - Mutations are caused by initiators
Which genes are affected?
There are four classes of normal regulatory genes:
Growth promoting proto-oncogenes
Growth inhibiting tumour suppressor genes
Genes that regulate programmed cell death (apoptosis)
Genes involved in DNA repair
These are the targets of cancer causing mutations - if a mutation occurs in 1 or more of these genes - then it causes cell cycle and apoptosis to be affected - therefore cell that should be killed isn’t killed and can keep on dividing to make defective daughter cells
4 classes of genes
Proto-Oncogenes
Multiple functions but all participate at some level in signalling pathways that drive proliferation
Mutations that activate these generally cause an excessive increase in one or more normal functions
Sometimes they impart a completely new function on the affected gene - ‘Gain-of-fu
Neoplasms
Naming - Confusing mixture of an organised system that follows rules and a traditional system that disobeys them Takes into account: The neoplasms site of origin Benign or malignant Sometimes the gross morphology In general: Benign tumours end in
Connective tissue neoplasms
Benign - Smooth muscle - Leiomyoma Fibrous tissue - Fibroma Bone - Osteoma Cartilage - Chondroma Fat - Lipoma Nerve - Neuroma
Malignant - Smooth muscle - Leiomyosarcoma Fibrous tissue - Fribosarcoma Bone - Osteosarcoma Cartilage - Chondrosarcoma Fat - Liposarcoma
