Session 8 - Neoplasia 1 Flashcards
What is a neoplasm?
An abnormal growth of cells that continues to grow even after the initial stimulus is removed.
What is a malignant neoplasm?
This is a neoplasm that invades the surrounding tissue and has the potential to spread to distant sites (ie. undergo metastases).
What is a tumour?
Any kind of detectable lump or swelling. A neoplasm is just a TYPE of tumour.
What is dysplasia?
This is a pre-neoplastic state in which cells have undergone changes and show tissue disorganisation. It is a reversible process.
What is an anaplastic tissue?
A tissue that contains cells that have no comparitive phenotype to any other kind of cell (they look nothing like any kind of cell).
What changes do you start to see in worsening differentiated cells?
- Pleiomorphism: increasing variation in shape and size of the cells
- Increased nuclear to cytoplasmic ratio
- Mitotic figures
- Increased nuclear staining (hyperchromasia)
In terms of neoplasia, what does a grade measure?
This measures the level of differentiation that has occurred in a cell - ie. a high grade is a poorly differentiated cell.
What is neoplasia caused by?
Accumulated mutations in the somatic cell.
In terms of neoplasia what is an initiator? What does a promoter cause?
This is the mutagen which initiates the mutation. A promoter than causes cell proliferation.
How do we know that neoplasms are monoclonal?
This is due to research that has been carried out into the X linked allele coding for G6PD. This gene has many different alleles coding for isoenzymes - early in female embryogenesis one of these alleles is inactivated in each cell (lyonisation).
The two different alleles are heat labile and heat stable - so normally in heterozygous women they will have a patchwork of cells expressing each type.
However in neoplasia only one of the enzymes works indicating a monoclonal population of cells.
Carcinomas can be in-situ or invasive. What is the difference between the two of these?
In-situ means that it sits within the borders of the space and does not invade the basement membrane. Invasive means that it has penetrated through the basement membrane and now has the capacity to metastasise.
