Neoplasia Flashcards
Revision
What is the definition of cancer?
To a pathologist: Uncontrolled cell proliferation and growth that can invade other tissues
What is a tumour?
Swelling.
Can be benign or malignant.
May even by inflammatory.
Could be a foreign body.
If a tumour is big, is it more likely to be benign or malignant?
Malignant
If a tumour is very big but the skin is intact has it grown quickly or slowly?
It is more likely to have grown slowly because the skin is intact. If it had grown quickly the skin wouldn’t have stretched.
What is a neoplasm?
The literal translation of neoplasia is new growth.
Not in response to a stimulus (see hyperplasia).
Can be benign, premalignant or malignant. Often used as a clinician code for cancer - remember not true.
The plural of neoplasm is neoplasia.
Where do you get a neoplasm?
Anywhere.
Only part of the body not reported to have undergone neoplastic change is the lens of the eye.
Any cell from any organ.
Normal cells.
Epithelium -mucinous, oxyntic cells, smooth muscle, nerves, inflammatory cells, stromal cells, pacemaker cells (interstitial cells of cajal), neuroendocrine cells, blood vessels (endothelium).
Tumours o them all can occur but obviously some are more common than others.
How do you define benign compared to malignant?
Difficult to come up with an accurate definition.
Malignant tumours have metastatic potential (metastatic potential reflects the cumulative effect of a wide variety of genetic and epigenetic changes involving tumour cell adhesion, motility, and protease production).
Metastases spread to other sites.
Epithelium has a basement membrane. Malignancy goes beyond basement membrane.
Why is it not as simple as cells being either benign or malignant?
Clearly things don’t just all of a sudden become malignant.
There are precursor stages.
This is often the basis of screening programmes.
Precursor lesions:
- Dysplasia
- Metaplasia
- Even hyperplasia
What is the definition of metaplasia?
Reversible change from one mature cell type to another mature cell type.
How does metaplasia come about and is it reversible?
Metaplasia is not reversal in the appearance of adult cells.
Represents a change in signals delivered to stem cells causing them to differentiate down a different line.
May be in response to cytokines (chemical messengers), growth factors and other chemicals in the cells microenvironment.
Commonly occurs in response to a noxious stimulus.
Squamous epithelium covers your skin and is very resistant to a range of noxious stimuli.
Squamous metaplasia is therefore commonly encountered in response to injury - lung an salivary ducts.
You get a lot of squamous epithelium where?
Lung Bronchial epithelium - cilia allow clearance of mucous etc. No good with thermal/chemical injury. Turns to squamous epithelium. Bladder Usually transitional epithelium. Catheter - creates inflammation. Epithelium changes to squamous.
Does Hyperplasia require a signal or can it be autonomous?
Hyperplasia - the other ‘asia’ associated with cancer.
Can be autonomous and no longer require stimulus.
Basic structure of steroid hormones is shared by cholesterol (obese individuals are at massively increased risk).
Is Dysplasia always in response to a stimulus or is it ever autonomous and how is it graded?
Literally it is disordered growth
In abnormal cells, growth is not in response to a stimulus (remember hyperplasia).
No invasion.
Invasion - growth beyond the basement membrane.
Dysplasia - often graded. Low grade most normal. High grade most abnormal and closest to becoming cancer.
Why do we grade dysplasia?
We often grade dysplasia because we know it reflects the likelihood of malignancy.
High grade, high risk of becoming a malignancy.
Low grade, low risk of becoming a malignancy.
What is the aim Cervical Screening?
Aim is to catch the dysplasia before it becomes malignant.
Forms the basis of smears and previous screening methods.
Detection of disordered growth in the cervix. Aim is to catch dysplasia before it becomes cancer.
