Cellular pathology of cancer Flashcards
Define metaplasia.
A reversible change in which one adult cell type is replaced by another adult cell type
- The adult cell type which is being replaced is usually epithelial
- Adaptive
-
In the sense that it usually occurs as a result of a stimulus causing a change in the environment
- Stimulus can be physiological or pathological
- So the cell type changes to one which is better suited to the new environment
-
In the sense that it usually occurs as a result of a stimulus causing a change in the environment
Give an example of metaplasia.
Barrett’s Oesophagus:
- Stimulus - chronic acid exposure from acid reflux
- Caused oesophageal epithelial lining of change:
- Squamous → columnar
- Squamous - white on endoscopy
- Columnar - pink on endoscopy
- Squamous → columnar
Define dysplasia.
An abnormal pattern of growth in which some of the cellular and architectural features of malignancy are present
- Pre-invasive stage with intact basement membrane
- Essentially the tumour has not invaded into a neighbouring tissue
- The tumour is still within the tissue type it originated from
State some features of dysplasia.
- Loss of architectural orientation
- Cells not maturing in their normal kind of way
- e.g. Maturation of stratified squamous epithelium: basal → kerantinised at the top
- Loss in uniformity of individual cells
- Nuclei:
- Hyperchromatic = excess chromatin (high DNA concentration) which makes nuclei stain darker
- Enlarged
- Mitotic figures = cells undergoing mitosis
- Abundant
- Abnormal
- In places where not usually found
Where is dysplasia common and due to what?
- Cervix - HPV infection
- Bronchus - smoking
-
Colon - ulcerative colitis
- Ulcerative colitis = condition causing inflammation and ulceration of epithelial lining of colon and rectum
- Ulcer = discontinuity or break in a bodily membrane (e.g. skin, mucous membrane)
- Larynx - smoking
-
Stomach - pernicious anaemia
-
Pernicious anaemia = automimmune disease where body destroys intrinsic factor
- Intrinsic factor produced by parietal cells in the stomach so these cells are affected
- Intrinsic factor is required to absorb vitamin B12
-
Vitamin B12 deficiency → anaemia
- Vitamin B12 needed for normal RBC formation
-
Pernicious anaemia = automimmune disease where body destroys intrinsic factor
- Oesophagus - acid reflux
What are the grades of dysplasia?
Low grade
- Low risk of progression to invasive cancer
- More likely to be reversible
High grade
- High risk of progression to invasive cancer
- Less likely to be reversible
NOTE:
- Dysplasia and metaplasia are reversible because they are the result of a stimulus
- So the cells may revert to their original form once the stimulus has been removed
Define neoplasia.
An abnormal, autonomous proliferation of cells unresponsive to normal growth control mechanisms
NOTE: Neoplasia is the technical term, but also referred to as malignancy ot tumour
Give some characteristics of benign tumours.
-
Do not invade do not metastasise
- Does not invade - does not infliltrate BM
- Does not metastasise - spread from its site of origin
-
Encapsulated
- Tumour frequently surrounded by fibrous capsule
- This is due to interaction between tumour cells and stromal (connective tissue) cells
-
Usually well differentiated
- The tumour cells look like the tissue (cells) from which they originated
- Slowly growing
- Normal mitosis
REMEMBER:
- The first point (no invasion or metastasis) is the most important
- This is the key distinguishing feature between benign and malignant tumours
- The other points are descriptions of ways in which we recognise benign tumours - but these are not diagnostic
A benign tumour is not usually fatal unless what?
COME BACK AND EXPLAIN WHY EACH ONE WOULD BE FATAL
A benign tumour is not usually fatal uness it:
- Is in a dangerous place
- e.g. meninges, pituitary
- Secretes something dangerous
- e.g. insulinoma (pancreatic beta cell tumour)
- Gets infected
- e.g. bladder
- Bleeds
- e.g. stomach
- Ruptures
- e.g. liver adenoma
- Torts (twisted)
- e.g. ovarian cyst
Give some characteristics of malignant tumours
- Invade surrounding tissues
- Spread to distant sites
- No capsule
- Well to poorly differentiated
- Rapidly growing
- Abnormal mitosis
REMEMBER:
- This is basically the opposite of benign tumours
- The key defining factor is that it invades surrounding tissues which also allows it to spread to distant sites (metastasise)
- The other points are ways in which malignant tumours can be recognised - not diagnostic
Define metastasis.
A discontinuous growing colony of tumour cells, at some distance from the primary cancer
- Essentially cancer cells break away from original tumour then spreads to a different part of the body
- Spread through blood or lymphatics
What does metastasis depend on?
- Depends on the lymphatic and vascular drainage of the primary site
- You need to know the drainage pathway from the prmary site as this will give you an idea as to where the tumour cells could metastasise to
- Lymph node involvement has a worse prognosis than if it hasn’t spread to lymph nodes
- e.g. Colon cancer:
- Dukes A (not invaded or metastasised) - 90%,
- Dukes C (metastasised to lymph nodes) - 30%
- Percentages represent prognosis
- e.g. Colon cancer:
Name two types of benign epithelial tumours.
Papilloma
- This is a benign epithelial tumour of surface epithelium
- i.e. Eptihelium which lines body structures
- Examples of where they can present:
- Skin
- Bladder
Adenoma
- This is a benign epithelial tumour of glandular epithelium
- i.e. Epithelium which has a secretory function
- Examples of where they can present:
- Stomach
- Thyroid
- Colon
- Kidney
- Pituitary
- Pancreas
Define carcinoma.
A malignant tumour derived from epithelium
- So essentially there’s a malignant equivalent of papillomas and adenomas
NOTE: In the image you can tell that it’s a carcinoma because you can see the tumour cell invading the basement membrane
Give some examples of carcinomas.
Squamous cell carcinoma
Adenocarcinoma
Transitional cell carcinoma
Basal cell carcinoma
