Histopathology Flashcards
What does a Histopathologist do?
- deals with TISSUES
- examines sections and notes architecture of tissue
what is done with the information histopathologists collect?
- info used to make a diagnosis
- inform efficacy of a particular treatment
- may tell you if the patient needs surgery?
What tissue samples do histopathologists work with?
- Biopsies
- Resection specimens
- Frozen sections
- Post-mortems
What are biopsies?
Small sections of tissues that are removed from the patient.
What are biopsies preserved in?
Formalin solution
How are biopsies preserved?
Formalin cross-links proteins
What are biopsies embedded in and why?
Paraffin wax to allow very thin sections (2-3μm thick) to be cut.
What are biopsies cut with?
An instrument called MICROTOME
then mounted on a glass slide for further prep.
What questions can the examination of a biopsy answer?
- Is the tissue normal?
- Is the tissue inflamed and, if it is, what is the likely cause?
- Is the tissue cancerous and, if it is, what type of cancer is it?
What can help to identify cells in a biopsy section? Give examples.
Chemical stains
- Haemotoxylin & Eosin (H&E) staining can be used to identify nuclei and cytoplasmic granules of leukocytes within tissues.
- Ziehl-Neelsen stain will stain acid-fast bacteria red.
What aids the diagnosis of Tb?
Ziehl-Neelsen stain
What are Resection specimens?
They are taken from tissue that has been removed as a part of a surgical procedure and can be processed for a biopsy.
What do resection specimens mainly look at?
The stage of the disease. e.g. Cancer - how far has it progressed? Has it penetrated the bowel wall and spread to lymph nodes or liver? Is chemo needed?
What are other uses of resection specimens?
They can be donated to biobanks and can form genomic studies of the disease.
What are frozen sections?
Tissues taken during surgical procedures and examined while the patient is being operated on
What is a cryostat?
A machine that freezes the fresh tissue taken in a surgical procedure.
What is the process of examining frozen sections?
- Tissue taken
- Tissue is frozen by cryostat
- cut and mounted on glass slides
- stained and examined.
What kinds of questions can the examination of frozen sections answer?
e.g.
Is the tissue cancerous?
Has all the cancerous tissue been removed?
Is there another pathological process going on?
What makes tissues compatible to be examined as frozen sections?
sample must be fresh and free of preservatives such as formalin but not all processes are compatible with the preparation of the sample.
How long does a Biopsy take to get results?
2-3 days
How long does a frozen section take in getting results?
30 mins
How long does a resection specimen take to get results?
5-7 days
What do cytopathologists work with?
Cells which are collected and smeared onto a microscopes slide.
they are stained and examined
What can be used to get into a lesion?
Fine needle- fine needle aspirate
Why is fine-needle aspiration powerful?
The needle can penetrate relatively inaccessible tissue and suck out cells.
What is an example of a use for fine-needle aspiration?
Can analyse a thyroid nodule and assess the mass without the need for surgery.
What is a Con of fine needle aspiration?
The cytopathologist is only looking at cells - cant comment on likely architecture of tissue.
What can manufactured antibodies be used for?
Specifically detecting molecules in the process of immunohistochemistry
What are conjugations?
These are attachments to the Fc region of the antibody.
What are the different types of antibody conjugates?
Enzymes
Fluorescent probes
Magnetic beads
Drugs
How are enzymes as conjugates useful?
They can detect receptors of cancerous tissue e.g. breast cancer - oestrogen receptors.
enzymes such as peroxidase, alkaline phosphate are used with colourless substrates and then they give a coloured product - CD31 staining
What do Fluorescent probes do?
- can allow rapid measurement of levels of molecules in a sample.
MULTIPLEXING ( using several ab with diff fluorescence) can allow measurement of several molecules in a single sample ( some = v small so it’s efficient)
What are magnetic beads used for?
- Purification of cell types ( cells can be depleted of contaminants)
Example of magnetic beads being used
anti-CD3 ab used to deplete bone marrow of T cells prior to use in bone marrow grafts
What is the biological Kadcyla?
an anti-HER2 ab linked to a cytotoxic chemical (emtansine) to treat metastatic breast cancers. (HER2 = overexpressed in 30% of breast cancers)
