Histopathology

Question 1

What does a Histopathologist do?

Answer 1

• deals with TISSUES

- examines sections and notes architecture of tissue

Question 2

what is done with the information histopathologists collect?

Answer 2

• info used to make a diagnosis
• inform efficacy of a particular treatment
• may tell you if the patient needs surgery?

Question 3

What tissue samples do histopathologists work with?

Answer 3

• Biopsies
• Resection specimens
• Frozen sections
• Post-mortems

Question 4

What are biopsies?

Answer 4

Small sections of tissues that are removed from the patient.

Question 5

What are biopsies preserved in?

Answer 5

Formalin solution

Question 6

How are biopsies preserved?

Answer 6

Formalin cross-links proteins

Question 7

What are biopsies embedded in and why?

Answer 7

Paraffin wax to allow very thin sections (2-3μm thick) to be cut.

Question 8

What are biopsies cut with?

Answer 8

An instrument called MICROTOME

then mounted on a glass slide for further prep.

Question 9

What questions can the examination of a biopsy answer?

Answer 9

• 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?

Question 10

What can help to identify cells in a biopsy section? Give examples.

Answer 10

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.

Question 11

What aids the diagnosis of Tb?

Answer 11

Ziehl-Neelsen stain

Question 12

What are Resection specimens?

Answer 12

They are taken from tissue that has been removed as a part of a surgical procedure and can be processed for a biopsy.

Question 13

What do resection specimens mainly look at?

Answer 13

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?

Question 14

What are other uses of resection specimens?

Answer 14

They can be donated to biobanks and can form genomic studies of the disease.

Question 15

What are frozen sections?

Answer 15

Tissues taken during surgical procedures and examined while the patient is being operated on

Question 16

What is a cryostat?

Answer 16

A machine that freezes the fresh tissue taken in a surgical procedure.

Question 17

What is the process of examining frozen sections?

Answer 17

1. Tissue taken
2. Tissue is frozen by cryostat
3. cut and mounted on glass slides
4. stained and examined.

Question 18

What kinds of questions can the examination of frozen sections answer?

Answer 18

e.g.
Is the tissue cancerous?
Has all the cancerous tissue been removed?
Is there another pathological process going on?

Question 19

What makes tissues compatible to be examined as frozen sections?

Answer 19

sample must be fresh and free of preservatives such as formalin but not all processes are compatible with the preparation of the sample.

Question 20

How long does a Biopsy take to get results?

Answer 20

2-3 days

Question 21

How long does a frozen section take in getting results?

Answer 21

30 mins

Question 22

How long does a resection specimen take to get results?

Answer 22

5-7 days

Question 23

What do cytopathologists work with?

Answer 23

Cells which are collected and smeared onto a microscopes slide.
they are stained and examined

Question 24

What can be used to get into a lesion?

Answer 24

Fine needle- fine needle aspirate

Question 25

Why is fine-needle aspiration powerful?

Answer 25

The needle can penetrate relatively inaccessible tissue and suck out cells.

Question 26

What is an example of a use for fine-needle aspiration?

Answer 26

Can analyse a thyroid nodule and assess the mass without the need for surgery.

Question 27

What is a Con of fine needle aspiration?

Answer 27

The cytopathologist is only looking at cells - cant comment on likely architecture of tissue.

Question 28

What can manufactured antibodies be used for?

Answer 28

Specifically detecting molecules in the process of immunohistochemistry

Question 29

What are conjugations?

Answer 29

These are attachments to the Fc region of the antibody.

Question 30

What are the different types of antibody conjugates?

Answer 30

Enzymes
Fluorescent probes
Magnetic beads
Drugs

Question 31

How are enzymes as conjugates useful?

Answer 31

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

Question 32

What do Fluorescent probes do?

Answer 32

• 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)

Question 33

What are magnetic beads used for?

Answer 33

• Purification of cell types ( cells can be depleted of contaminants)

Question 34

Example of magnetic beads being used

Answer 34

anti-CD3 ab used to deplete bone marrow of T cells prior to use in bone marrow grafts

Question 35

What is the biological Kadcyla?

Answer 35

an anti-HER2 ab linked to a cytotoxic chemical (emtansine) to treat metastatic breast cancers. (HER2 = overexpressed in 30% of breast cancers)