MBC - Histopathology

Question 1

What does a histopathologist do?

Answer 1

Deal with tissues - they will examine secretions of tissue noting the architecture and then using this to see what it tells us about a particular condition

Question 2

What does a cytopathologist do?

Answer 2

Deals with cells - will take a sample of cells, prepare them for examination and then deliver their expert diagnosis on the sample.

Question 3

What pieces of information does a Histopathologist deal with?

Answer 3

Biopsies
Resection Specimens
Frozen Section
Post mortems

Question 4

How long do biopsies take?

Answer 4

2-3 days to reach clinician

Question 5

What are biopsies?

Answer 5

Small sections of tissues removed from patient and then placed in formalin preservative

Question 6

What does formalin do?

Answer 6

Preserves tissue by cross linking proteins

Question 7

after placing the tissue in formalin, what is done to biopsy section?

Answer 7

Then embedded in paraffin wax so that very small sections can be cut using a microtome and then analysed on a glass microscope

Question 8

What is the main thing we try and answer with a biopsy?

Answer 8

Diagnostic questions e.g. is there a need for surgery? Is the tissue cancerous/inflamed/normal?

Question 9

What else may be used along side a biopsy?

Answer 9

Chemical stains e.g. H&E or Ziehl-Neelsen Stain to show up acid-fast bacteria

Question 10

What are resection specimens?

Answer 10

Taken from tissue that’s been removed from patient as part of the surgical procedure.

Question 11

How long do resection specimens take?

Answer 11

5-7 days to reach clinician

Question 12

What are resection specimens primarily used for?

Answer 12

To look at the progression of a disease e.g. has the cancer penetrated the underlying tissue/has it all been removed?

Question 13

What are frozen sections?

Answer 13

Tissue is taken during surgery and then frozen in cryostat and stained for a biopsy

Question 14

How long do frozen sections take?

Answer 14

30 minutes

Question 15

What 3 questions do we ask from a frozen section?

Answer 15

Is the tissue cancerous?
Has all the cancer been removed?
Are there any other pathologies occurring?

Question 16

What is the main purpose of frozen sections?

Answer 16

Relayed back too surgeon to inform the surgery.

Question 17

When may fine needle aspirates be used?

Answer 17

Used for relatively inaccessible regions such as the thyroid - the suspect mass can be assessed without the need for surgery

Question 18

What is the downside of a fine needle aspirate?

Answer 18

Cystopathologist only looking at isolated cells and not the overall tissue architecture

Question 19

How can we improve the use of fine needle aspirate?

Answer 19

Combine with histopathology to examine individual cells but also the tissue architecture.

Question 20

How might antibodies be used for diagnosis?

Answer 20

Levels of circulating antibodies can be used for diagnosing disease. Some diseases can generate double stranded DNA circulating in the blood, which generates an autoimmune response - the degree of this response is reflected by the level of antibodies circulating e.g. SLE, rheumatoid arthritis, Sjögren’s syndrome.

Question 21

What are antibody conjugations?

Answer 21

Molecules that are attached onto the Fc region of antibodies

Question 22

What molecules may be used as conjugates?

Answer 22

Enzymes
Fluorescent probes
Magnetic beads
Drugs

Question 23

When might we use enzymes as conjugates?

Answer 23

E.g. peroxidase - if we add a colourless substrate that turns into a coloured product, then the use of enzyme conjugates is useful for determining the location of an antigen

Question 24

When might we use fluorescent probes as conjugates?

Answer 24

These can allow for the rapid measurement of the levels of molecule in a sample

Question 25

When might we use magnetic beads as conjugates?

Answer 25

E.g. the purification of cell types (very quick)

Question 26

When might we use drugs as conjugates?

Answer 26

E.g. Kadcycla is an anti HER2 antibody which is attached to the cytotoxic chemical emtansine - therefore over-expression of HER2 in breast cancer is treated with emtansine.

Question 27

What can we detect with antibodies?

Answer 27

Not only proteins, but also carbohydrates and lipids too

Question 28

What is direct detection?

Answer 28

A primary conjugate antibody binds to an antigen

Question 29

What is indirect detection?

Answer 29

A secondary conjugate antibody binds to a primary conjugate antibody which binds to an antigen

Question 30

When might antibodies be useful for determining the level of a molecule in a clinical sample?

Answer 30

Enzyme Linked ImmunoSorbent Assay - serum samples adhered to plastic plate are probed with specific antibody against the molecule of interest. Colourless to coloured enzyme when antigen binding - can work out level through solution absorbance.

Question 31

What is flow cytometry?

Answer 31

Used for denoting subpopulations of cells in a sample e.g. types of lymphocyte. We conjugate different antibodies to different fluorophores which bind to cell markers - help us see the variation of population.

Question 32

How do we also gauge the identity/size/ granularity of the cell surface molecules expressed?

Answer 32

Labelled cells run as a stream through a laser beam. Side scatter is coupled with the light emitted from the laser beam reacting with fluorophores of the different antibodies, which then is used to denote extra properties