MBC - Histopathology Flashcards
What does a histopathologist do?
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
What does a cytopathologist do?
Deals with cells - will take a sample of cells, prepare them for examination and then deliver their expert diagnosis on the sample.
What pieces of information does a Histopathologist deal with?
Biopsies
Resection Specimens
Frozen Section
Post mortems
How long do biopsies take?
2-3 days to reach clinician
What are biopsies?
Small sections of tissues removed from patient and then placed in formalin preservative
What does formalin do?
Preserves tissue by cross linking proteins
after placing the tissue in formalin, what is done to biopsy section?
Then embedded in paraffin wax so that very small sections can be cut using a microtome and then analysed on a glass microscope
What is the main thing we try and answer with a biopsy?
Diagnostic questions e.g. is there a need for surgery? Is the tissue cancerous/inflamed/normal?
What else may be used along side a biopsy?
Chemical stains e.g. H&E or Ziehl-Neelsen Stain to show up acid-fast bacteria
What are resection specimens?
Taken from tissue that’s been removed from patient as part of the surgical procedure.
How long do resection specimens take?
5-7 days to reach clinician
What are resection specimens primarily used for?
To look at the progression of a disease e.g. has the cancer penetrated the underlying tissue/has it all been removed?
What are frozen sections?
Tissue is taken during surgery and then frozen in cryostat and stained for a biopsy
How long do frozen sections take?
30 minutes
What 3 questions do we ask from a frozen section?
Is the tissue cancerous?
Has all the cancer been removed?
Are there any other pathologies occurring?
What is the main purpose of frozen sections?
Relayed back too surgeon to inform the surgery.
When may fine needle aspirates be used?
Used for relatively inaccessible regions such as the thyroid - the suspect mass can be assessed without the need for surgery
What is the downside of a fine needle aspirate?
Cystopathologist only looking at isolated cells and not the overall tissue architecture
How can we improve the use of fine needle aspirate?
Combine with histopathology to examine individual cells but also the tissue architecture.
How might antibodies be used for diagnosis?
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.
What are antibody conjugations?
Molecules that are attached onto the Fc region of antibodies
What molecules may be used as conjugates?
Enzymes
Fluorescent probes
Magnetic beads
Drugs
When might we use enzymes as conjugates?
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
When might we use fluorescent probes as conjugates?
These can allow for the rapid measurement of the levels of molecule in a sample
When might we use magnetic beads as conjugates?
E.g. the purification of cell types (very quick)
When might we use drugs as conjugates?
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.
What can we detect with antibodies?
Not only proteins, but also carbohydrates and lipids too
What is direct detection?
A primary conjugate antibody binds to an antigen
What is indirect detection?
A secondary conjugate antibody binds to a primary conjugate antibody which binds to an antigen
When might antibodies be useful for determining the level of a molecule in a clinical sample?
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.
What is flow cytometry?
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.
How do we also gauge the identity/size/ granularity of the cell surface molecules expressed?
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
