Histopathology Flashcards
What are biopsies
Small sections of tissues which are removed from the patient and placed in a formalin solution which preserves tissues by cross linking proteins
Where are the biopsies placed
Embebed in the paraffin wax to allow very thin sections which are usually just about 2-3micrometers thick so they can be cut by a microtome
Then placed in a microscope
What are the questions asked when looking at a biopsy 3
Is it normal
Is it inflamed
Is it cancerous and what type
Easier to make diagnosis
What are the chemical stains used also 3 here
haemotoxylin and eosin to identify nuclei and cytoplasmic granules of the leukocytes within the tissues
Ziehl - Neelsen stain which will stain acid fast bacteria aiding the diagnosis of TB
How long is needed for a biopsy
2-3 days
What is always needed for samples to be done before analysis
Don’t over think, it is simple
Always label correctly and avoid confusion and misdiagnosis
What is a resection specimen
It is taken from tissues removed as part of a surgical procedure and processed as a biopsy
What is it used for and what questions are asked 2
Used to look for the stage of the disease
How far it has progressed and how has it spread
What other thing can be done with this tissue without regarding the patient
Can be donated to bio banks and used to inform genomic studies of the disease process with the input of other medical professional such as immunologists and microbiologists
How long for a resection specimen
5-7 days
What is a frozen section
It is taken during the surgical procedure and examined by the pathologist in real time while patient operated on
What is the procedure
The freshly cut section is frozen by a machine known as a cryostat and mounted on glass slides and stained. Then analysed as biopsies
Why is it preferred during surgery
Very fast only 30 minutes
What questions can it answer? 2
Is it cancerous
Is all cancer removed
What is a problem with this technique
Not all processes are compatible with the initial preparation of the sample
What is the process for cytopathology 4
Collect cells
Smear on microscope
Stain
Slide stain and examine
How can cells be extracted
Fine needle to be used to get into a lesion and aspirate cells which can be analysed for a smear
What can a cytopathologist comment on
Just the cells not the architecture of the tissues — only a histopathologists can do that
How many tests for antibodies
86 different diagnostic tests
What can the antibodies test for 4 disease but can be any really
DNA, systematic lupus erythematosus , Sjongens syndrome, rheumatoid arthiritisn
What can antibodies form when attaching to other things and where do these others attach
Conjugations, they attach at the Fc regions
What are the 4 things they can attach to
Enzymes, fluorescent probes, magnetic beads, drugs
What can you say about enzymes conjugation?
Peroxidase and alkaline phosphotase which can change colour of one thing can show presence.
Explain fluorescent probes
Rapid measurements of levels of molecules within sample because the colour is there
Can do multiplexing with several antibodies within the solution, several molecules in a sample
Why is multiplexing important
Some samples are really hard to obtain so more information we can get from them the better
How can we use magnetic beads
Purifying cell types by attaching to Fc region which allows cells to be purified
eg anti CD3+ can be used for depleting the bone marrow of T cells before we use them for bone marrow grafts
Drugs on antibodies
Kadcyla - an anti HER2 antibody linked to cytotoxic chemical emstansine to allow treat breast cancer.
Her expressed in 30% of cancers
Approved for advanced metastatic cancers
What are the two types of diagnostic tools and what are they
Direct - antibody to antigen
Indirect - antigen and antibody and secondary antibody
What are some uses of the antibodies? 3
Blood group serology
Immunoassay - detect hormones and circulating antibodies/ antigens
Immunodiagnosis — infectious diseases, antibody levels, IgE hypersensitivity - allergic phenotype
High levels of antibodies can be suggested of a myeloma
Describe ELISA test
Clinical samples on plastic plate
Probe with specific antibody raised against the molecule of interest.
Enzyme conjugation generates a coloured product
Reference to a standard curve the relative absorbance determine precise concentrations of molecule of the sample
It allows us to measure the amount
Describe flow cytometry
It allows measurements of specific cells particularly lymphocytes
Fluorescent antibodies specific for leucocyte antigens but have different colour
Runs as single cells through a laser beam and excite the flourophores on these and the colour of light emitted coupled with forward or side scatter tells us identity - size and granularity
Can work out which white blood cells are included and see which inflammatory reaction is occurring
Say the CD+ number for each of these Pan T cell marker t helper cells t cytotoxic cells B cells natural killer cells
3 4 8 19 56
