Histopathology Flashcards
What does a histopathologist do?
Deals with tissues
What does a cytopathologist do?
Deals with cells
What is a biopsy?
Small sections of tissue removed from patient.
Explain how a biopsy is prepared?
Typically placed in formalin solution which preserves tissue by cross-linking proteins
Sample is embedded in paraffin wax to allow v thin sections (2-3 micrometers thick) to be cut out by a MICROTOME
mounted on a glass slide and further prepped before analysis
List the stains, and what they stain, used in biopsy specimen
Haematoxylin & eosin (H&E):
- used to identify nuclei and cytoplasmic granules of leukocytes within tissues
Ziehl-Neesen:
- acid-fast bacteria (red), aiding diagnosis of TB infection
What is a resection specimen?
Taken from a tissue removed as part of a surgical procedure and can be processed as for a biopsy
What is resection used for primarily?
Looking at the stage of disease
What is the tissue from resections also used for?
Donated to biobanks and used to inform genomic studies of disease process
What is a frozen section?
it is taken during a surgical procedure and examined by the pathologists in real time while patient is being operated on
How is the frozen specimen produced?
Tissue is frozen in cryostat, cut and then mounted on a glass slide and stained as for biopsies
What does tissue for frozen sections have to be which differs from the others?
Fresh and free of preservatives - like formalin
Timings for each method
frozen section: 30 mins
biopsies: 2-3 days
resection specimen: 5-7 days
What is cytopathology?
Working with cells which are collected and then smeared onto a microscope
What are fine needle aspirates used for?
To get into a lesion and suck out (aspirate) the cells which can be analysed as for a smear
Why is a fine needle aspirate useful?
It can penetrate relatively inaccessible tissues (e.g. thyroid nodule) and assess the suspect mass without the need for surgery
What is the downside to a fine needle aspirate?
Cytopathologist is unable to comment on likely architecture of tissue
What is Kaposi’s sarcoma?
Rare cancer indicative of immunodeficiency (e.g. in AIDS)
Spindly looking cells penetrate collagen fibres
What does an antibody have to recognize on an endothelial cell for it to be an endotehlial cell diagnosis?
CD31 marker
What can be measured through antibody levels?
Degree of autoimmune response
Name three autoimmune diseases
Systemic Lupus Erythematosus (SLE), Sjörgen’s syndrome, rheumatoid arthritis
What are the 4 antibody conjugates?
Enzymes
Fluorescent probes
Magnetic beads
Drugs
Give examples of enzyme conjugates.
Peroxidase, alkaline phosphatase (catalyse a reaction on specific receptors we want -> colourless dye to colour e.g. in CD31)
Give examples of fluorescent probes.
These can allow the rapid measurement of the levels of molecules within a sample.
Why are fluorescent probes so useful?
Multiplexing - several different antibodies with different fluoroprobes identify different cells which is important as some samples are incredibly precious
