Diagnostic Techniques In Histopathology 🙂 Flashcards
(31 cards)
Different areas in pathology
Surgical, cyto, histo, autopsy pathology
Another name for histopathology
Surgical, cellular, anatomic pathology
Surgical pathology
A method of making a diagnosis on a tissue on gross(macro) or microscopic examination eg tumor from the breast
Protocols of surgical pathology
It includes the request form, tissue accession(tissue processing), gross room, histopathology lab, surgical pathology report, quality control, histopathology and the law
Specimens are received in two forms namely
- 10% formalin(buffered or fresh) it means the patient is still in the theatre and a frozen portion of the specimen is needed intraoperative(i.e frozen under liquid nitrogen -5°C) also called cryostat operative
- Formal saline
Steps in tissue processing
- fixation
- dehydration
- clearing
- impregnation
- embedding
What is fixation
The tissue is fixed in a 10% normal saline while the brain is fixed at 20% normal saline
What is dehydration
It’s putting the tissue in ascending grades of alcohol i.e 70 to 90 to 95 to absolute(100) to remove the water from the tissue
What is clearing
It’s clearing of the alcohol with either xylene or toulene but xylene is commonly used
What is impregnation
It’s impregnating the tissue with wax
What is embedding
It’s embedding with wax, it’s in this form that we section the tissue into cassettes form
The diagnostic techniques in histopathology are
- light microscope
- electron microscope
- immunohistochemistry
- flocytometry
- cytogenetics analysis
- molecular pathology
Light microscope
It is a basic tool used to magnify minute specimens using both the objective and eye piece lenses
There are two types of microscope namely
Simple and compound microscope
(Know the differences)
There are two types of modifications done on a light microscope which are
Dark field and polarizing microscope
What is dark field or dark field illumination
It’s used for the examination of unstained living micro organisms such as treponema palladium (spirochetes). The light from this microscope don’t pass through the micro organisms but the periphery
What is polarizing microscope
It’s used to demonstrate high birefringence, amaloids, foreign bodies, hair etc. The light passes through the micro organisms
In the polarizing microscope, how many discs does it have
It has 2 namely: polarizer(below the obj), analyzer(within the tube)
Some types of special stains are
Congo red stain used to detect amaloid i.e a green birefringence amaloids (deals with the rays)
High periodic acid schiff(PAS) used for highlighting carbohydrates, fungi and basement membrane. It’s used to differentiate glycogen from fungi i.e PAS diastasis
Van gieson stain used for extracellular collagen (for connective tissue)
Gieson-tricone used for extracellular collagen (for connective tissue)
Petha phosophotonsic stain used for muscle and myofilaments (connective tissue)
Acid hematoxylin for muscle and myofilaments (connective tissue)
Vel elastic stain for elastic fiber
Gordon and sweet silver staining for reticular fibers
Special stains for identification of lipids
Oil redo and Sudan block
SS for microorganisms are
- gram stains
- Ziehl neelsen stain for Tuberculosis bacilli
- Fite-wade stain for leprosy bacilli (modified Ziehl neelsen stain)
- grocott methanamine silver for fungi
- germsa stain for parasite
- shikata-orcein
- perls-prussian blue
- fontana-masson stain for fungi
- von kossa stain for calcium
What does enzyme histochemistry require
It requires fresh specimen and place them in cryostat with liquid nitrogen at -5°C
Electron microscopy has a diagnostic use in pathology in the following areas
- urinal pathology
- assist in the detection of ultra structure of tumor
- assist in subcellular study in microphages
- for research purposes
Types of electron microscope are
- transmission electron microscope
- scanning electron microscope
