Histologic Technique Flashcards
It deals with the preparation of tissues for microscopic examination
Histological Technique
What happened if a tissue is removed from the body or cut off from its blood supply
Decomposition occurs
Decomposition results from:
Deprivation of oxygen
Accumulation of carbon dioxide
Autolysis
Decomposition occurs in what following organs?
Kidney
Liver
Pancreas
This is where the tissue specimen from the operating theaters and clinics are received
Specimen Reception Laboratory
Accurate diagnosis is dependent upon correct what?
Identification
Handling
Processing
It may include the year and month the specimen was received.
Accession number
This are frequently used by clinical laboratories
Bar codes
The specimen container label and the accompanying request form should include:
Patient’s name
Age or birth date
Medical record number
Where should the label be firmly attached?
Attached to the body of the container
What does a request form should have
Provisional diagnosis and brief clinical details.
People who can gross specimen
Pathologist
Resident
Physician assistant
The type of biopsy and the number of fragments received should be documented
Grossing
This should not be cut, bisected, or inked while fresh and infixed.
Small specimens
This is where the small specimens should be processed
Lens paper or in a tea bag
Usually taken with a larger lesion or of a generalized inflammatory or other diseases process.
Core biopsies
Should be bisected eccentrically and embedded (4mm)
Larger core biopsies
Should be embedded totally without cutting it (2mm)
Small core biopsies
Depending upon the size of the biopsy, other epithelial surfaces should cut
Shave biopsies of skin
Method of choice for surgical removal of whole organ
Excisional biopsy
Original site of a lesion may need to be re-excised if the margins are invaded by tumor
Re-excision specimen
Operative specimen
Non skin specimen
All specimens must be examined carefully because:
It may harbor unsuspected malignant
Important determinants of neoplastic specimen
Tumor
Special care due to diagnostic difficulties of pediatric lesion/ disease
Pediatric specimen
Processing of tissues
- Identification- Gross Examination & Accessioning
- Fixation
- Decalcification- removal of calcium
- Dehydration – removal of water using alcohol.
- Clearing- remove excess alcohol
- Infiltration / Impregnation
- Embedding- solidify
- Trimming- cut excess
- Section Cutting –microtome to have tissue sample / tissue ribbon
- Staining – H&E staining (commonly used)
- Mounting- process slip
12.Labeling – label accession number
Microscopic study of the normal tissue
Histology
Microscopic study of tissue affected by the disease
Histopathology
Simplest, least invasive, not always adequate to obtain diagnosis
Fine needle aspirations
Remove not only cells but also small amount of tissue
Core needle biopsy
Takes out some abnormality, remove only a portion
Incisional biopsy
Remove entire area
Excisional biopsy
Primary technique, diagnostic
Punch biopsy
Small fragments are shaved
Shave biopsy
Scooped or spooned
Curettings
Methods of tissue examination
Fresh tissue examination
Fixed Tissue examination
Methods of fresh tissue examination
Teasing or dissociation
Squash preparation
Smear preparation
Frozen section
Tissue specimen is immersed in a watch glass containing isotonic normal saline solution
Teasing and dissociation
These are the microscopes that can be used in teasing or dissociation
Bright field microscopy
Phase contrast microscopy
Tissues are placed in a microscopic slide forcibly compressed with another slide or coverslip
-< 1mm thick of tissues
Squash preparation
Smears should be from fresh material, cellular materials are spread lightly
Smear preparation
Methods of smear preparation
Streaking
Spreading
Pull-apart
Touch
It is a smear preparation method and it is used for preparing. Ex: mucoid secretion, vaginal secretion, gastric content
Streaking
It is a smear preparation method and it is used for thick mucoid secretions. Ex: smears of fresh sputum, bronchial aspirates
Spreading
It is a smear preparation method that is used for serous fluids, concentrated sputum, vaginal pool
Pull-apart
It is a smear preparation method and it is used for preparation of direct impression. Ex: lymph nodes, autopsy secretion
Touch or impression smear
Utilized when rapid diagnosis of tissue is required
Frozen section
Frozen section is recommended for:
Nervous tissue/lipids
Thicknesses for frozen section
10-15um
Temperature for frozen section
-10 - -20C
Frozen section limitation
Freezing artifacts
Inferior quality
Lack of consultation
Optimal turn around time
< 15mins
Cryostat temp for rfs
-17C
2 methods of preparing frozen section
Cold knife procedure
Cryostat procedure
Microtome for cold knife procedure
Cryostat
Microtome for cryostat procedure
Cold microtome
Optimum condition for sectioning (cold knife procedure)
Knife- -40 to -60C
Tissues- 5 to -10C
Environment- 0 to 10C
Optimum working temperature for cryostat procedure
-18 to -20C
A refrigerated cabinet in which a modified microtome is housed
Cryostat
Best for frozen section, has a synthetic water soluble glycols and resins
Mounting media
Freezing agents
Liquid nitrogen- common
Isopentate cooled by liquid nitrogen
Carbon dioxide gas
Aerosol spray