Histology is the microscopic study of the normal tissues of the body
Histopathology is the microscopic study of tissues affected by disease.
Label should be firmly attached to the body of the container—not to the lid of the container
Bar codes are frequently used by clinical laboratories.
Any discrepancies in specimen identification or labeling should be resolved prior to processing.
Biopsy is the ante-mortem examination of tissues or the examination of tissue sample from the living.
Fresh tissue does not undergo tissue processing; direct observation under the microscope.
Fixed tissue undergoes whole tissue processing before viewing under the microscope
Fine needle aspiration is the simplest, least invasive test that uses smallest needle to remove cells from the area of abnormality.
Not always adequate to obtain a diagnosis.
Will depend mainly on the area to be biopsied.
Fine needle aspiration
Core needle biopsy removes not only cells but also small amount of surrounding tissue.
Provides additional info to assist lesion examination
Core needle biopsy
Incisional biopsy takes out even more surrounding tissue; slices into the lesion and remove only a portion.
Takes out some of the abnormality, but not all.
If lesion is found to be cancerous, then further surgery may be needed to remove the entire lesion
Excisional biopsy generally removes the entire area in question.
Punch biopsy is considered the primary technique for obtaining diagnostic full-thickness skin specimens.
Requires basic general surgical and suture-typing skills.
Involves the use of a circular blade rotated down through epidermis, dermis, and subcutaneous fat, yielding 3-4 mm cylindrical core tissue sample.
Punch biopsy
Shave biopsy is where small fragments of tissue are “shaved” from a surface, usually the skin.
Shave biopsy
Curettings or Curettage is where tissue is scooped or spooned to remove tissue or growths from body cavity such as endometrium or cervical canal.
Gross examination consists of describing the specimen and placing all or parts of it into a plastic cassette, in preparation for tissue processing.
One of the basis of pathologists' diagnosis.
Involves selection of elements that appear to be of clinical significance for histologic examination.
Gross examination is also known as the macro examination or gross pathology that refers to the visual inspection and examination of tissues or specimen without a need of a microscope.
The purpose of gross examination is to identify any macroscopic abnormalities such as tumor, inflammation, hemorrhage, necrosis, or other structural changes.
Findings in gross examination provides important information that guides further diagnostic test, and helps determine cause of disease or death, for comprehensive diagnosis.
Two major gross examination processes:
Fresh Tissue Examination
Preserved Tissue Examination
Fresh tissues are usually examined when there is an immediate need for evaluation.
They have the advantage of being examined in the living state, thereby allowing protoplasmic activities such as motion, mitosis, and phagocytosis to be observed.
Teasing or Dissociation is a fresh tissue exam method where:
Tissue is immersed in isotonic salt solution, carefully dissected with a needle, and separated by direct or zigzag spread using an applicator stick.
selected pieces of the tissue are transferred carefully to a microscope slide
either stained with a supravital dye or examined unstained by phase-contrast microscopy.
Teasing or Dissociation
Isotonic salt solution used: Normal saline solution or Ringer’s solution
Mounted as a wet preparation in microscope, care being taken to avoid forming bubbles
Squash Preparation or Crushing is a fresh tissue exam method where tissues less than or equal to 1mm in diameter are pressed between two slides or between a slide and a cover glass.
Vital stain is applied between the slides.
Viewed using a Phase-contrast or Bright Field microscope.
Smear preparation is a process of examining sections or sediments where cellular materials are spread lightly over a slide by means of a wire loop, applicator stick or another slide.
Includes streaking, spreading, and pull-apart.
This technique is especially useful in cytological examinations especially for cancer diagnosis.
Streaking is a smear preparation done with an applicator stick or a platinum loop, the material is rapidly and gently applied in a direct or zigzag line throughout the slide, attempting to obtain a relatively uniform distribution of secretion.
Too thin or too thick smears should be avoided.
Spreading is a smear preparation where selected portion of the material is transferred into a clean slide and gently spread into moderately thick film by teasing mucous strands w/ applicator stick.
A little more tedious than streaking, but has the advantage of maintaining cellular interrelationships of material to be examined.
Specially recommended for smear preparation of fresh sputum, bronchial aspirates, and thick mucoid secretions
Pull-apart is a smear preparation done by placing a drop of secretion or sediment upon one slide and facing to another clean slide.
Material dispenses evenly over the surface of the two slides
Two slides are then pulled apart with a single uninterrupted motion, and specimen placed under the microscope for immediate examination or applied with vital stains
Touch Preparation or Impression Smear is a special method of smear preparation whereby the surface of a freshly cut piece of tissue is brought into contact and pressed on the surface of a clan glass slide allowing the cells to be transferred directly to the slide for examination by phase-contrast microscopy or staining for light microscopic study.
It is also done in frozen section biopsy.
Tissue processing describes the various steps required to take the tissue from fixation to the state it is completely infiltrated with suitable histological wax and ready for section cutting
Common agents/equipment used in each tissue process:
Fixation – formalin
Dehydration – alcohol
Clearing – xylene/toluene
Impregnation & Embedding – paraffin
Section-cutting & Trimming – rotary microtome
Staining – Hematoxylin-Eosin stain
Fixation is the first and most critical step in histotechnology; it is a process that preserves tissues from decay, thereby preventing autolysis or putrefaction.
In fixation,
The quality of the section on the slide is only as good as the quality of the fixed tissue specimen.
A poorly processed tissue will make it difficult for the pathologist to render a proper diagnosis
The primary goal of fixation is to preserve the morphologic and chemical integrity of the cell.
With fixation, shape structure, intercellular relationship, and chemical constituent of tissues are preserved.
It is important to prevent degeneration, decomposition, putrefaction, and distortion of tissues after removal in the body.
Formalin preserves the structure of cells & extracellular components by reacting with amino groups of proteins, cross-linking them
Fixation preserves the tissues by stopping all cellular activities to view it under the microscope, as if in their original state.
They must be placed in a fixative as soon as it leaves the body, because degeneration, decay, autolysis, and putrefaction will occur once the tissue leaves the body