1. Introduction to Histopathologic and Cytologic Techniques

Histopathology

The study of the abnormal or the diseased parts of a tissur or tissues of an organ or organs with the use of microscopic techniques

Histopathologic and Cytologic Techniques

Deals with the preparation of tissues for microscopic study

Autopsy

Opening the body of a cadaver/medical exam of dead human body to determine the cause of death, diagnosis, or disease progression

Biopsy

Removing or examining the tissues from the living body as a result of surgery

Exfoliative Cytology

Microscopic examination of cells in body tissues or body fluids primarily to determine if they are cancerous

Papanicolau

Method of staining used in exfoliative cytology

External Growth

Any abnormal growth of tissue being removed from the external surface of the body

Surgical Growth

A growth of an organ within the body, removed through incision. It can be a removal of the mass or together with the mass and the organ itself.

Endoscopic Growth

A growth within the body in a natural opening. This is for hollow organs like colon, intestine, or esophagus.

Puncture

Kind of minor surgical procedure whereby a blunt instrument or needle is used to obtain samples of tissue

Aspiration

Process of removal of fluid or soft tissue from the body by inserting a pointed instrument and subsequent withdrawal of the material for examination

1. Size (in mm)

2. Color

3. Consistency

4. Other Features (cystic changes, areas of hemorrhage, gritty areas of calcification, extent of necrosis)

These are checked by the pathologist for gross examination:

Specimen Accessioning

Should be done immediately once the specimen is received in the laboratory

Fixation

Most crucial step in routine tissue processing

Fixation

Preserves the shape, structure, intracellular relationship, and chemical constituents of the tisses

Formalin

Most common fixative

Dehydration

Removal of intracellular and extracellular water from the tissue

Ethanol

Most common dehydrating agent

Decalcification

Additional step done to calcified tissues or organs to remove calcium ions and soften the tissue for easier cutting

Nitric Acid

Most common decalcification agent

Clearing

Removal of the dehydrating agent which results into a translucent tissue increasing its refractive index

Xylene

Most common clearing agent

Infiltration

A process that completely removes the clearing agent

Infiltration

Fills up all the tissue cavities that provides a firm and hard consistency and easy handling and cutting of thin tissue sections

Parrafix Wax

Most common infiltrating agent

Embedding/Casting/Blocking

Arranging the infiltrated tissue in a mold that contains the medium used to infiltrate the tissue

Sectioning

Embedded tissue is trimmed and cut into uniformly thin slices forming the tissue ribbon

Hematoxylin and Eosin

Stain used for surgical samples

Papanicolau stain

Stain used for cytological samples

Mounting

Used for permanent preservation of the slide

Frozen Section

Used if there is a need for biopsy while the patient is still in surgery

Autolysis

The destruction of the tissues (breaking down of the protein of the cell) by enzymes which are produced by the tissues and eventually liquefy it. It is the first to occur among all post-mortem changes.

Putrefaction

The decomposition of organic matter under the influence of microorganisms accompanied by the development of disagreeable odors.

Degeneration

A retrogressive pathologic process in cells in which the cytoplasm undergoes deterioration while the nucleus is preserved.

Teasing or Dissociation

Process wherein selected tissue specimen is immersed in a watch glass containing isotonic salt solution, carefully dissected or separated and examined under the microscope

Anatomical relationship is destroyed

Disadvantage of teasing/dissociation technique

Squash Preparation or Crushing

Process where small pieces of tissue not more than 1 mm in diameter are placed in a microscope slide and forcibly compressed with another slide or with coverglass

Squash Preparation or Crushing

Utilizes the incorporation of vital stain through capillary action

Microincineration

Used to locate the presence of mineral elements in the tissue which used 2 or duplicated sections of alcohol-fixed tissues

Polarizing Microscope

Often used to examine the ash residue of the incinerated section

Autoradiography

Direct injection of radioactive isotopes into organs

Frozen Section

Normally utilized when a rapid diagnosis of the tissue in question is required, and especially recommended when lipids and nervous tissue elements are to be demonstrated

Smearing

Useful in cytological examinations, particularly for cancer diagnosis

Streaking

Rapid and gentle direct or zigzag application to obtain uniform distribution

Spreading Technique

Little more tedious than streaking, but has advantage in maintaining the intracellular relationship; Especially recommended for fresh sputum, bronchial aspirates, and thick mucoid secretions

Pull-apart Technique

The material disperses evenly over the surface of 2 slides. A single uniterrupted motion of pulling apart is apploed. It is useful for serous fluids, concentrated sputum, enzymatic GIT lavage and blood smears.

Touch Preparation or Impression Smear

Special method where slide surface is in contact and pressed on the site. Cells may be examined without destroying their actual intercellular relationship and without separating them from their normal surroundings.

0.2-0.5 mm

Thickness of wet mount preparation

Canada Balsam

Recommended mounting medium

3.0-5.0 mm

Thickness of sectioning for histopathologic specimens.

<5 mm thickness with minimum handling and squeezing and must be covered with several layer of gauze before immersion

When sectiong lung/edema/air-filled lungs, what should be considered?

Diagnostic Cytology

Simply means microscopic examination of cells from different body sites for diagnostic purposes

Exfoliative Cytology

Deals with the microscopic study of cells that have been desquamated from epithelial surfaces

Fresh Tissue Examination

Observation of physiological processes such as mitosis, phagocytosis and pinocytosis

• Enterovirus

• Adenovirus

• Reovirus

Viruses that are resistant to ethyl ether as fixative