Theory: Chapter One
Cytology, as a tool for the purpose of the diagnosis of cervical cancer, was first introduced by Georges N. Papanicolaou in 1928. Papanicolaou devised a staining method which is still in use today, in cytology laboratories.
The Pap smear, named after its inventor, is used as a screening test to detect early stages of cervical cancer. The 50-year-old Pap smear is a simple, inexpensive technique in which cells from the cervix are scraped off during pelvic examination and are then spread onto a glass slide. Any abnormalities are detected under the microscope.
The method permits the discovery of precancerous cells at an early stage thus facilitating treatment and cure. As a result of mass screening, cancer of the cervix has luckily become very rare, at least in industrialized countries.
The majority of smears are normal and any changes take a long time to develop. If there are any abnormal cells found in the smear then the patient must come back to the hospital, for another examination which is called colposcopy, when the cervix is examined with a special microscope
When a cervical abnormality is detect at an early stage, relatively simple treatment methods can be used successfully. The chances for a complete cure of early abnormalities are almost 100%.
The most important factor in preventing the development of cervical cancer is ensuring that every woman has a Pap smear regularly.
The smear specimen must be of high quality in order to be reliable. Unfortunately, this does not always happen in current practice. This program is meant to help you to understand how cervical cancer develops, and how to prepare reliable Pap smears for diagnosis.
"Pap Smear" (description from Dorland's Medical Dictionary)
ˇ§Pap test, Papanicolaou t., an exfoliative cytological staining procedure for the detection and diagnosis of various conditions, particularly malignant and premalignant conditions of the female genital tract (cancer of the vagina, cervix, and endometrium), in which cells which have been desquamated from the genital epithelium are obtained by smears, fixed and stained, and examined under the microscope for evidence of pathologic changes. Each examination should have an individual histological description. The test is also used in detecting human papillomavirus infection, in evaluating endocrine function, and in the diagnosis of malignancies of other organs, as of the respiratory tract and lungs, gastrointestinal tract, urinary tract, and breast. Called also Pap or Papanicolaou smear and smear t. See also Papanicolaouˇ¦s stain, under stain.ˇ¨
Conventional Smear ThinPrep Smear AutoCyte Smear
The cervical/vaginal Pap smear is an adequately collected cellular sample derived from exfoliated or mechanically dislodged cells of the vagina, cervix, and in some cases, endometrium, which have been smeared on a glass slide, adequately preserved and stained, and evaluated cytomorphologically for one or more of the following purposes:
The specific collection procedure utilized will depend on the type of information required or the specific indication for performing the Pap smear. The goal of the actual collection procedure is to produce an adequate, evaluable smear of cellular material from the vagina and/or cervix which can be submitted to the laboratory, along with appropriate clinical information, to be stained and evaluated in accordance with the indication for the test. In order to accomplish this goal, the smear has to have the following characteristics:
The collection procedure actually begins with appropriate instruction of the patient regarding the test. A Pap test should be obtained:
The collection procedure continues with the taking of an accurate sexual and health history. Information which should be required on the requisition form sent to the laboratory includes:
The female genital tract is lined by epithelium:
The upper vagina has stratified squamous epithelium,
the ectocervix stratified squamous epithelium,
the endocervix simple columnar (glandular) epithelium,
and the endometrium simple columnar (glandular) epithelium.
All of these epithelia are subject to the cyclical hormonal influences of estrogen and progesterone during the menstrual cycle, which induces:
o proliferation (increase in number of cells)
o And differentiation or maturation (the development of functional and morphologic features of mature cells of the parent tissue type) of these epithelia.
o Differentiation and maturation of cells are reflected by characteristic morphologic features which staining techniques allow us to identify.
Morphologic effects on cells of retrogressive process resulting in decreased activity ˇV Retroplasia
Retrogressive or degenerative process occurs with events such as aging, injury, death and necrosis. The causes include external agents (e.g. trauma, heat, irradiation) and living organisms (e.g. bacteria, virus).
1. Loss of cellˇ¦s control over its water content
A cell unable to control its water content:
- Hydropic degeneration
- Rupture and lyses
2. Cytoplamic staining
With degeneration, cytoplasmic proteins lose their basophilia and become orange or red resulting in increased acidophilia.
3. Nuclear membrane wrinkling
Loss of water ˇ÷ nucleus collapses inwardly and the nuclear membrane wrinkles into a series of concavities.
4. Chromatin staining
With degeneration, denaturation of nuclear protein affects its affinity for hematoxylin resulting in either hypochromasia or hyperchormasia.
5. Chromatin-Parachromatin interface blurring
There is smudging or blurring of the normally well defined chromatin-parachromatic interfaces.
6. Chromatin clumping
As the chromatin degenerates, it becomes sticky, cohering together with larger aggregates of degenerated chromatinic clumps.
Morphologic effects on cells of progressive processes resulting in increased activity ˇV Proplasia
There are many processes such as stimulation, repair and replication that can act upon cells with resulting increased general activity.
1. Nuclear membrane undulation
With increased cellular activity, the nuclear membrane is thrown into waves or undulation.
Chromatin becomes more hyperchromatic with increased cellular activity.
As biologically inactive heterochromatin moves out of the parachromatin and condenses into the chromatin net and rim, the parachromatin becomes bypochromatic or cleared.
As a response to a great demand for protein synthesis with increased activity, the nucleolus can enlarge, multiply and become prominent. The nucleoli however remain round without sharply pointed angles.
5. Mitosis and multinucleation
Rapidly growing cells exhibit many mitosis and considerable multinucleation. Multinucleation in simple proplasia is characterized by the predictability of one nucleus to another rather than the non predictability of cancer.
6. Relationships of nucleus to cytoplasm
There is greater immaturity to the cytoplasm of the cell with increased activity. Also, the amount of cytoplasm decreases relative to the nucleoplasm, resulting in an increase in the N/C ratio.
Morphologic effects on cells of processes associated with classic invasive cancer ˇV Malignant criteria
1. General philosophy
- There is no perfect or absolute morphologic feature of cancer. A few key morphologic changes occur, however, that signify a high likelihood of cancer being present.
- Malignancy can only be diagnosed on well preserved cells.
- Four major basic thoughts run through the malignant criteria, they are:
² Sharp angularity
2. Nucleus (most valuable)
- Pattern is altered and irregular.
- Massive chromatin clumps
² Sharp pointed projection
² Coarsely granular
² Marked hyperchromasia
- Abnormally ˇ§cleared ˇ§ area
- Large, unevenly distributed
(c) Nuclear membrane
- Irregular sharply angled projection into nucleus and into cytoplasm
- Extreme thickness alternating with extreme thinness
- Irregular with sharp projection
- Massive size
- Numbers increased and vary
- Multinucleation (nuclear pattern varies from nucleus to nucleus)
- Abnormal mitosis
Few malignant criteria are found in cytoplasm. It is mainly the site for differentiating characteristics.
Cytoplasm, however, must be present and intact to support an unequivocal diagnosis of cancer.
4. Relationship of nuclear to cytoplasm
Amount relationship ˇV High N/C ratio.
5. Relationship of one cell to another in true tissue fragments
(a) Irregularity and variability when comparing ˇ§siblingˇ¨ cells in the same piece of tissue.
E.g. Nuclear ˇV great variability in chromatin pattern, size, shape, polarity.
Cytoplasm ˇV variability in amount, cell to cell.
(b) Formation of tissue ˇ§organellesˇ¨ foreign to the area.
E.g. Formation of acini, polyps, syncytia, etc.