Cervical dysplasia refers to the presence of precancerous changes of the cells that make up the surface of the cervix, the opening to the womb (uterus). The term dysplasia refers to the abnormal appearance of the cells when viewed under the microscope. The degree and extent of abnormality seen on a tissue sample biopsy was formerly referred to as mild, moderate, or severe dysplasia. In recent years, this nomenclature has been replaced by a newer system. These systems are based upon changes in the appearance of cells visualized when smears of individual cells (cytological changes) or tissue biopsies (histological changes) are reviewed under a microscope. Pap smears obtain samples of the surface cells to determine if they are normal or abnormal and do not provide a diagnosis, which can only be done by a tissue biopsy.
- Pap smears are described according to the degree of abnormality: ASCUS (atypical squamous cells of uncertain significance), LSIL (low grade squamous intraepithelial lesion) and HSIL (high grade squamous intraepithelial lesion. Cells from glandular rather than squamous epithelium may also be described.
- Cervical intraepithelial neoplasia (CIN) is cervical dysplasia that is a pathological diagnosis based on a cervical biopsy or surgically removed cervix. This is indicated by CIN1 (mild), CIN2 (moderate), CIN III (severe). These are all precancerous conditions.
These classification systems will be further discussed below.
Are there signs and symptoms of cervical dysplasia?
Typically, cervical dysplasia does not produce any signs or symptoms. So regular Pap smear screening is important for early diagnosis and treatment.
How is cervical dysplasia diagnosed?
Screening for cervical dysplasia
Cervical dysplasia and cervical cancer generally develop over a period of years, so regular screening is essential to detect and treat early precancerous changes and prevent cervical cancer. Traditionally, the Papanicolaou test (Pap test or Pap smear) has been the screening method of choice. To perform the Pap smear, the health care practitioner removes a swab or brush sample of cells from the outside of the cervix during a pelvic examination using a speculum in the vagina for visualization. The cells are smeared onto a glass slide, stained, and observed under the microscope for any evidence of abnormal cells.
Newer, liquid-based systems to screen samples of cervical cells are now much more common and are effective screening tools for detection of abnormal cells. The samples for this test are obtained the same way as for the conventional Pap smear, but the sample is placed in a vial of liquid that is later used to prepare a microscope slide for examination as with the Pap smear.
For women whose initial screening result is unclear or abnormal, other diagnostic tests are used:
- Colposcopy is a gynecological procedure that illuminates and magnifies the vulva, vaginal walls, and uterine cervix in order to detect and examine abnormalities of these structures. A colposcope is a microscope that resembles a pair of binoculars. The instrument has a range of magnification lenses. It also has color filters that allow the physician to detect surface abnormalities of the cervix, vagina and vulva.
- A Biopsy is a tissue sample obtained for examination under the microscope. A biopsy is taken from suspicious surface areas seen during colposcopy. A diagnosis can only be made from a tissue biopsy.
- HPV testing to detect a "high-risk" type is done if a Pap smear is abnormal or may be recommended for some women. Use of HPV testing alone is being suggested as a replacement for the Pap smear.
How is cervical dysplasia classified?
Cytologic analysis (screening tests)
Pap smear reports are based on a medical terminology system called The Bethesda System that was developed at the National Institutes of Health (NIH) in Bethesda, Maryland in 1988 and modified in 2001. The major categories for abnormal Pap smears reported in the Bethesda Systems are as follows:
- ASC-US: This abbreviation stands for atypical squamous cells of undetermined significance. The word "squamous" describes the thin, flat cells that lie on the surface of the cervix. One of two choices are added at the end of ASC: ASC-US, which means undetermined significance, or ASC-H, which means cannot exclude HSIL (see below).
- LSIL: This abbreviation stands for low-grade squamous intraepithelial lesion. This means changes characteristic of mild dysplasia are observed in the cervical cells.
- HSIL: This abbreviation stands for high-grade squamous intraepithelial lesion. And refers to the fact that cells with a severe degree of dysplasia are seen.
Histologic analysis (cervical biopsies)
When precancerous changes are seen in tissue biopsies of the cervix, the term cervical intraepithelial neoplasia (CIN) is used. "Intraepithelial" refers to the fact that the abnormal cells are present within the lining, or epithelial, tissue of the cervix. "Neoplasia" refers to the abnormal growth of cells.
CIN is classified according to the extent to which the abnormal, or dysplastic, cells are seen in the cervical lining tissue:
- CIN 1 refers to the presence of dysplasia confined to the basal third of the cervical lining, or epithelium (formerly called mild dysplasia). This is considered to be a low-grade lesion.
- CIN 2 is considered to be a high-grade lesion. It refers to dysplastic cellular changes confined to the basal two-thirds of the lining tissue (formerly called moderate dysplasia).
- CIN 3 is also a high grade lesion. It refers to precancerous changes in the cells encompassing greater than two-thirds of the cervical lining thickness, including full-thickness lesions that were formerly referred to as severe dysplasia and carcinoma in situ.