Cervical dysplasia is the abnormal growth of cells on the surface of the cervix, the opening of the uterus that leads into the vagina. Cervical dysplasia is not cancer. Rather, it is a precancerous condition that may develop into cervical cancer if left untreated. Cervical dysplasia is also called cervical intraepithelial neoplasia (CIN) or squamous intraepithelial lesion (SIL).

Viruses or other cancer-causing agents may cause cervical cells to grow abnormally. When this occurs, the cells are considered to have dysplasia. In the early stages, these cells stay within the surface lining of the cervix. At this point, the condition is confined to the surface layer and it is easy to detect and treat. If left untreated, however, the abnormal cells may invade deeper tissue. This is called invasive cancer.

A group of abnormal cells is called a lesion. Cervical dysplasia lesions can:

• Shrink or disappear
• Remain without changing
• Progress to become cervical cancer

Cervical dysplasia can occur at any time after puberty, but it is most common in women ages 25 to 35 years. With early identification, treatment and follow-up, nearly all cases of cervical dysplasia can be cured but the condition can recur. Without treatment, 30 to 50 percent of cervical dysplasias may progress to invasive cancer, according to the National Institutes of Health.

Cervical dysplasia is classified according to the results of a Pap smear. Physicians may use three different systems to classify results of Pap smears: the descriptive system, the CIN system or the Bethesda system. The main difference between these classification systems is whether numbers or words are used to describe the extent of dysplasia. The systems include:

Other terms that may be used to describe cervical dysplasia include:

• Regressive. Referring to cells that shrink or disappear.
• Persistent. Referring to cells that remain present but do not change.
• Progressive. Referring to cells that become cancerous.

If a woman is confused by the classification system used by her physician, she should request clarification of the information.