What is a Squamous Intraepithelial Lesion?

The cervix, part of the reproductive system in women, is mostly located on the lower section of the uterus and at the end of the vaginal canal. In the cervix's surface are different types of cells. Abnormal changes in the growth of these cells is usually referred to as a squamous intraepithelial lesion (SIL). This squamous intraepithelial lesion, also called a cervical intraepithelial neoplasia (CIN), is often detected through a screening test called Papaniculao test, or Pap smear. It is often considered a precancerous growth, which means that it has a tendency to become malignant.

An obstetrician/gynecologist (OB/GYN) is a doctor who specializes in pregnancy and women's reproductive tract disorders. He usually performs a Pap smear by taking cell samples from the woman's cervix. These samples are then sent to the laboratory for processing and for the detection of any abnormality. When the pathologist, a doctor who is an expert in analyzing tissues under the microscope, finds a squamous intraepithelial lesion, he usually categorizes this as either a high-grade or a low-grade lesion.

A low-grade squamous intraepithelial lesion is often an indication that there are a few abnormal changes that have started to develop in the cervix. These changes may involve some alterations in the size or the shape of the cervix cells, but they are still often normal in appearance. A woman with a low-grade squamous intraepithelial lesion may be treated in several ways. The doctor may advise the removal of the precancerous cells as soon as possible. Some may recommend monitoring of the patient after several months, with further treatment depending on the woman's follow-up Pap smear results.

If the Pap smear test shows a high-grade squamous intraepithelial lesion, the changes in the cells are said to be very abnormal but are still only present in the cervix's surface. This lesion's probability of becoming cancerous is, however, higher compared to the low-grade squamous intraepithelial lesion. Most women with this diagnosis are advised to undergo a colposcopy. A colposcopy is commonly done by inserting an instrument in the vagina to visualize the cervix and to remove the precancerous cells. It is often a short and painless procedure.

One of the common causes for the development of squamous intraepithelial lesion is infection with the human papillomavirus (HPV). An HPV infection frequently leads to the formation of warts in the genital area. This virus is generally transmitted through sexual intercourse with infected individuals. Individuals who engaged in sex at a young age and those who have many sex partners are at high risk for this infection.