What is a High-Grade Squamous Intraepithelial Lesion?

A high-grade squamous intraepithelial lesion, also called HSIL or HGSIL, is an abnormal growth of cells on the cervix. These cells are found in a Pap smear. The presence of HSIL is often linked to cervical cancer. The diagnosis usually indicates the need for further testing to asses the potential cancer risk.

A Pap smear is part of a gynecological pelvic examination where the doctor scrapes a small amount of tissue off the surface of the cervix. The cells are examined under a microscope in a laboratory, where a technician looks at the size and shape of the cells. A diagnosis of a low-grade squamous intraepithelial lesion, or LSIL indicates that there is a small amount of abnormal cells and that not much of the cervix is affected. A high-grade squamous intraepithelial lesion indicates a large number of very abnormal cells covering much of the cervix.

A LSIL diagnosis might call for another Pap smear in the near future to check for further cell changes. Often a LSIL result can be a false positive caused by menstruation, an infection, or other foreign material on the cervix such as male ejaculate or douching liquid. A diagnosis of HSIL usually calls for further evaluation immediately, as these have the highest chance of turning into cancer.

Usually, a doctor further examines a high-grade squamous intraepithelial lesion by doing a colposcopy. This procedure is similar to a pelvic exam, but uses an instrument similar to a small microscope that magnifies the cells to ten times their normal size. The extent of the abnormalities are evaluated, and the doctor also looks for changes in the cervical capillaries, which isn't checked in a Pap smear.

During the cervical colposcopy, the doctor might also remove a sample of tissue in a procedure called a biopsy. A cervical biopsy is generally uncomfortable, but not painful enough to require local or general anesthetics. The tissue sample is more closely examined for pre-cancerous changes. In many cases, pre-cancerous cells can be removed by freezing or cutterage.

For most women, an abnormal Pap result is extremely upsetting. However, the diagnosis of a high-grade squamous intraepithelial lesion is found to be cancer in fewer than two percent of cases. It is important to follow-up the diagnosis however, because 20 percent of of women with HSIL develop cancer in the future. Aside from the colposcopy and biopsy, more frequent Pap tests are usually ordered to monitor for changes.