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Squamous Intraepithelial Lesion (SIL)

Squamous Intraepithelial Lesion (SIL) is the abnormal growth of squamous cells on the surface of the cervix.

The cervix is the lower part of the uterus. Both the uterus and the cervix are located in the pelvis and are close to the upper part of the vagina and the ovaries. In fact, the cervix connects the uterus and the vagina. The vagina leads to the outside of the body.

The surface of the cervix is made up of two different types of cells:

  • squamous epithelial cells (the lining cells of the outer part of the cervix, or ectocervix)
  • columnar epithelial cells (the lining cells of the inner part of the cervix, or endocervix)

Early detection and treatment of precancerous cells can prevent them from becoming cancerous. Otherwise, the abnormal cells can become cancer and spread to other parts of the body.

Pap tests

Pap tests can detect precancerous and cancerous conditions by collecting cells from the surface of the cervix. Sometimes these cells appear abnormal, or atypical, when looked at under a microscope, but they are not completely cancerous. These are called premalignant or precancerous cells, which means they might turn into cancer if not found and treated early enough.

These precancerous lesions are commonly called cervical intraepithelial neoplasia (CIN). They have also been called squamous intraepithelial lesions (SIL) and there are two types:

Low-grade SIL - the changes are thought to be just starting. The changes can be in the size, shape, or number of cells that are on the surface of the cervix. In these low-grade lesions, the cells have only a few abnormal characteristics, but are still somewhat similar to the normal cells. Other common names for this low-grade SIL are mild dysplasia or cervical intraepithelial neoplasia type I (CIN 1).

High-grade SIL - the cells look very abnormal under the microscope. However, these cells are still only on the surface of the cervix. They are not invading the deepest parts of the cervix yet. These lesions are also called moderate or severe dysplasia, CIN II or III or carcinoma in situ (CIS).

Please note: Carcinoma in Situ is a term used for the early stage of cancer in which the tumor is confined to the organ where it first developed. The disease has not invaded other parts of the organ or spread to distant parts of the body. Most in situ carcinomas are highly curable. SIL can also be considered a carcinoma in Situ.

Treatment Options for Squamous Intraepithelial Lesion (SIL)

Women diagnosed with SIL are seen in our Multidisciplinary Gynecologic Oncology Clinic. Learn more about the clinic by visiting the Multidiscipinary Gynecologic Oncology Clinic webpage. For women diagnosed with abnormal Pap smears, vaginal intraepithelial neoplasia, squamous intraepithelial lesion, carcinoma in situ, condyloma (genital warts) or human papilloma virus (HPV), we offer our Colposcopy Clinic. Learn more about this clinic by visiting the Colposcopy Clinic webpage.

Or, call 734-647-8906 to make an appointment with either clinic.

Still have questions?

The nurses at Cancer AnswerLine™ have answers. Call 1-800-865-1125 and you'll get a personal response from one of our registered nurses, who have years of experience in caring for people with cancer.

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Cervical Cancer Screening Resources

going to a new websiteNational Breast and Cervical Cancer Early Detection Program (NBCCEDP)
this program provides low-income, uninsured, and underserved women access to timely breast and cervical cancer screening and diagnostic services.