High grade squamous intraepithelial lesion (HSIL) of the vagina

by Emily Goebel, MD FRCPC
June 6, 2022

What is high grade squamous intraepithelial lesion (HSIL) of the vagina?

High grade squamous intraepithelial lesion (HSIL) of the vagina is a pre-cancerous, sexually transmitted disease caused by infection with human papillomavirus (HPV). This condition may affect both women and men. In addition to the vagina, HSIL commonly involves the cervix and vulva. In both women and men, HSIL may also involve the anal canal and peri-anal skin.

What causes high grade squamous intraepithelial lesion in the vagina?

HSIL in the vagina is caused by human papillomavirus (HPV). The virus infects the specialized squamous cells on the inside surface of the vagina which leads to an abnormal pattern of development called dysplasia.

Is high grade squamous intraepithelial lesion of the vagina a type of cancer?

HSIL of the vagina is not cancer although patients with HSIL are at increased risk for developing a type of vaginal cancer called squamous cell carcinoma. For this reason, most patients with HSIL are offered treatment to remove the area of abnormal tissue. Low-grade squamous intraepithelial lesion (LSIL) is a related condition that is also caused by HPV. However, compared to HSIL, the risk of developing cancer from LSIL is much lower.

How is the diagnosis of high grade squamous intraepithelial lesion of the vagina made?

The diagnosis of HSIL in the vagina is usually made after a small sample of tissue is removed in a procedure called a biopsy. A larger surgical procedure, for example, an excision or vaginectomy, is later performed to remove the disease and look for abnormal cells in the lamina propria.

What is p16 and why is it important?

Cells infected with high-risk types of human papillomavirus (HPV) produce large amounts of a protein called p16. Your pathologist may perform a test called immunohistochemistry to look for p16 inside the abnormal cells. This will confirm the diagnosis of HSIL and rule out other conditions that can look like HSIL under the microscope. Almost all cases of HSIL are positive or reactive for p16 which means your pathologist saw the p16 protein in the abnormal cells.

What is a margin?

A margin is any tissue that has to be cut by the surgeon in order to remove the tumour from your body. A negative margin means that no HSIL cells were seen at the cut edge of the tissue. In contrast, a positive margin means that HSIL cells were seen at the cut edge of the tissue. A positive margin increases the risk that the tumour will grow back in that location.