Low grade squamous intraepithelial lesion (LSIL)
This article was last reviewed and updated on October 8, 2018
by Jason Wasserman, MD PhD FRCPC
Low grade squamous intraepithelial lesion (LSIL) is a non-cancerous condition that develops in the cervix.
LSIL is caused by a virus called human papillomavirus (HPV) which infects cells on the surface of the cervix.
LSIL can turn into a cancer over time although the risk is very low.
The normal cervix
The cervix is part of the female genital tract. It is found at the bottom of the uterus where it forms an opening into the endometrial cavity. The cervix is lined by special cells called squamous cells that form a barrier on the surface of the cervix called an epithelium.
What is low grade squamous intraepithelial lesion (LSIL)?
Low grade squamous intraepithelial lesion (LSIL) is a non-cancerous disease that develops from the squamous cells on the surface of the cervix. LSIL is caused by a virus called human papillomavirus (HPV) that infects the squamous cells. Once inside the cell, HPV changes the cell and prevents it from developing normally. Pathologists call this change dysplasia.
Although LSIL is considered non-cancerous disease, there is a very small risk that it will turn into a cancer over time. However, for most patients with LSIL, the immune system will remove the infected cells and the cervix will return to normal.
The specific HPV virus associated with LSIL is typically a low risk type of HPV. Cells infected with low risk HPV are much larger than normal squamous cells and are called koilocytes.
The diagnosis of LSIL is usually made after a small sample of tissue is removed in a pap smear or a procedure called a biopsy. A larger biopsy may be performed later to look for a related but more serious condition called high grade intraepithelial lesion (HSIL) or squamous cell carcinoma.