A growth on the surface of the cervix with moderately or severely abnormal cells. High-grade squamous intraepithelial lesions are usually caused by certain types of human papillomavirus (HPV) and are found when a Pap test is done. If not treated, these abnormal cells may become cancer and spread to nearby normal tissue. A high-grade squamous intraepithelial lesion is sometimes called moderate or severe dysplasia. Also called HSIL.