Highly squamous intraepithelial lesions (HSIL) are precancerous lesions. Precancerous lesions, in general, are precancerous lesions of the squamous epithelium, also known as intraepithelial neoplasia. Depending on the degree of cellular carcinoma, they can be classified into three levels, mild atypical hyperplasia (CIN grade 1), moderate atypical hyperplasia (CIN grade 2) and severe atypical hyperplasia (CIN grade 3). Highly advanced squamous intraepithelial lesions are defined as moderate atypical hyperplasia, severe atypical hyperplasia, and carcinoma in situ. Treatment of highly squamous intraepithelial lesions is recommended to be surgical. The treatment is determined based on the patient’s cytology as well as biopsy results. Patients with high grade squamous intraepithelial lesions generally have a good prognosis and can be reviewed regularly after surgery.