A precancerous neoplastic process that affects the cervical squamous epithelium. It is usually associated with human papillomavirus infection. It is classified as cervical squamous intraepithelial neoplasia 2 when there is nuclear atypia in both the upper and lower epithelial layers, mitotic figures are confined to the basal two-thirds of the epithelium, and maturation is present in the upper half of the epithelium. It is classified as cervical squamous intraepithelial neoplasia 3 when there is nuclear atypia and mitotic figures throughout the entire thickness of the epithelium, and maturation is absent or confined to the upper third of the epithelium. [from
NCI]