Simplified diagram of cervical carcinogenesis. The cell of origin infected initially by human papillomavirus (HPV) types influences the manifestation of HPV mediated carcinogenesis. Squamous-type lesions emerge from the cervix squamous-columnar junction (SCU) into low-grade cervical lesions (cervical intraepithelial neoplasia grade 1, CIN1), which may or may not progress to precancerous lesions (cervical intraepithelial neoplasia grade 3, CIN3); alternatively, glandular-type lesions have a poorly detected preinvasive stage (adenocarcinoma in situ, AIS). These lesions will evolve into either squamous cell carcinoma (SCC) or into adenocarcinoma (AC).