Cervical intraepithelial neoplasia (CIN) I represent minimal (mild) dysplasia (low-grade squamous intraepithelial lesion, or LSIL) and is a potentially reversible process. Dysplasia is preneoplastic and may progress to carcinomas if not treated. Risk factors for cervical dysplasia and carcinoma include early age at first intercourse, multiple sexual partners, and a male partner with multiple previous sexual partners. These factors all increase the potential for infection with human papillomavirus. Diethylstilbestrol (DES) exposure is a factor in the development of clear cell carcinomas of the vagina and cervix. The use of oral contraceptives, which contain very low amounts of hormonally active compounds, does not cause cervical dysplasia or carcinoma. Treatment of cancers does not typically result in dysplasia, although the atypical changes in epithelial cells from radiation and/or chemotherapy may be challenging to distinguish from cancer. A vitamin B12 deficiency may produce some megaloblastic epithelial changes, but not dysplasia.