Cervical intraepithelial neoplasia

Cervical intraepithelial neoplasia
Other names	Cervical dysplasia
Positive visual inspection with acetic acid of the cervix for CIN-1
Specialty	Gynecology

Cervical intraepithelial neoplasia (CIN), also known as cervical dysplasia, is the abnormal growth of cells on the surface of the cervix that could potentially lead to cervical cancer.^[1] More specifically, CIN refers to the potentially precancerous transformation of cells of the cervix.

CIN most commonly occurs at the squamocolumnar junction of the cervix, a transitional area between the squamous epithelium of the vagina and the columnar epithelium of the endocervix.^[2] It can also occur in vaginal walls and vulvar epithelium. CIN is graded on a 1–3 scale, with 3 being the most abnormal (see classification section below).

Human papillomavirus (HPV) infection is necessary for the development of CIN, but not all with this infection develop cervical cancer.^[3] Many women with HPV infection never develop CIN or cervical cancer. Typically, HPV resolves on its own.^[4] However, those with an HPV infection that lasts more than one or two years have a higher risk of developing a higher grade of CIN.^[5]

Like other intraepithelial neoplasias, CIN is not cancer and is usually curable.^[3] Most cases of CIN either remain stable or are eliminated by the person's immune system without need for intervention. However, a small percentage of cases progress to cervical cancer, typically cervical squamous cell carcinoma (SCC), if left untreated.^[6]