CIN is the acronym for Cervical Intraepithelial Neoplasia.
CIN means that atypical cells, i.e. those which do not have the typical normal morphology are restricted to the inside of the epithelium (intraepithelial neoplasia).
Milder lesions are characterized as CIN1. In these lesions only the lower third (1/3) of the epithelium is occupied by cells with infectious atypia. CIN1 lesions are caused by both low-risk and oncogenic types of HPV.
The more severe lesions are characterized as CIN2 and, CIN3. In these lesions the lower two-thirds (2/3) or the entire thickness of the epithelium (3/3) respectively, are occupied by neoplastic cells. CIN2 and CIN3 lesions are only caused by oncogenic types of HPV.
CIN3 lesions are characterized as Carcinoma In Situ (CIS) when the entire thickness of the epithelium