CIN3

Cervical intraepithelial neoplasia grade 3 (CIN3) is the most advanced form of cervical intraepithelial neoplasia, representing high-grade dysplasia that involves the full thickness of the squamous epithelium but does not invade the underlying basement membrane. In many classifications CIN3 corresponds to a high-grade squamous intraepithelial lesion (HSIL) on cytology.

CIN3 is commonly associated with persistent infection by high-risk human papillomavirus (HPV), particularly HPV types 16 and 18. Risk factors for developing CIN3 include smoking, immunosuppression (such as HIV infection), and sexual and reproductive factors like younger age at first intercourse or multiple sexual partners. The condition often arises after a transition from lower-grade lesions and may persist for years if not treated.

Diagnosis typically starts with cervical screening using cytology, which may indicate HSIL. Confirmation requires colposcopic examination with directed biopsy and histopathological assessment showing full-thickness dysplasia without invasion. Immunohistochemical staining for p16INK4a can support the diagnosis and HPV testing is usually positive for high-risk types.

Management aims to remove or destroy the affected tissue and prevent progression to invasive cancer. Excisional procedures such as loop electrosurgical excision procedure (LEEP) or cold knife conization are commonly used in non-pregnant patients, while ablative methods may be considered in select cases. In pregnancy, treatment is often deferred until after delivery unless invasive cancer is suspected. Post-treatment follow-up includes periodic cytology and HPV testing to monitor for recurrence.

Prognosis after appropriate treatment is favorable, with high cure rates, though recurrence can occur and ongoing surveillance is recommended.