Cervix, High grade squamous intraepithelial lesion

Squamous intraepithelial lesion is an early form of cervical cancer caused by HPV, and is the most common pre-malignant abnormality detected on Pap tests. High-risk HPV types are generally associated with high-grade squamous intraepithelial lesions (HSIL). The current HSIL classification corresponds to the older histological classification of CIN (cervical intraepithelial neoplasia) 2 or 3.

Cytologically, the cells are either discrete or present as syncytium-like groups. The cells show increased nuclear-to-cytoplasmic (N:C) ratio, nuclear irregularities, with marked hyperchromasia and coarse chromatin. The differential diagnoses include squamous metaplasia, atrophy, and adenocarcinoma in situ.