Cervix, High-grade squamous intraepithelial lesion, p16 stain

High‐grade squamous intraepithelial lesions (HSILs) of the cervix are precursors of invasive cervical cancer (squamous cell carcinoma). The current HSIL classification corresponds to the older histological classification of CIN (cervical intraepithelial neoplasia) 2 or 3. In this case, HSIL is present incidentally within an endocervical polyp—an uncommon presentation.

Sections show an endocervical polyp with focal gland involvement by high grade squamous intraepithelial neoplasia (CIN 3). Involved areas show crowded squamous cells with enlarged, hyperchromatic and pleomorphic nuclei occupying the entire thickness of the epithelium. Mitoses are high and there is single-cell necrosis. Immunohistochemical staining shows strong, full thickness p16 reactivity and high Ki-67 proliferative index, further supporting the diagnosis of high grade cervical intraepithelial neoplasia.