Koilocyte

These proteins break down keratin in HPV-infected cells, resulting in the perinuclear halo and nuclear enlargement typical of koilocytes.

[5] These stains give the cytoplasm and nuclei of cells characteristic colors and allows for visualization of the nuclear enlargement and irregularity, hyperchromasia, and perinuclear halo that are typical of koilocytes.

In addition, squamous cells commonly display binucleation and mitoses are present, signifying increased cellular division.

[9] However, the current standard of care for these tumors includes verification of HPV status using methodologies other than the histopathologic presence or absence of koilocytes alone.

[10] These methodologies include polymerase chain reaction (PCR), in situ hybridization (ISH), and immunohistochemistry (IHC).

In contrast to LSIL, HSIL in the anus consists of abnormal basaloid cells replacing more than half of the anal epithelium.

[11] These changes occur in the presence of human papillomavirus and occasionally can lead to cervical intraepithelial neoplasia, and if left untreated some may eventually progress to malignant cancer.