by Jason Wasserman MD PhD FRCPC
June 3, 2022

What are koilocytes?

Koilocytes are a type of cell called squamous cells that have been infected by human papillomavirus (HPV). Koilocytes are commonly seen in conditions caused by HPV including low grade squamous intraepithelial lesion (LSIL) and high grade squamous intraepithelial lesion (HSIL).

What do koilocytes look like under the microscope?

When examined under the microscope have larger and darker nuclei than normal squamous cells and the nucleus (the part of the cell that holds the genetic material) is often surrounded by a white space called a halo. Pathologists sometimes use the terms koilocytosis, koilocytic change, or koilocytic atypia to describe a group of koilocytes.


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