Koilocyte

[
pap smear with group of normal cervical cells on left and HPV-infected cells showing features typical of koilocytes: enlarged (x2 or x3) nuclei and hyperchromasia.]

Koilocytes are a type of dysplastic squamous cell found in potentially precancerous cervical lesions. They have the following characteristics:

*Nuclear enlargement (two to three times normal size)
*Irregularity in the nuclear contour (occasionally)
*Hyperchromasia(occasionally)
*Perinuclear clearing

Koilocytosis (a.k.a koilocytotic atypia) are cellular changes in which cells appear to have halo nuclei on cytologic examination. Histologic review usually reveals an abnormal lesion composed of intermediate and superficial squamous cells of the vaginal epithelium. Koilocytosis is characteristic of ASC-US (atypical squamous cells - undetermined significance) by cytologists if the degree of koilocytosis appears minute. A more differentiated koilocyte, possessing a more hyperchromatic and enlarged nucleus, and a higher degree of cytoplasmic clearing with a discernible peripheral rim favor an interpretation of low-grade squamous intraepithelial lesion (LSIL). These changes occur in the presence of human papillomavirus, and occasionally can lead to cervical intraepithelial neoplasia, and eventually malignant cancer.

ee Also

Human papillomavirus