koilocytosis

Koilocytosis is the presence of koilocytes, squamous epithelial cells that show a characteristic cytopathic effect caused by human papillomavirus (HPV) infection. Koilocytes have a large, irregular, hyperchromatic nucleus often described as raisinoid, surrounded by a clear perinuclear halo and a vacuolated, pale cytoplasm. These changes are most evident in the upper layers of stratified squamous epithelium, such as the epithelium of the cervix, anogenital mucosa, or oral mucosa.

Etiology and significance

The cytopathic changes occur as HPV infects squamous cells and alters their differentiation. Koilocytosis is most commonly associated with HPV infections, including low-risk types (for example, 6 and 11, which can cause condylomas) and high-risk types (such as 16 and 18, which are linked to cervical intraepithelial neoplasia and cancer). The finding itself indicates HPV exposure and infection rather than malignancy, though extensive koilocytosis can be seen in lesions that require further assessment for dysplasia or neoplasia.

Clinical context

Koilocytosis is frequently identified on cervical cytology (Pap tests) and can be observed in biopsy specimens from genital warts and HPV-related lesions in other sites. Its presence supports HPV-related pathology and prompts appropriate follow-up, including HPV typing and consideration of lesion severity. Management focuses on monitoring and treating HPV-associated lesions as indicated, along with vaccination strategies to reduce HPV-related disease.