Histologic Findings of HPV Infection Histological findings of HPV infection are quite valuable. Histologic Findings of HPV • Viral multiplication occurs inside the host cell nucleus. • Nuclear atypia in infected cells i.e. a pre-neoplastic, malignant or reactive stage • Presence of abnormal koilocytes; a sign of productive HPV infection • Acanthosis • Multinucleation • Dyskeratosis Koilocytosis in HPV Infection Koilocytosis, also known as koilocytic atypia or koilocytotic atypia, is the presence of koilocytes in a specimen. When a squamous epithelial cell undergoes several structural changes as a result of HPV infection, it is known as koilocyte. It is characteristic histological finding in a suspected specimen of HPV infection. It is a cytopathic effect which includes several cellular changes such as • nuclear enlargement up to 2-3 times the original size • irregular raisinoid appearance of the nuclear membrane • hyperchromasia i.e. dark staining pattern • occurrence of perinuclear halo or cytoplasmic vacuolization.