This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
Koilocytes with dyskeratosis and perinuclear halo on pap smear is pathognomonic of which of the following? 
Select and explain. 
A. HPV infection, B. Metaplasia, C. Dysplasia, D. Bacterial vaginosis
A: HPV infection
Answer: A: HPV infection 
Explanation: The presence of abnormal koilocytes (keratinocytes with pyknotic, deeply blue nuclei surrounded by a halo and clear cytoplasm with a paucity of keratohyaline granules), or koilocytosis, is a characteristic feature of productive HPV infection. Other cytologic markers of HPV infection include acanthosis, dyskeratosis, and multinucleation. Virus multiplication is confined to the host cell nucleus. Consequently, infected cells exhibit a high degree of nuclear atypia.