Case 142. HPV-6 infection (condyloma acuminatum) (22 y-o F)
    Cervical smear and biopsy from a sexually active woman with polypoid lesions in the uterine cervix    
Key words : human papillomavirus, condyloma acuminatum, koilocytosis
sexually transmitted infection
Koilocytosis is seen in the superficial-type squamous cells with mild nuclear enlargement (Papanicolaou). The features represent condyloma acuminatum.   The polypoid lesion consists of papillomatosis of non-keratinizing squamous epithelium. Koilocytosis with perinuclear haloe is seen in the superficial layer (HE).
Many nuclei are positively stained with cocktail probes to HPV, type 6/11 (non-isotopic in situ hybridization).   Consecutive sectioning discloses that HPV antigen-positive nuclei are much less than the HPV 6/11 genome-positive nuclei (immunostaining using a rabbit antiserum to common capsid antigen).
HPV, type 6/11 genome-positive nucleus was observed at the ultrastructural level. The nucleus of a koilocytic keratinocyte is filled with positive fine particles (pre-embedding method for in situ hybridization using a paraffin section).   HPV, type 6/11 genome-reactive intranuclear particles measure about 20 nm, much smaller than mature HPV viral particles (50-60 nm). Together with the paucity of capsid antigen expression, it is likely that the viral genome is distributed as an episome (naked DNA) in the nucleus.
Reference case 142A
Condyloma acuminatum of the penis (24 y-o M). Multiple papillomatous lesions are formed in the prepuce of the penis (gross findings).