Human papillomavirus typing and DNA ploidy determination of squamous intraepithelial lesions in liquid-based cytologic samples.

BACKGROUND

Infection by high-risk human papillomavirus (HPV) plays a role in the evolution of cervical carcinoma. Cellular atypia and consecutive DNA content alterations in cytologic samples are consequences of a preexisting viral infection.

METHODS

We analyzed the frequency and association of HPV types and the presence of rare cells with abnormally high DNA content. We also evaluated whether these findings support the cytologic diagnosis in 112 routine cases with low and high-grade squamous intraepithelial lesions (LSIL/HSIL) when performed from liquid-based cytologic samples (ThinPrep). For DNA content measurements, laser scanning cytometry was applied and at least 10,000 cells were analyzed. HPV typing was performed by a direct sequencing approach using the consensus primers GP5+/GP6+ and MY09/MY11.

RESULTS

Of 112 SIL cases, 110 (98.2%) were HPV positive and 95 (84.8%) had a high-risk type HPV infection. Almost one-half of the cases (46 of 95, 48.4%) with a high-risk HPV infection presented aneuploid squamous cells with greater than 9c DNA content, whereas none of the low-risk HPV-positive or HPV-negative SIL cases showed any aneuploid cells in this range. Although 91.8% of the HSIL cases displayed greater than 9c aneuploid cells, only 7.9% of the LSIL cases were positive for such cells with abnormally high DNA content.

CONCLUSIONS

HPV typing and DNA measurements help in the objectivation of cytologic atypia and both can be performed efficiently from the same liquid-based cytologic samples.