Attributing oncogenic human papillomavirus genotypes to high-grade cervical neoplasia: which type causes the lesion?

Human papillomavirus (HPV) is found in most women with high-grade cervical intraepithelial neoplasia (CIN) 2/3 in cervical cytology and biopsies. Multiple high-risk HPV (hrHPV) genotypes are present in 15% to 50% of cytology samples. We have shown by laser-capture microscopy (LCM)-polymerase chain reaction (PCR) that each lesion is associated with a single hrHPV type. Attribution of hrHPV types to CIN2/3 is important to understand the oncogenic role of different types and the limitations of cytologic typing. We studied hrHPV genotypes in 257 women with histologic CIN2/3 referred on the basis of abnormal cytology. HPV typing was done on cytology and CIN2/3 biopsies. If the whole-tissue section of the biopsy was positive for multiple hrHPV types, LCM-PCR was performed. We found 181 (70%) single and 71 (28%) multiple hrHPV infections in cytology, with 5 (2%) cases HPV-positive only on whole-tissue section PCR. Of cases with multiple cytologic hrHPV infections, 47/71 (66%) showed a single type in CIN2/3 lesions. In total, in 232 of 257 (90%) women with CIN2/3, a single hrHPV type caused CIN2/3. One was nonattributable on the LCM level. The remaining 24 women had 2 or more contiguous or separated lesions, each associated with a single hrHPV infection. The probability of HPV16 being present in CIN2/3, if detected in cytology, was 0.96 (95% confidence interval=0.90-0.98). LCM-PCR confirms that only 9% of histologic CIN2/3 is associated with multiple hrHPV types, much less than cytology would indicate, and each lesion was associated with a single hrHPV infection.