AgNOR technique could be useful for differential diagnosis of squamous carcinomatous cells and atypical cells related to human papillomavirus in cervical smears.

The human papillomavirus (HPV)-associated effect can mimic invasive squamous cell carcinoma. Measurements of the argyrophilic nucleolar organizer region (AgNOR) area of cells from smears with HPV infection of the cervix with marked atypia were carried out to differentiate this pathology from keratinizing carcinomas. After destaining, the smears were incubated in the dark for 25 min with a mixture of silver nitrate and gelatin in formic acid. After washing with deionized water and sodium thiosulfate, the slides were dehydrated and mounted with Canada balsam. The average AgNOR area was determined by image cytometry using the immersion oil objective and selecting 100 cells in each smear. Twenty-three patients with a mean AgNOR area of 1.32 microm(2) among their samples showed normal colposcopies and cervical smears after 18 months. In four patients, whose samples were diagnosed as atypical squamous cells of undetermined significance with viral atypia, the average AgNOR area was 7.70 microm(2); biopsies showed keratinizing squamous carcinomas in three of these cases and moderately differentiated squamous carcinoma in one of them. We propose a cutoff of 2.2 microm(2) for the AgNOR area of cells from smears with HPV infection of the cervix with marked atypia to differentiate this group from keratinizing carcinomas.