Cytologic features of high-grade squamous intraepithelial lesion in conventional slides: what is the difference between cases that perform well and those that perform poorly?

Context: Previous studies have suggested that cases of high-grade squamous intraepithelial lesion in conventional smears and in ThinPrep specimens that are frequently misinterpreted as normal have relatively few small and hypochromatic dysplastic cells.

Objective: To determine the cytologic differences between conventional Papanicolaou slides of high-grade squamous intraepithelial lesion that perform poorly and those that perform well.

Design: We compared the cytologic features of 22 cases of conventional smears with high-grade squamous intraepithelial lesion that performed poorly in the College of American Pathologists Interlaboratory Comparison Program in Gynecologic Cytology with 45 cases of conventional smears that performed extremely well.

Results: Cases that performed poorly were significantly more likely to have 50 or fewer single dysplastic cells (P = .003) and to have only small dysplastic cells (P = .01). Cases that performed well were also more likely to have more than 500 dysplastic cells (P = .002), to exhibit the presence of large dysplastic cells (P < .001), and to be keratinized (P = .03). Hypochromasia and the number of groups of dysplastic cells were not correlated with performance.

Conclusions: Conventional smears with high-grade squamous intraepithelial lesion with 50 or fewer single dysplastic cells, no large dysplastic cells, and lacking keratinization are highly associated with poor performance in this program.