Conventional Papanicolaou (Pap) test slides of high-grade squamous intraepithelial lesions (HSILs) that are frequently misdiagnosed are known to have relatively few dysplastic cells. Whether this is true of cases of HSIL in ThinPrep Pap Test specimens is not known.
To determine if cases of HSIL in ThinPrep specimens that are frequently missed have relatively few dysplastic cells.
The cytologic features of 16 ThinPrep cases of HSIL that performed poorly in the College of American Pathologists Interlaboratory Comparison Program were compared with 22 ThinPrep Pap Test cases that performed extremely well.
Significantly more cases that performed poorly had fewer than 250 dysplastic cells (13/16) than cases that performed well (3/22) (P <.001).
ThinPrep Pap Test cases with a diagnosis of HSIL that performed poorly in this program had significantly fewer dysplastic cells than those that performed well.