Objective: To assess the utility of consensus review of original ThinPrep slides (Cytyc Corp., Boxborough, Masssachusetts) vs. duplicate slides and to identify the significance of the number of representative cells in classifying atypical squamous metaplastic cells, cannot exclude high grade squamous intraepithelial lesion (ASC-H).
Study design: A duplicate ThinPrep slide was prepared from 19 cases of ASC-H. Both original and duplicate slides underwent blinded review by 4 pathologists. Consensus cytologic interpretations (75% agreement) were noted and compared with follow-up diagnoses. Dots with atypical metaplastic cells from each slide were counted and correlated with the consensus cytologic interpretation.
Results: Following review of 19 original and 19 duplicate slides, consensus interpretations were reached in 14 and 15 cases, respectively. Nine cases of squamous intraepithelial lesion (SIL) were confirmed by biopsies. Consensus interpretation of original and duplicate slides predicted 7 and 6 cases of SIL, respectively. Consensus interpretation of duplicate slides predicted 60% of histologically benign cases. Two-thirds of nonconsensus cases were histologically benign. Consensus interpretations for high grade SIL were reached more often on slides with greater numbers of atypical squamous metaplastic cells. Fewer abnormal cells were present on the duplicate slides.
Conclusion: Consensus reviews of original and duplicate slides are equally useful in classifying atypical squamous cells, cannot exclude high grade squamous intraepithelial lesion, but may not be practical in all circumstances. HPV DNA testing of all such cases may better detect clinically significant cases.