Atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion: diagnostic performance, human papillomavirus testing, and follow-up results.

BACKGROUND: Current guidelines recommend colposcopy rather than high-risk human papillomavirus (HPV) testing for the evaluation of abnormal cervical cytology interpreted as "atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion" (ASC-H) based on data from the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion (ASCUS/LSIL) Triage Study (ALTS), which indicated that ASC-H had a significantly greater frequency of high-risk HPV positivity and underlying high-grade squamous intraepithelial lesions (HSIL) compared with ASCUS. The cytologic interpretations in the ALTS were expert consensus diagnoses rather than routine, single-pathologist readings.

METHODS: The authors conducted a comparative analysis of Hybrid Capture 2 high-risk HPV positivity and frequency of histologically diagnosed HSIL for ASC-H and ASCUS to evaluate the performance of ASC-H as a cytologic interpretation subcategory and the potential utility of HPV testing for colposcopy triage of ASC-H in routine practice.

RESULTS: Sixty-four of 96 patients with ASC-H (66.7%) were HPV-positive compared with 484 of 1079 patients with ASCUS (44.9%). Among the patients who had histologic follow-up, HSIL was identified in 18 of 45 patients (40.0%) with HPV-positive ASC-H compared with 27 of 266 patients (10.2%) with HPV-positive ASCUS (P < 0.0001) and 1 of 22 patients (4.5%) with HPV-negative ASC-H (P = 0.003); the latter result was similar to the finding of HSIL in 5 of 85 patients (5.9%) with HPV-negative ASCUS. The frequency of HPV-positive ASC-H in the current study (67%) was lower than that obtained in the ALTS for ASC-H (86%) but higher than that for ASCUS in both this study (45%) and in the ALTS (51% for all ASC; 63% for ASCUS, equivocal for LSIL). Underlying HSIL was detected in a similar percentage of patients with HPV-positive ASC-H in this study and in the ALTS (41%).

CONCLUSIONS: The greater frequency of HPV positivity and the significantly increased risk of underlying HSIL for ASC-H compared with ASCUS indicated that ASC-H category utilization and performance are appropriate in this routine clinical practice setting. The lower frequency of HPV positivity for ASC-H compared with the ALTS data and the similar low risk of HSIL in HPV-negative ASC-H and HPV-negative ASCUS indicate that HPV testing for triage of ASC-H in routine practice has the potential to reduce the number of women who are referred for colposcopy without an increased risk of failure to detect HSIL among HPV-negative women, similar to its triage role for ASCUS.