Postmenopausal Squamous Atypia: Cytologic Features, Hybrid Capture 2 Tests and Contribution to the ASCUS Pool

OBJECTIVE: Postmenopausal squamous atypia (PSA) mimics squamous intraepithelial lesion (SIL). We investigate the PSA contribution to the atypical squamous cells of undetermined significance (ASCUS) pool, its cytologic features and Hybrid Capture 2 (HC2) relative light unit/cutoff (RLU/CO) values. STUDY DESIGN: 658 ASCUS Pap tests in women ≥55 years were reviewed to select those with koilocyte-like cells and/or atypical parakeratosis. Follow-up was positive when a biopsy showed SIL or carcinoma or a later HC2 test was positive. RESULTS: Sixty-nine cases (10.5%) were selected. Forty-two (60.9%) were HC2 negative, and 27 (39.1%) were HC2 positive. Follow-up was available for 23 (54.7%) HC2-negative and 19 (70.3%) HC2-positive cases. No HC2-negative (0%) and 8 HC2-positive (42.1%) cases were positive on follow-up. Within cases negative on follow-up, 3 were PSA on biopsy. PSA was characterized by perinuclear halos, mild nuclear enlargement, smooth nuclear contours, and smooth chromatin. PSA-associated RLU/CO values were 0.25-2.95. Cases with SIL or carcinoma had RLU/CO values from 3.78 to 1,241.59. CONCLUSIONS: PSA contributes 0.5-2.3% to the ASCUS pool in women ≥55 years old. HC2 testing with RLU/CO of ≥1 may result in PSA occasionally testing positive. A different cutoff is not recommended but awareness of this caveat is important.