Proliferation in “Atypical” Atrophic Pap Smears

Objective. Atrophic cervical epithelium of postmenopausal women may mimic high-grade cervical intraepithelial neoplasia (CIN2–3) in Papanicolaou-stained cervical smears (Pap smears). Women with such an “atypical” Pap smear need a repeated Pap smear after a course of estrogens before a definite diagnosis can be made. The aim of this study was to determine whether measurement of proliferative activity in Pap smears of postmenopausal patients that were difficult to interpret is a reliable test for differentiating between cervical atrophy and high-grade CIN. Methods. Pap smears obtained before and after estrogen treatment of 30 postmenopausal women with an atypical Pap smear were restained with the monoclonal antibody MIB1 to visualize proliferating cells. The proliferative activity index (PAI) was subsequently measured in order to explore the feasibility of a recently proposed PAI-based diagnostic decision tree to reduce the number of estrogen courses and follow-up Pap smears in postmenopausal women. Results. The PAI-based test to discriminate between cervical atrophy and high-grade CIN resulted in 100 and 96% correct diagnoses in women with high-grade CIN and cervical atrophy, respectively. Only 2 of the 30 women would have needed a repeated Pap smear after estrogen treatment for definite diagnosis if the PAI-based diagnostic decision had been used. Conclusions. Measurement of PAI in MIB1 restained Pap smears is a simple, reliable, safe, and probably also cost-effective method to obtain a substantial reduction of diagnostic estrogen courses and subsequent Pap smears in postmenopausal women with an atypical Pap smear.