Clinical impact of atypical squamous cells of undetermined significance -: A cytohistologic comparison

OBJECTIVE: To assess the percentage of squamous intraepithelial lesions (SILs) in the atypical squamous cells of undetermined significance (ASCUS) cytologic diagnosis. STUDY DESIGN: From January 1994 to December 1995, 421 cervical Pap smears with a diagnosis of ASCUS were followed with cervical biopsies within three months. The ASCUS cytologic diagnosis was correlated with the histologic findings and stratified according to age group, previous abnormal history and cell type of ASCUS (squamoid vs. metaplastic). RESULTS: Histologic diagnosis showed that of ASCUS diagnoses, 13% were normal, 34% were reactive, 4.8% were atypical, 43% were low grade SIL, 4% were high grade SIL, 1% were carcinoma in situ, and none were invasive lesions. The patients in the youngest group, up to 25 years, demonstrated the highest percentage of SIL. Patients with a previous abnormal gynecologic history showed a higher percentage of SIL than those without an abnormal history. SILs were observed in 52.5% of squamoid ASCUS and 36.5% of metaplastic ASCUS. CONCLUSION: Forty-eight percent of females having an ASCUS diagnosis on Pap smears had SPL and thus a preneoplastic lesion. The highest percentage of SIL was found in females 25 years and younger. Our findings suggest that an ASCUS diagnosis warrants ongoing follow-up.