Histopathologic correlation of atypical parakeratosis diagnosed on cervicovaginal cytology

To retrospectively examine the histopathologic findings in women with the isolated finding of atypical parakeratosis (PK) on a Pap test.

The cytology files (1999-2001) were searched for cervicovaginal Pap tests interpreted as atypical PK. Cases were included for study only if there was a subsequent cervicovaginal tissue sample within 1 year of the cytologic interpretation and there was no diagnosis of squamous intraepithelial lesion (SIL) within the previous five years.

Of 355 patients with atypical PK, 109 (aged 14-69 years, mean 31.5) met the inclusion criteria of the study. The interval between the cytologic interpretation and cervicovaginal tissue examination ranged from 0.5 to 12 months (mean, 2.5). Sixty-one patients underwent both endocervical curettage (ECC) and cervical biopsy (CBx), 20 patients underwent ECC only, 19 patients underwent CBx only, and the remainder underwent other procedures. Histopathologic findings on the tissue samples included: no significant pathologic change but no squamous epithelium present for evaluation (n = 10, 9.2%), benign changes other than hyperkeratosis and/or PK (n = 50, 45.9%), hyperkeratosis and/or PK (n = 8, 7.3%), low grade SIL (n = 33, 30.3%), high grade SIL (n = 6, 5.5%) and invasive squamous cell carcinoma (n = 2, 1.8%).

The isolated finding of atypical PK on a Pap test correlated with the presence of an underlying SIL or invasive carcinoma in approximately 40% of patients. Of these, 80% had low grade SIL. The cytologic finding of atypical PK warrants further investigation in order to exclude SILs and/or carcinoma. We suggest that atypical PK be routinely included in the category of atypical squamous cells of undetermined significance.