Cytologic evidence of extensive keratotic reaction in women exposed to diethylstilbestrol in utero.

Squamous mucous membranes and squamous metaplastic epithelium sometimes undergo hypermaturation with the production of a keratin layer. Anucleated keratotic squamous plaques in smears are generally recognized as cytologic evidence of this altered maturation. This keratotic reaction was quantified in cytologic smears from 191 women exposed in utero to diethylstilbestrol (DES). Keratotic reaction was observed in the vaginal smear in 40% of the cases, in the cervical smear in 26% and in the endocervical smear in 19%; overall, a keratotic reaction was observed in at least one specimen from 48% of the women. These frequencies are higher than those reported in other studies. The observed frequency was age related. The significance of the hyperkeratosis, including its possible relationship to a lower dysplasia rate among DES-exposed women, is unclear. No conclusions can be drawn until more is known about behavioral factors in DES-exposed women.