Delayed onset of clear cell adenocarcinoma of the vagina in DES-exposed progeny.

Clear cell adenocarcinoma of the vagina occurred in a diethylstilbestrol (DES)-exposed patient in the fourth year of continuous observation for adenosis. Diagnosis was suspected by digital and colposcopic examination and confirmed by target biopsy. Cytology was negative. The development of malignancy in a patient who has been known to have adenosis has been previously described but is very rare. The necessity for careful regular follow-up using cytology, digital palpation, and colposcopy at 6-month intervals is emphasized.