Transition of benign vaginal adenosis to clear cell carcinoma

The transition from benign adenosis to clear cell carcinoma of the vagina has not been established beyond doubt. The history of a patient regularly followed in a diethystilbestrol (DES) clinic shows initial benign adenosis with normal cytology and subsequent development of abnormal cytology and clear cell adenocarcinoma. The authors suspect transition from benign epithelium to malignancy; however, detailed serial histologic study failed to show clear transition. Frequent and thorough examination of DES patients is needed if malignant change is to be diagnosed early.