The malignant potential of postchemotherapy residual mature teratoma for disseminated nonseminomatous testicular tumors.

Flow cytometric nuclear DNA ploidy analysis was used to study 7 paraffin-embedded tissue blocks from 3 patients with postchemotherapy residual mature teratomas. All specimens contained abnormal DNA and were classified as DNA aneuploid. These findings indicate that despite the benign appearance of postchemotherapy mature teratomas, these lesions are susceptible to resume malignant behavior. Therefore, complete surgical removal is recommended.