Karyotyping and DNA flow cytometry of mature residual teratoma after intensive chemotherapy of disseminated nonseminomatous germ cell tumor of the testis: a report of two cases.

Karyotyping and DNA flow cytometry was performed on mature residual teratoma cells following intensive chemotherapy of disseminated nonseminomatous germ cell tumor of the testis to study its biology. We report herein a successful method for short-term tissue culture and karyotyping of retroperitoneal residual mature teratoma in two cases. In vitro morphology confirmed that the cultured cells were nonembryonal carcinoma cells. Both mature residual teratomas were highly aneuploid and possessed the i(12p) marker characteristic of testicular germ cell tumors. A clone in the retroperitoneal residual lesion of one of the patients showed a DNA-index different from the primary tumor and might represent a clone unmasked by chemotherapy. In view of these data, which are in agreement with recent reports on secondary non-germ cell malignancies arising in mature residual teratoma, aggressive surgery of mature residual lesions seems justified.