Background: The designation of a teratoma with malignant transformation (TMT) refers to the occurrence of somatic non-germ cell malignancies within a teratoma. While TMT is a rare but well recognised phenomenon in adult germ cell tumors (GCT), data on TMT in pediatric GCTs are lacking.
Patients and methods: Between 1982 and 2003, 641 patients with extracranial nontesticular pure teratoma (256 coccygeal, 246 ovarian, 139 other sites) were reported to the MAKEI protocols 83/86/89/96 by various, mainly German centres. Patients with teratoma and somatic malignancy were identified by database queries. Patients with malignant germ cell tumor components were excluded from this analysis. The clinical files were reviewed and re-evaluated centrally. Information was actualized by requisition to the participating hospitals.
Results: We identified nine patients (all female, age 0-39 years) meeting the histological criteria of TMT. Two patients had coccygeal teratomas and seven ovarian tumors. Carcinoma was the dominating malignancy (five of nine cases). Tumors with glial differentiation and embryonal tumors occurred in two cases each. Resection was performed in seven patients (including both coccygeal tumors) and adjuvant chemotherapy was administered in one of them. Two patients relapsed after resection, but both were cured with chemotherapy. Two patients suffered from advanced tumors and both were treated with primary chemotherapy. One patient was cured from the malignant component (astrocytoma), but the teratomatous components persisted. The other patient died as a result of progression of her malignant medulloepithelioma.
Conclusions: Malignant transformation of pure teratomas constitutes a very rare entity in children and adolescents that is most commonly observed in postpubertal girls with ovarian teratoma. Compared to adult patients, similar malignant entities can be observed in association with teratoma. However, in our series, no sarcoma was diagnosed. In localised tumors, complete resection appears to be adequate, whereas chemotherapy should be considered in patients with R1- or R2-resection. Cisplatinum-based chemotherapy was effective as two of four relapsed patients survived tumor free. However, the ideal regimen has not yet been established and the known sensitivity of the histologic components to cytostatic drugs has to be considered in the choice of treatment. Further molecular biologic studies are necessary to understand the origin of these tumors.