Prognostic features of teratomas with malignant transformation: a clinicopathological study of 21 cases

PURPOSE: Teratomas with malignant transformation comprise up to 6% of metastatic teratomas. The prognosis of patients with these tumors can vary considerably. We delineate factors that may be related to prognosis in a cohort of men with teratoma with malignant transformation. MATERIALS AND METHODS: We analyzed pathological features, treatment, response, recurrence, time to recurrence, subsequent followup and survival for 21 patients (median age 28 years) diagnosed with teratoma with malignant transformation during a 7-year period at our institution. RESULTS: Malignant nongerm cell elements were present in the primary tumor in 11 cases (52%). Of 18 patients with testicular primaries 17 (94%) presented with metastatic disease. Despite aggressive treatment with surgery and chemotherapy 17 of 21 cases (81%) recurred (median time 6 months). Overall, 5 patients (24%) died of disease (median survival 23 months), 5 (24%) are alive with metastases (median followup 41 months) and 11 (52%) have no evidence of disease (median followup 50 months). Progression/recurrence was substantially greater for 2 of 2 cases with a mediastinal origin, 3 of 4 with rhabdomyosarcomatous differentiation and 5 of 6 with neural differentiation compared with the remainder of the cohort (p < 0.05). CONCLUSIONS: Teratomas with malignant transformation are usually metastatic at presentation, have a high recurrence rate and are more aggressive than teratomas without malignant transformation. Prognosis is especially poor for mediastinal teratomas with malignant transformation and for those with neural or rhabdomyosarcomatous differentiation. Complete surgical resection of residual or recurrent disease appears to offer the best chance for prolonged survival.