BACKGROUND: The growing teratoma syndrome refers to the phenomenon whereby germ cell tumors enlarge after chemotherapy despite complete eradication of malignant cells and normalization of serum tumor markers. This clinical scenario must be differentiated from that in which germ cell tumors maintain their malignant characteristics with elevated levels of serum tumor markers. METHODS: Hospital record review was conducted of 2 cases. RESULTS: Two male patients are presented, 1 with a metastatic germ cell tumor of both the retroperitoneum and mediastinum (with elevated alpha-fetoprotein level) and 1 with a primary germ cell tumor of the mediastinum (with elevated alpha-fetoprotein and beta-human chorionic gonadotropin levels). After completion of chemotherapy and normalization of tumor markers, both patients presented with pulmonary symptoms attributable to their massively enlarging mediastinal teratomas. The clinical and roentgenographic features of patients with thoracic manifestations of the growing teratoma syndrome, as well as its management, are reviewed. CONCLUSIONS: After chemotherapy in patients with primary or metastatic mediastinal germ cell tumors whose tumor markers normalize, a growing mass in the mediastinum may represent the growing teratoma syndrome.
