Growing teratoma syndrome.

Growing teratoma syndrome is the term applied to enlarging retroperitoneal or other metastatic masses containing mature teratoma during chemotherapy for nonseminomatous germ cell tumors. Four cases of the growing teratoma syndrome are presented, the metastatic masses being in the retroperitoneal in all the cases. All these patients had enlarging retroperitoneal masses in the presence of normal serum biomarkers following chemotherapy for nonseminomatous tumors. Surgical excision was carried out in all four patients, with disease free survivals ranging from 6 to 24 months after surgery.