The growing teratoma syndrome. A case of primary mediastinal nonseminomatous germ cell tumor treated with chemotherapy and radiotherapy.

A 21-year-old man presenting with a mediastinal mass was diagnosed as having primary mediastinal mixed nonseminomatous GCT by incisional biopsy and elevated serum concentrations of AFP and beta-HCG. After four courses of PVB chemotherapy followed by 4,000 rads of radiotherapy, the AFP level declined markedly, but the mediastinal mass further enlarged and underwent cystic change. Pathologic examination of the resected tumor only showed immature teratoma. The serum AFP level returned to normal and remained so three months after the operation. This experience suggests that in patients with nonseminomatous GCT treated with combination chemotherapy, measurements of tumor volume alone do not provide information regarding the tumor's response. Early recognition of the "growing teratoma syndrome" will allow for surgical salvage.