[A case of yolk sac tumor of the anterior mediastinum].

A 26-year-old male was clinically diagnosed as having a anterior mediastinal yolk sac tumor because of the elevation of the serum AFP (26,765 ng/ml) and a large mass lesion (13 x 12 x 8 cm) in the anterior mediastinum and right thoracic cavity. After three courses of chemotherapy with CDDP and VP-16, the mediastinal mass reduced in size significantly but the serum AFP level did not reach within normal range. We suspected that the tumor took a resistance to drugs, accordingly the operation was performed. The tumor was completely removed and there were small viable foci of the tumor in part of the tumor. The histological examination revealed the findings of yolk sac tumor. After the operation, the serum AFP level decreased within normal range. He is alive without evidence of recurrence during 18 months after operation. It was noticed that the serum AFP is a useful indicator for determining the chance of operation after chemotherapy.