Six cases of malignant germ-cell tumors (grade 4)

The CT patterns of six malignant germ-cell tumors other than germinomas (one embryonal carcinoma, one choriocarcinoma, one yolk sac tumor, and three immature teratomas) were compared with those of 12 germinomas (ten suprasellar, one pineal, and one basal ganglia). The effects of irradiation and the changes in the concentration of serum α-fetoprotein (AFP) and human chorionic gonadotropin (HCG) were compared by means of serial studies. 1. Pre-contrast CT Four of the six (67%) malignant germ-cell tumors showed isodense masses with irregular margins that contained calcified dots and small necrotic cavities. All 12 germinomas showed round, high-density masses with smooth margins without necrotic cavities. The suprasellar germinomas showed no calcification on CT. 2. Post-contrast CT Both malignant germ-cell tumors and germinomas showed a strong enhancement after contrast administration. 3. Change in size after irradiation Malignant germ-cell tumors did not show a decrease in size after radiotherapy (20 - 40 Gy), although the necrotic cavities enlarged in three out of four tumors. Germinomas were highly radiosensitive and showed a remarkable change in size on follow-up CT after irradiation. 4. Serum AFP and HCG The concentrations of serum AFP and/or HCG before therapy were abnormally high in five malignant germ-cell tumors. In three out of four patients, the concentration of serum AFP was normalized, but in one patient the concentration of AFP increased even after irradiation. (author)