Sequential CT observations of irradiated intracranial germinomas.

Computed tomography (CT) has improved the accuracy of preoperative diagnosis of intracranial tumors. CT findings of germinoma are a mass of isodensity or of slightly increased density with significant, homogeneous enhancement after intravenous contrast injection. These findings are characteristic but not pathognomonic, and differential diagnosis from other solid tumors is not easy. Cerebrospinal fluid cytology and response to irradiation aid in this differential diagnosis. The nine cases of germinoma reported showed rapid response to irradiation even at small doses (600 rad), and complete disappearance of the mass on CT at 1,600--3,300 rad. Other radiosensitive masses to be differentiated in the pineal region are pinealocytoma or pinealoblastoma.