A case of malignant teratoma developing from the septum pellucidum 7 years after removal of a mature teratoma in the pineal region.

A report is presented on a case of teratoma with a malignant component arising from the septum pellucidum 7 years after total surgical removal of a mature teratoma in the pineal region. The patient was successfully treated with radiotherapy and total surgical resection of the second tumor. The case is characterized by the development of a second malignant tumor and by the long interval from complete resection of the primary tumor to the occurrence of the second tumor. Our case is not considered to be a recurrence of the mature teratoma of the pineal region but to be a multiple tumor of germ-cell tumor having multicentricity and a different temporal variety.