Mixed intracranial sarcomas: rare forms and a new association with previous radiation therapy.

The first two instances of mixed sarcoma-glioblastoma with a history of therapeutic irradiation to the head are reported, both occurring within one year of radiation therapy (for pituitary adenoma and residual meningioma). Two novel variants of mixed sarcomas of brain with extreme tumor metaplasia (fibromyxoosteochondrosarcoma and fibrochondroosteosarcoma-glioblastoma multiforme) are documented, and some of the problems concerning the origin of brain tumors with mixed population are discussed.