[Significance of immunohistochemistry in neuro-oncology. I. Demonstration of glial fibrillary acid protein (GFAP) in extracranial metastases from primary brain tumors].

8 cases were studied to determine whether immunohistochemical investigation with anti-GFAP could contribute to confirming a primary brain tumor origin for an extracranial metastasis. The materials studied consisted of 3 glioblastomas, 3 anaplastic astrocytomas, and 2 medulloblastomas, along with their extracranial metastases. GFAP could be immunohistochemically demonstrated in all 6 primary glial tumors as well as in the metastases of the 3 astrocytomas and of 2 glioblastomas. The medulloblastomas and their metastases were immunohistochemically GFAP-negative. GFAP is thus a marker for extracranial metastases of astrocytomas and glioblastomas. A negative result however does not exclude the possibility that a metastasis is of glial origin as shown by the GFAP-negative metastasis of the one glioblastoma.