[Immunohistochemical studies of hemangioblastoma with glial fibrillary acidic protein].

Sixteen cases of CNS hemangioblastoma were examined for glial fibrillary acidic protein (GFAP) using the immunoperoxidase method. In 13 cases GFAP-positive cells were found in the tumor. In all positive cases reactive gliosis in the form of trapped reactive astrocytes and their cytoplasmic processes penetrated the margin of the tumor. In 4 of the positive cases GFAP-positive cells were present deep in the tumor. Aggregates of GFAP-positive cells and fibrils were especially prominent in a recurrent case. Because hemangioblastomas grow without capsule into the cerebellar tissue, it is considered that reactive astrocytes and their fibrils are easily included and trapped within the tumor. In two cases GFAP-positive plump stromal cells, which were definitely different from the reactive astrocytes, were seen. They were neighbored with the dense gliotic foci or on and around the microcyst wall. This may be interpreted as that the stromal cells have a capacity to incorporate the extracellular GFAP derived from the intratumoral gliotic foci or cysts.