All sections from the brain tumor contained an extremely cellular and pleomorphic tumor tissue with a herringbone pattern of spindle cells (Figure 1a) which were positive with vimentin immunostaining. Alternating with these areas were islands of fibrillar and gemistocytic astrocytes intensely positive for GFAP on immunostaining. Both GFAP positive and negative giant cells were seen (Figure 1b). Between the other tumor components there were a few clusters of small anaplastic tumor cells, which did not react with these markers (Figures 1c, 1d). Mitoses were numerous in all parts of the tumor, as were the MIB-1 and p53 stained nuclei, and several geographic necroses were found.
In the palpebral and oral metastases only the sarcomatous herringbone pattern was seen (Figures 2a and 2b), and GFAP could not be demonstated by immunohistochemistry in spite of the use of a highly sensitive tyramine amplification technique.