The tumor was composed of two intertwined cellular types as demonstrated on H&E (Figure 5, 200x). Numerous neoplastic ganglion cells with large nuclei, prominent nucleoli, and large cytoplasms were seen as well as multinucleated forms. A higher magnification of the gangliocytic component revealed globose NFTs within the cytoplasm of ballooning ganglion cells (Figure 6, 400x). The second component was formed by fibrillary astrocytes in a fibrillary background (Figure 7, 400x). Minimal pleomorphism was seen within the astrocytic component. Multifocal calcifications and perivascular chronic inflammatory infiltrates were also evident.
Many NFTs were seen with Bielschowsky (Figure 8) and Gallyas silver stains (Figures 9 and 10).
Immunostaining for GFAP (Figure 11) was strongly positive within the fibrillary background surrounding neoplastic ganglion cells and focally in the enlarged cytoplasm of astrocytes. PHF (Figures 12 and 13) immunostained numerous neurons with and without well formed NFTs. Synaptophysin (Figure 14) immunostained around and focally within the cytoplasm of ganglion cells suggesting that they are neoplastic. Note that fibrillary astrocytes lack staining. Immunostaining for ß-amyloid was negative.