Fig. 2

Pathology Slides. a Metastatic Intradural Tumor: The tumor is very cellular consisting of sheets of tumor cells (hematoxylin-eosin, original magnification X20). b Metastatic Intradural Tumor: The cells are haphazardly arranged and spindled with short, ovoid, irregular, hyperchromatic nuclei with scattered large atypical nuclei (hematoxylin-eosin, original magnification X200). c, d Metastatic Intradural Tumor: The cytoplasm is eosinophilic and moderate in amount with variable vacuolization. Occasional nuclear inclusions are seen. (hematoxylin-eosin, original magnification X400). e, f Metastatic Intradural Tumor: The tumor cells are diffusely positive for KIT (CD117) (e) and ANO-1 (DOG-1) (f) immunohistochemical stains (original magnification X400). g, h The original gastric biopsy shows a subepithelial tumor consisting of predominantly bland small epithelioid spindled cells with vacuolated cytoplasm and smudged chromatin. Rare large cells are noted, but not to the extent seen in the metastatic tumor (hematoxylin-eosin, original magnification X20 and X200, respectively)