SYP and neoplasm: In addition, immunohistochemical staining revealed marked immunoreactivity for S100-protein, neuronal specific enolase, CAM5.2 and cytokeratin 8/18, while the tumor was focally immunoreactive for synaptophysin; however, the tumor was found to be negative for glial fibrillary acidic protein (GFAP) and epithelial membrane antigen.