Cytokeratin Expression in Tumors of Neuroectodermal Origin

Abstract

Tumors of neuroectodermal origin include all those arising from the primitive medullary epithelium. In the CNS, these cells are neuroglia (astrocytes, oligodendrocytes, and ependymal cells) and the nerve cells. The corresponding tumors are gliomas, medulloblastomas, neuroblastomas, and ganglioneuromas. In this group, the primitive neuroectodermal tumors (PNETs) are regarded as an entity of closely related members sharing highly significant neuroectodermal and cytoskeletal similarities (Gould et al. 1990) and distinguishable from the classic CNS tumors. For discussion of cytokeratins in gliomas and meningiomas see Chaps. 4, 8, and 10. Interestingly, Gould et al. (1990) noted cytokeratin immunoreactivity, largely of the simple-epithelial type, in isolated cells or small cell aggregates in 3 out of 22 PNETs. They interpreted these findings in line with other cytokeratin observations in nonepithelial tumors (for review see Franke et al. 1989). In the intermediate filament study of Sime et al. (1989), which included 54 PNETs, mostly medulloblastomas, one case of a supra-tentorial PNET exhibited cytokeratin reactivity as revealed with the PKK1 antibody. Coffin et al. (1990) reported on 53 cytokeratin-negative cases of medulloblastomas. Furthermore, one congenital PNET case (Hachitanda et al. 1990) with epithelial and glial differentiation was found to be cytokeratin-positive. The list of intracranial tumors is incomplete without considering the intracranial germinomas which have a minority of cytokeratin-positive tumor cells (Gottschalk et al. 1987; Nakagawa et al. 1988), similar to their gonadal counterparts.