To clarify the histogenesis and differentiation potential of
central neurocytoma, a pathological investigation of seven
tumors from three patients was conducted using immunohistochemistry and ultrastructural analysis in addition to systematic in vitro studies. Six
tumors were studied immunohistochemically and five were examined ultrastructurally. All cases that were immunostained were positive for
synaptophysin in nuclear-free neuropil islands. In five
tumors, a few
tumor cells, in addition to reactive astrocytes, were positive for
glial fibrillary acidic protein (GFAP).
Vimentin staining was also positive in a few
tumor cells of five specimens. Neurofilament staining was always negative. All cases for which ultrastructure was examined showed various synaptic abnormalities. Cultured cells were subdivided into three distinct
tumor cell types: neuronal cells which stained for
neurofilament proteins with neurosecretory granules; small flat undifferentiated cells with a high nuclear-cytoplasmic ratio and scant cytoplasmic organelles; and small round or multipolar astrocytic cells with 10-nm intermediate filaments which stained for GFAP. Our tissue culture studies disclosed that cultured
neurocytoma cells form a cellular mosaic similar to subependymal plate layers that are composed of mitotically active cells, neurons and glia.