Neurocytoma is a type of nervous system benign tumor which is primarily derived from nervous tissue. This is in contrast to the gliomas (such as oligodendroglioma), which are derived from glial cells, and not from nervous tissue. Neurocytoma is a type of nervous system benign tumor which is primarily derived from nervous tissue. This is in contrast to the gliomas (such as oligodendroglioma), which are derived from glial cells, and not from nervous tissue.