Immature neural elements in immature teratomas. An immunohistochemical and ultrastructural study

Immature neural tissue pathobiology in teratomas may have important implications for clinical prognosis, nervous system embryology, and neurological oncology. However, immunohistochemical and ultrastructural examinations of these neoplasms have been scarce. The authors examined immunohistochemically the immature neural elements in nine immature teratomas. Using modified peroxidase-antiperoxidase (PAP) immunoperoxidase (IP) techniques, they evaluated the immunoreactivity to glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), neurofilament (NF), chromogranin (CG), and vimentin (VM). All nine teratomas were immunoreactive for both GFAP and NSE, one was reactive for NF, and five (56%) were immunoreactive for vimentin. All cases were nonreactive for chromogranin. In addition, ultrastructural examination (electron microscopic [EM]) was performed on eight of these tumors. By EM examination, both astrocytes and oligodendroglia were identified in varying stages of development. Astrocytes often displayed abundant intermediate filaments. However, primitive undifferentiated cells were also found. Neuronal differentiation included long cell processes with tubules and filaments, vesicles, rare dense-core granules, and synapses. Ependymal differentiation (cilia, microvilli, prominent junctions) was observed in two cases. Pigmented retinal epithelium was seen in one tumor. No ambiguous (hybrid) cells were identified. Cellular interactions usually resembled the relationships found in normal adult brain tissue.