Intraventricular neurocytoma with prominent myelin figures

A case is reported of inraventricular neurocytoma that had characteristic l ight microscopic findings of neurocytoma with prominent intracytoplasmic co ncentric lamellar structures mimicking myelin sheaths. On routine H&E-stain ed sections, this tumor showed intracytoplasmic vesicular bleb-like structu res having eosinophilic cores that were consistent with ultrastructural con centric lamellar structures. Immunohistochemically, this tumor was immunore active for synaptophysin and neurofilament, but negative for antibody to gl ial fibriallary acidic protein. Electron microscopic findings fulfilled the criteria for neurocytoma, with the presence of neurosecretory granules and neurotubules. These findings may suggest dual differentiation of this tumo r into neurocytes and oligodendrocytes.