Clinical pathology of primitive gliomas in the cerebrum.

To clarify the biological features of primitive gliomas in the cerebrum and clearly distinguish them from malignant or anaplastic gliomas and glioblastomas, we studied eight cases clinically and pathologically. Our evaluations included immunohistochemical and electron microscopic observations. We divided the patients into two groups, children and young adults. Most tumours appeared as ring-like, enhanced masses on computed tomography and avascular or ring-like, vascular masses on angiography. Macroscopically, the tumours were well demarcated and contained cysts. Occassionally we found tumour dissemination. Microscopically, the tumours were composed of small, round cells without remarkable structural features. Ependymal, astroglial, and oligodendroglial differentiation was evident, in varying proportions; tumours in which the differentiated areas constituted more than half of the mass were classified as poorly differentiated gliomas. By these criteria, this series comprised four undifferentiated and four poorly differentiated gliomas. Cell anaplasia and polymorphism were rare in both undifferentiated and differentiated areas of the tumours. Immunohistochemical and electron microscopic examinations also revealed glial differentiation. These primitive gliomas appear to be biologically similar, but not identical, to cerebellar medulloblastomas. In this series, five patients died because of recurrence or dissemination. Whole brain and spinal irradiation should be considered after total or subtotal surgical removal.