Intracranial Ependymoma

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UNTIL recently, little has been added to our knowledge of the ependymal group of gliomas as first described by Bailey1 in 1924. In the following year, Bailey2 presented the results of the study of 5 cases designated as ependymoblastoma and 7 as ependymoma. These results originated the conception that the tumors were malignant primarily because of their predilection for the fourth ventricle, a site presenting surgical difficulties in the complete removal of such growths. Although the impression has persisted that ependymoblastomas grow-more rapidly and are more malignant lesions than ependymomas, analysis of the first series reported by Bailey and Cushing2 failed to corroborate this assumption. Also, Bailey later recognized the fact that, insofar as prognosis was concerned,3 the difference between these tumors was minimal. His conclusion was emphasized further by Davidoff3 and later by Mabon et al4 and Penfield.5

Kernohan and Fletcher-Kernohan6 in 1937 subdivided the ependymomas into the following subtypes: (1) epithelial, (2) cellular, (3) myxopapillary and (4) papillomas of the choroid plexus. This classification also included the neuroepithelioma of Bailey and Cushing in the general group of ependymomas. Although an attempt was made to correlate the prognosis with these individual subdivisions, the results were unsatisfactory. More recently (1949), Mabon, Svien, Kernohan and Craig4 reviewed 57 cases of ependymoma in which the patients were operated upon, and graded the neoplasms according to pleomorphism of nuclei and cytoplasm, hyperchromatism, mitotic figures and preservation of architecture.

They found a close correlation between the degrees of dedifferentiation of these gliomas and the. . .



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