Sixty-four malignant hemispheric
tumors in children less than 15 years old were treated in the pediatric neurosurgical department of the Hôpital des Enfants Malades between 1970 and 1989. (1) These
tumors evolved rapidly in most cases. However the pre-operative evolution in 20% of the patients had a duration of more than 6 months, which favors the hypothesis that at least one-fifth of these
tumors result from malignant transformation of a benign lesion. This observation should prompt neurosurgeons to operate on all benign hemispheric
tumors as soon as they are diagnosed. (2) Five of the 64 patients had two successive malignant diseases. In four cases the other malignant disease was an
acute lymphoblastic leukemia. (3) Among the malignant hemispheric
tumors, the grade III and IV
astrocytomas had a dismal prognosis. As it is known from previous studies that grade I and II
astrocytomas have a good prognosis in children, it can be concluded that grading these
tumors is essential. By contrast, almost one out of two patients with malignant
ependymoma was alive 5 years
after treatment. This implies that the grading of
ependymomas is of modest prognostic values. (4) The harmful effect of
radiotherapy was evaluated by comparing the functional outcome of children operated for a benign hemispheric
tumor to that of children operated and irradiated for a malignant hemispheric
tumor.