[A clinicopathological study of nine cases of midbrain glioma]

The majority of brain stem gliomas tend to occur during childhood and arise in the pons. The prognosis of these typical pontine gliomas is almost invariably bad. In contrast, there exists a group of benign brain stem gliomas, mostly arising from the midbrain and are amenable to surgical resection. They are often low-grade astrocytomas and are associated with better prognosis. We summarized nine cases of intrinsic midbrain gliomas and their clinical behavior was analyzed by radioimagings and histopathological examination. They were classified from CT images according to Stroink et al. and from anatomic staging by Epstein. The result showed that 5 in 9 cases were so called, "focal midbrain gliomas". That is to say, the tumor arose from the tectal plate or the tegmentum of the mesencephalon and expanded dorsally, but did not invade the surrounding neural tissues. Three focal midbrain gliomas in childhood were well demarcated and surgically resectable. Histologically, tumors were astrocytomas and were associated with favorable prognosis. However, two focal midbrain gliomas in adulthood were anaplastic astrocytoma and the prognosis was poor, even though they appeared similar shown on radioimaging study. The overall survival rate of patients with midbrain glioma was longer than that of patients with glioma in the cerebral hemisphere. From these results, it was concluded that a specific group of intrinsic, focal midbrain gliomas can be classified into pediatric benign gliomas and adolescent malignant ones. A further number of cases should be studied to clarify this hypothesis.