Transependymal benign dorsally exophytic brain stem gliomas in childhood: diagnosis and treatment recommendations.

Sixteen children with dorsally exophytic transependymal benign brain stem gliomas were treated at the Hospital for Sick Children, Toronto, between 1949 and 1985. The diagnosis of these benign brain stem gliomas was based on neuroradiographic and operative observations. Five children were diagnosed in the pre-computed tomography (CT) era using ventriculography and pneumoencephalography, and 11 children were diagnosed using CT with and without contrast enhancement. Histological diagnosis was obtained in all 16 cases. In 1980, we first described this distinct group of benign brain stem gliomas, which accounted for 8% (total, 121 cases) of all brain stem gliomas diagnosed at our institution. However, with the use of high resolution CT in recent years, earlier and better definition of this particular type of brain stem tumor can be made. During the 10 years (1976 to 1985) in which CT has been used for preoperative evaluation in our institution, we have treated 49 patients with primary brain stem tumors. Eleven of these cases (22%) fell into the category of dorsally exophytic transependymal benign brain stem tumors. These tumors characteristically protrude into and largely fill the 4th ventricle, breaking through the overlying ependyma and frequently extending into the cisterna magna. On CT, they are isodense and enhance brightly with contrast agent. Clinically, these patients have a longer history of symptoms in comparison with patients with the more malignant, intrinsic types of brain stem tumor. All of our patients were treated by subtotal resection. Radiotherapy was utilized in 7 of the 16 patients.(ABSTRACT TRUNCATED AT 250 WORDS)