Subependymoma of the lateral ventricle.

The case of a girl with a large cystic subependymoma of the lateral ventricle is reported. The tumor, which did not cause hydrocephalus, was attached to the wall of the frontal horn and grew out of the ventricular system extending into the anterior cranial fossa and the orbital cavity. Despite some typical features exhibited by the lesion, its true nature was not recognized during the operation. The importance of the identification of this rare benign tumor is emphasized because a radical removal may be accomplished in most cases with a very good prognosis.