A congenital tumor arising from an embryologic rest in the region of the pituitary body and the sella turcica is rarely encountered even in a large neurosurgical clinic, but the occurrence is sufficiently frequent to warrant consideration of such a tumor in the differential diagnosis of the cause of disturbance of vision in a child or a young adult. Particularly is this true if the patient's vision cannot be improved with corrective lenses or if there is edema of the optic disks as observed on funduscopic examination. The diagnosis of a tumor in the chiasmal region usually is not difficult if the condition is considered as a possibility.
Cases of intracranial tumor arising from a residual cell rest of the primitive hypophysial duct were reported as early as the latter part of the nineteenth century. The early reports were based on both operative material and material obtained at necropsy. In