Gliofibroma. A peculiar neoplasia of collagen forming glia-like cells.

A tumor of highly unusual composition was found in the lower medulla oblongata of a 3 year, 9 months old girl. Light microscopy of the lesion showed an intimate intermingling of astroglial processes with collagen fibers, both projecting congruent to the pattern of preexisting fiber tracts. Electronmicroscopy disclosed a mosaic formed by the intimate apposition of collagen bundles, of glial processes filled with glial fibrils, and of scattered myelinated fibers, all abutting upon each other, often without intervening basement membranes. This well differentiated mass within the medulla adjoined a dedifferentiated endophytic extension of the tumor into the fourth ventricle which had seeded into the cerebellar cortex and the cauda equina. The dedifferentiated portion of the neoplasm also displayed intimate apposition of collagenous and glial elements. The tumor was tentatively identified as a gliofibroma or a desmo-plastic glioma.