Edema of the cortical gray matter of the human cerebrum.

Five cases of brain tumor are reported in which an extracellular edema of the cerebral cortex was recognized in the form of lakes of eosinophilic, PAS positive material, presumably serum proteins, permeating among the neuronal and glial cells and processes. In three, the astrocytes and their processes were stained in replicate paraffin sections by a gold sublimate technique. The astrocytic changes were variable. Most often, the astrocytes changed from protoplasmic to fibrillary, with long deeply stained processes, the cells sometimes becoming large and distorted. Many became enlarged and smudgy, with short stubby processes. Only a few showed the fragmentation and disintegration of processes. Only a few showed the fragmentation and disintegration of processes which are regularly observed in edematous white matter. The neuronal processes remained essentially normal. In comparison with edema of white matter, edema of the cortex is rare, involves only small portions of tissue, and differs in its effects on astrocytes. The edema in both cortex and white matter is extracellular. We have not been able to recognize a specific intracellular form of edema, grossly or with light microscopic techniques.