Cerebral "radiation necrosis": vascular and glial features.

Glial and vascular abnormalities in brain, simulating intracranial neoplasia, are described in a patient who received radiation to the pituitary region for treatment of an adenoma, 13 months before death. In addition to the expected changes of cerebral radionecrosis, four interesting features are cited: 1. Diffuse hyperplasia of capillaries in the cerebral cortex with marked endothelial hypertrophy; 2. abundant, large multipolar bizarre cells in the perivascular connective tissues; 3. focal astrocytic proliferation with many cells resembling either Alzheimer type I astrocytes or neoplastic cells, and 4. radiation changes in the non-irradiated brain.