[Delayed radiation necrosis of the brain simulating a brain tumor--report of two cases (author's transl)].

Two cases of delayed radiation necrosis of the brain were reported. Case 1 was a 50-year-old man who had right hemiparesis and disorientation 26 months after Linac irradiation (5,000 rad), preceded by the operation for right maxillar carcinoma. A left carotid angiogram demonstrated a left temporal mass lesion, extending the frontal lobe. Case 2 was a 41-year-old man who had previously the operation for right intraorbital plasmocytoma, followed by two times Co irradiation (6,400 rad, and 5,000 rad). He had the signs and symptoms of intracranial hypertension 36 months after last irradiation. A left carotid angiogram demonstrated a left temporal mass lesion. Both cases were treated by administration of steroid hormone, which alleviated the signs and symptoms, followed by the temporal lobectomy. Microscopic examinations showed necrosis of the brain tissues associated with hyaline degeneration of blood vessel walls and perivascular cell infiltration. The signs and symptoms of intracranial hypertension subsided postoperatively. The other thirteen cases as same as ours were collected from literature, which showed the signs and symptoms simulating a brain tumor (like a metastic brain tumor) after the irradiation to extracranial malignant tumors, and the diagnosis of radiation necrosis were made by the operation or autopsy. A follow-up for a long time is necessary, because the pathological changes in the brain may be progressive and extending in some cases, although the decompressive operations for mass lesion are excellent in result.