大量出血で発症した右後頭葉放射線壊死の1例—病理組織学的検討

A Case of Radiation Necrosis in the Right Occipital Lobe Accompanied with Massive Hemorrhage:Histopathological Analysis

Ⅰ．はじめに

　放射線治療は，頭蓋内腫瘍や転移性脳腫瘍，脳血管奇形に対して行われる標準治療法の1つである．放射線治療後の遅発性合併症として，髄膜腫や海綿状血管腫などの放射線誘発腫瘍の発生や遅発性放射線壊死が知られている．放射線治療後の脳出血の原因は，一般に海綿状血管腫からの出血報告が多いと言われている³⁾．

　今回われわれは，放射線治療後18年経過して大量出血で発症した症候性遅発性放射線壊死を経験した．遅発性放射線壊死を伴う出血例は珍しく，病理学的検討を加え報告する．

Radiation necrosis with massive hemorrhage is a rare complication of radiotherapy. We report the case of a male patient who had undergone radiotherapy therapy 18 years earlier and presently underwent gamma knife radiosurgery for a metastatic brain tumor in his right occipital lobe. The patient showed aberrant behavior with left homonymous hemianopsia and a gradual deterioration of cognitive function after radiotherapy. A CT scan showed the presence of an intracerebral hematoma over the right occipital lobe with mass effect, and small spotty enhancements on the lesion when enhanced on gadolinium contrast-enhanced MRI. Intraoperative findings revealed necrosis of the occipital surface and a hematoma in the occipital lobe. Pathological findings showed damage to the walls of the sinusoidal capillaries and vitreous degeneration of the inner membrane with a spongiform hemangioma. After surgery, the cerebral edema resolved, and the patient's clinical symptoms improved. The cause of the radiation necrosis and bleeding in this patient was assumed to be due to the breakdown of the congested walls of the sinusoidal capillary vessels.