放射線照射後20年を経て発生した脳幹部神経膠腫の1例

Brain Stem Glioma Induced by Radiotherapy:Report of a case

Ι．はじめに

　頭部放射線照射により発生する放射線誘発脳腫瘍の多くは頭皮疾患に対する低線量照射後に発症することが多い．しかし，近年原発性脳腫瘍に対する高線量照射後に発生してくる脳腫瘍の報告がみられるようになってきた．

　組織型としては髄膜腫，肉腫が多く，神経膠腫は比較的少い．しかもテント上に発生する場合が殆んどで，脳幹部に限局した放射線誘発脳腫瘍の報告は極めて稀である．

A case of brain stem glioma following radiotherapy for brain tumor is presented.

A 44-year-old female was admitted with chief com-plaints of gait disturbance and disturbed consciousness. She had received radiation thrapy with 60Gy follow-ing resection of a right temporal astrocytoma 20 years before, but until admission this time follow up CT scan had shown no regrowth. On admission CT scan and MRI showed an enhanced mass (2×2.5cm) in the mid-brain. Tumor biopsy was performed using the subtem-poral approach. The histological diagnosis showed a fibrillary astrocytoma grade Ⅲ.

The patient received postoperative synchronized che-motherapy but expired 8 months after admission. The growth of glioma appeared in the previous radiation field after a long latent period.

This case should be considered not as a case of the regrowth of a tumor but as a case of a radiation in-duced tumor. Although 77 cases of gliomas following radiation for intracranial tumor have been reported, this case of radiation-induced brain stem glioma is extreme-ly rare.