骨髄転移を来したIDH変異・1p/19q共欠失乏突起膠腫の1例

A Case of Bone Marrow Metastasis of Oligodendroglioma with IDH Mutation and 1p/19q Codeletion

Ⅰ．はじめに

　2016年のWHO脳腫瘍分類第4版改訂版では，従来の形式学的分類のみでなく，分子情報を合わせた診断名が用いられることとなった．とりわけ神経膠腫については，分子遺伝学的知見を重視するという方向性がHaarlemコンセンサスガイドライン（2014年）¹⁶⁾において打ち出された．乏突起膠細胞系腫瘍はその考え方が最も色濃く反映された腫瘍型の1つとなり，乏突起膠細胞系腫瘍の診断にはIDH変異の有無と1p/19q共欠失の有無についての検討が必要となった．

　乏突起膠腫は成人に発生するびまん性，浸潤性に進展する腫瘍で，近傍の軟膜直下にもしばしば浸潤が及ぶとされるが，頭蓋外転移の報告は極めて少ない．今回われわれは，術後約半年で多発骨髄転移を来した症例を経験したので，文献的考察を加えて報告する．

　A 71-year-old woman was transferred to our hospital, complaining of a seizure for the first time. A tumor was detected in the right frontal lobe, and a craniotomy was performed with a partial tumor resection. The pathological diagnosis was oligodendroglioma with IDH mutation and 1p/19q codeletion, and irradiation therapy was performed. Six months later, the patient's lactate dehydrogenase（LDH）level elevated remarkably, and the fluoro-deoxyglucose-positron emission tomography/computed tomography showed abnormal uptake in multiple bone marrow locations. Bone marrow aspiration was performed, and the pathological diagnosis was oligodendroglioma metastasis. The patient was given two cycles of chemotherapy with temozolomide（TMZ), and her LDH level reduced to normal. After a few months, the LDH level elevated again, so we gave her two more cycles of TMZ;however, her LDH level did not change. Thereafter, the patient was hospitalized because of paraplegia, which started a few days prior, and right lower jaw swelling. Her CT and magnetic resonance imaging showed metastasis to the thoracic vertebrae and right mandibular bone. Irradiation therapy was performed to these locations, and the patient was given chemotherapy using nimustine（ACNU), procarbazine, and vincristine（PAV). Her LDH levels reduced temporarily, but elevated again. The patient deteriorated slowly and died 20 months after she presented with a seizure. Oligodendroglioma with extracranial metastasis is extremely rare, and this case report is the 68th report. The chemotherapy approach with TMZ or PAV/PCV may be effective against oligodendroglioma metastasis to the bone marrow.