初回手術9年後に肝転移を来した異型髄膜腫の1例

A Case of Atypical Meningioma with Liver Metastasis at 9 Years after Initial Surgery

Ⅰ．はじめに

　髄膜腫は，くも膜表層細胞より発生する脳実質外の腫瘍であり，全頭蓋内腫瘍の15〜18%程度と頻度は高い．髄膜腫の局所再発率は18%程度と低くないが，頭蓋外転移は極めて稀であり，その頻度は文献上0.15%程度と報告されている²⁾．その頻度の低さから，転移の機序について未だ定説はない．今回われわれは，初回手術9年後に肝転移を来したものの，予後良好に経過している異型髄膜腫の1例を経験したので，文献的考察を加えて報告する．

　Metastatic meningiomas are extremely rare, and generally have poor prognosis. We report a case of atypical meningioma with good clinical course despite metastasis 9 years after the initial surgery.

　CASE:A 58-year-old woman visited a nearby hospital with complaints of hemiplegia and aphasia. MRI showed a large left frontal meningioma;she was referred to our department where she underwent a tumor resection（Simpson Grade Ⅰ). Histopathological finding revealed fibrous meningioma in the prominent part of the tumor. Additionally, a small lesion with high Ki-67 labeling index was identified;therefore, the final diagnosis was atypical meningioma. Nine years postoperatively, a hepatic mass found incidentally and was resected by digestive surgery;a histological diagnosis of metastatic atypical meningioma was established. Thirteen years after the first operation, routine MRI showed enlargement of the local recurrent lesions in the tumor resection cavity. She underwent a reoperation（Simpson Grade Ⅰ）at our department, and subsequently, discharged without any neurological deficits. Findings were not suggestive of atypical meningioma.

　Studies report three good prognostic factors in patients with metastatic meningioma-histologically benign primary tumor, long interval between initial diagnosis and metastasis, and asymptomatic metastatic lesion.