大脳鎌に発生したintracranial extraskeletal mesenchymal chondrosarcoma

Intracranial Extraskeletal Mesenchymal Chondrosarcoma Arising from Falx: A Case Report and Literature Review

Ⅰ．緒言

　Mesenchymal chondrosarcomaは，1959年にLightensteinとBernsteinにより，低分化な小型円形細胞と軟骨組織からなる骨の悪性腫瘍として初めて報告された¹²⁾．発生母地としては骨由来のものが70％以上と最も多く，次いで軟部組織が20％，以下縦隔，眼窩などからの発生が報告されている^5,10,21)．頭蓋内に発生することは非常に稀で，原発性脳腫瘍全体の0.16％以下であり⁹⁾，そのほとんどは骨から発生する．頭蓋内で骨以外から発生したとする報告はさらに稀である．今回，われわれは大脳鎌から発生したintracranial extraskeletal mesenchymal chondrosaromaの1例を経験したので，術前の画像診断，治療法について文献的考察を加えて報告する．

　Intracranial extraskeletal mesenchymal chondrosarcoma is a very rare tumor that affects young adults. We report a 31-year-old woman with a huge intracranial extraskeletal mesenchymal chondrosarcoma. She presented with a history of right homonymous hemianopsia for 6 months. Computed tomography scans demonstrated a heterogeneously enhanced mass,in the right occipital region,which was lobulated and contained areas of calcification. Magnetic resonance imaging demonstrated a large mass (67mm) of heterogenous intensity that showed enhancement and was attached to the falx cerebri. The patient underwent right occipital craniotomy and subtotal removal of the tumor. At operation,the tumor was found to arise in the falx cerebri and the cranial vault was not involved. Pathologic examination revealed a mesenchymal chondrosarcoma. She underwent conventional radiotherapy after surgery and remained free of progression at the 20-month follow up. We review previously reported cases of extraskeletal intracranial mesenchymal chondrosarcoma and discuss imaging diagnosis,treatment strategies,and outcome.