摘出術前の放射線治療が有効であった富血管性孤立性線維腫の1例

Efficacy of Preoperative Radiation Therapy in Hyper-vascular Solitary Fibrous Tumor

Ⅰ．はじめに

　頭蓋内に発生するsolitary fibrous tumor（SFT）は，現在のところ明確な診断基準がなく，hemangiopericytoma（HPC）やfibrous meningiomaとの鑑別が困難である．なかでも血管成分に富んだSFTについては，過去に2例の報告がなされたのみであり^6,10)，その病理組織学的分類をはじめ，治療方法についても明確な見解は確立されていない．一般にSFTに対する治療は，外科的摘出術を主体として行われているが，ときに放射線治療も行われ，特に再発例や転移例，部分摘出例などに対する報告が散見される^1,2,9)．しかしながら，摘出術難渋例に対して放射線治療を行ったとする報告は渉猟し得た限り認められない．

　今回われわれは病理学的に富血管性のSFTと診断した症例に対し，初回手術時に出血コントロールに難渋して部分摘出に終わったが，その後に放射線治療を行うことで，腫瘍の大幅な縮少と栄養血管の消退が得られ，全摘出し得た症例を経験したので報告する．

　The hyper-vascular form of solitary fibrous tumors (SFTs) is rare and there have been few therapeutic evaluations of this entity. We encountered a hyper-vascular SFT and had difficulty removing it surgically. Following radiotherapy, both tumor size and feeder vessels were reduced and we could proceed with gross total removal.

　A 29-year-old woman was admitted with a 1-year history of decreasing visual acuity on the right side. Magnetic resonance imaging with gadolinium enhancement showed a homogenous enhancing mass (6×5×5cm) which expanded the superior and inferior tentorium cerebelli. The tumor was fed by the left posterior cerebral artery, bilateral middle meningeal arteries and the right occipital artery. The first operation employed an occipital transtentorial approach and a highly vascular tumor was found. Tumor resection was limited due to severe bleeding. Histologically, the tumor showed focal hypercellularity with spindle cells and numerous capillaries. Immunohistochemically, the tumor was diffusely positive for CD34 and a diagnosis of SFT, hyper-vascular subtype, was made.

　After the first operation, local irradiation of a total of 40Gy was performed. Both the tumor size and vascularity decreased dramatically. At the second operation, gross total removal was able to be performed. Radiotherapy appears effective in reducing the hyper-vascular subtype of SFT and would be one possible therapy to deal with these tumors, given their propensity of excessive bleeding during initial surgery.