慢性経過により腫瘤化した腰椎黄色靱帯内血腫の1例

Organized Hematoma in the Ligamentum Flavum. Case Report

　腰椎黄色靱帯内血腫が慢性経過を経て器質化し腫瘤状となった1例を経験した．症例は55歳の男性で，約1年間の硬膜外ブロックによる治療の既往があった．MRI上L3-L4高位の硬膜管背側にT1等輝度，T2高輝度の輝度変化を示す腫瘤性病変を認め，後方内視鏡手術で腫瘤の摘出を行った．この腫瘤は病理組織学的には赤血球とフィブリンの析出を認めることから血腫と考えられ，壊死組織の周囲を肉芽組織・硝子組織が被っている所見により，血腫が慢性経過をたどることで器質化し腫瘤様となったものと推察された．そのうえ，黄色靱帯と腫瘤の組織学的連続性を認めたことから黄色靱帯内に発生したものと考えられた．血腫の原因としては，頻回の硬膜外ブロックによる影響が考えられた．

　We report a case of the organized hematoma of the ligamentum flavum.　The patient was a 55-year-old man who came to our clinic because of intermittent claudication and bilateral leg pain.　He had been treated conservatively, mainly by means of epidural injections, for one year.　MRI revealed a dorsal tumor-like mass at the L3-L4 level of the spinal canal characterized by iso intensity on T1 weighted-images (WI) and a signal change and high intensity on T2WI images.　The tumor-like mass was removed by microendoscopic surgery, and there was an immediate improvement in his symptoms.　Histological examination revealed continuity between the mass and the ligamentum flavum.　The epidural injections may have caused a hematoma to develop in the ligamentum flavum, which may have become organized and formed a tumor-like mass over time.