馬尾領域に発生し感覚障害のみを症状とした類上皮腫の1例

A Case of Small Epidermoid Cyst in Cauda Equina with Manifest Regional Hypesthesia

　症例は22歳の女性で主訴は左腎部から左大腿後面内側部にかけての感覚鈍麻。神経学的診察で左側第3,4,5仙髄領域に限局した境界明瞭な感覚鈍麻と左側の肛門反射の消失が認められた。ミエログラフィーおよびMRI検査にて第4腰椎椎体後方に小さな占拠性病変が認められた。馬尾腫瘍が疑われ症状発現より約四カ月後に腫瘍摘出術が施行され，4本の馬尾神経を絞拘する腫瘍が認められ病理学的に類上皮腫と診断された。馬尾領域に発生し腫瘍が小さかったにもかかわらず選択的に4本の馬尾が障害され特異な臨床症状を呈したと考えられる。X線CTミエログラフィーおよびMRIが診断に有用であった。

This report concerns the 22-year-old female who has been suffering the paresthesia in the left buttock and thigh for three months. Neurological examina-tion revealed nothing other than hypesthesia and hypalgesia which distributed in the third, fourth and fifth segments of left sacral region with the loss of anal reflex. Pain had not been noticed until when she came to our clinic. Myelography and MRI showed small irregular round mass occupying a third of the spinal canal behind the body of fourth lumbar spine. In the axial view of MRI, the mass was enhanced by the gadolinium (Gd) except for the small portion of its center. She underwent the surgical treatment which revealed the tumor entangling four nerves of cauda equina in its center as imaged in MRI. The tumor was epidermoid cyst which presumably caused the chemical meningitis and involved those nerves. That resulted in the sensory disturbance in the left sacral region, although the tumor was not large enough to compress the nerves.