抄録
症例は6歳の男児で,仙尾部の正常皮膚に覆われた軟部腫瘤例である.初診時,直腸肛門奇形や歩行障害,排便・排尿障害を認めず,髄膜瘤やhuman tailが疑われた. MRIでは,軟部腫瘤像に尾骨成分を認めず,脊椎骨との交通性も指摘されなかった.さらに3D-CTで二分脊椎症の合併を認めたが椎骨前面での腫瘤像等は認めず,術中所見でも腫瘤と脊椎骨とに交通性を認めなかったため,腫瘤摘出術のみを施行した.病理組織学的に成熱型奇形腫と診断され,最終的に奇形腫と二分脊椎症に伴ったpseudo-human tailと考えられた.Human tailにはtrueとpseudoがあり本症例のようなpseudo-human tailには二分脊椎症やtethered cord症候群を合併することが多く,術前診断においてCTやMRIでtailに続く索状物様像の有無や腰仙部の異常の有無を精査し,摘出手術にのぞむことが肝要である.
We report a clinical case which a soft mass (2.5×2.0×1.2 cm in size) covered with normal skin on the sacrococcygeal portion was seen in a 6-year-old boy. In addition, anorectal malformations, dysbasia, dyschezia, and dysuria were not seen at the initial examination, nor was any mass palpable in the rectum by means of digital examination with an index finger. MRI examination was performed in order to make a differential diagnosis of human tail (true or pseudo tail), meningocele, teratoma, epidermal cyst, lipomeningocele and so on. The soft mass had no coccyx in it or communication with cerebrospinal fluid (CSF). Moreover, 3D-CT examination showed the existence of spina bifida but still no mass could be seen in front of the spinal cord. Simple mastectomy was performed and the communication of a soft mass and the spinal cord were not confirmed in the operation. A diagnosis of mature teratoma about the resected mass was made based on histopathological findings. The final diagnosis of the mass was mature teratoma and pseudo-human tail with spina bifida. The pseudo-human tail without coccyx involves some complications of spina bifida, tethered cord syndrome and so on. It is important to perform further examination by means of MRI and 3D-CT at preoperation in the case of a soft mass being seen at the sacrococcygeal portion in order to rule out some anomalies or complications.
