特異的遺伝子転座を認めず胞巣状構造を呈した横紋筋肉腫の1例

Rhabdomyosarcoma Exhibiting Alveolar Features in the Absence of a Specific Gene Translocation. Case Report

　胞巣状構造を呈するが特異的遺伝子転座を認めない横紋筋肉腫1例を経験したので報告する．症例は1歳2カ月の女児で，針細胞診で横紋筋肉腫と診断し，広範切除を行った．術後組織病理学所見では，胎児型の部分と胞巣状構造が混じったパターンであった．典型的胞巣型と異なり，線維性間質に乏しく，大量の横紋筋芽細胞が混在するのが特徴であった．胞巣型に特異的なt（2；13）またはt（1；13）の転座を認めなかった．術後6年9カ月の現在，多発性転移を認め，再発と軽快を繰り返し，現在化学療法中である．

　We report a case of rhabdomyosarcoma that exhibited atypical alveolar featurs in the absence of a specific chromosomal translocation. The patient was a 14-month-old girl with a soft tissue mass on the lateral aspect of her right thigh. The diagnosis based on the fine-needle aspiration cytology findings was rhabdomyosarcoma, and wide resection was performed. The postoperative histopathologic examination revealed embryonal portions alternating with an alveolar pattern. The tumor differed from the typical alveolar type because of the paucity of fibrous septa and the presence of a large number of rhabdomyoblasts. Neither the t (2；13) or t (1；13) alveolar-type-specific translocation was identified. During the six years nine months since surgery multiple-metastases have occurred, and the primary tumor has repeatedly recurred.