経過観察中に壁外性発育，直腸穿通をきたした直腸平滑筋腫に対する腹腔鏡補助下切除：1例報告

Laparoscopic resection for rectal leiomyoma with extramural growth and penetrating to the rectum during follow up : Report of a case

◆要旨：患者は79歳の女性で，2010年6月に悪性リンパ腫の治療歴があった．その際に施行した腹部CTで直腸右側に腫瘍性病変を指摘されていた．GISTや子宮筋腫が疑われていたが，悪性リンパ腫の治療が優先されたため，無治療で経過観察されていた．2016年の腹部CTで同病変は増大し内部に含気を有していた．下部消化管内視鏡では，直腸RS付近に腫瘍との交通が疑われる開口部を認め，同部より排膿を認めた．GISTも否定できず腹腔鏡補助下に切除を行った．病理所見では紡錘形細胞が錯走して増生し，免疫染色結果はαSMA（＋），desmin（＋），S-100（-），c-kit（-），CD34（-）であり，直腸平滑筋腫と診断した．GISTの概念が確立して以降，消化管の平滑筋腫の報告は稀となっている．今回，悪性リンパ腫治療後の経過観察中に壁外性発育，直腸穿通をきたした直腸平滑筋腫を腹腔鏡補助下に切除しえたので文献的考察を加えて報告する．

　A 79-year-old woman with a history of therapy for malignant lymphoma in June 2010 was found to have a tumorous lesion in the pelvic cavity on the right side of the rectum on an abdominal computed tomography （CT） examination performed at that time. On the abdominal CT examination performed in 2016, the lesion was larger and showed internal aeration that suggested a connection to the rectum. On colonoscopy, there was an opening at the upper rectum, and purulent discharge was observed from it. Since tumorous lesions such as GIST were suspected, laparoscopic tumor resection was performed. On pathological examination, spindle-shaped tumor cells in an interlaced bundle pattern were seen. Immunohistochemical findings were α SMA （＋）, desmin （＋）, c-kit （-）, CD 34 （-）, and S-100 （-）. The final pathological diagnosis was leiomyoma of the rectum. Since the concept of GIST has been established, leiomyoma of the gastrointestinal tract has become rare. In this report, a case of rectal leiomyoma with extramural growth and penetrating to the rectum that was resected by laparoscopic surgery during follow-up after treatment for malignant lymphoma was presented.