腹腔鏡下に切除した大腸平滑筋肉腫の1例

A case of leiomyosarcoma of colon treated by laparoscopic surgery

◆要旨：患者は60歳代，男性．主訴は黒色便．大腸内視鏡検査にてS状結腸に7mmのⅠspポリープを認めた（Group3, adenoma）．10か月後の大腸内視鏡検査でポリープは3cmに増大し，sm浸潤が強く疑われた．生検では間葉系悪性腫瘍と診断した．術前画像検査で転移はなく，腹腔鏡下S状結腸切除術（D3）を施行した．組織学的には，異型の強い大型核や多核の紡錘形腫瘍細胞が束状に交錯しながら増殖し，免疫染色でh-caldesmon（＋），vimentin（＋＋＋）と一部で平滑筋への分化が示唆され，平滑筋肉腫と診断された．腹腔鏡下手術手技が確立している施設において，5cm以下の大腸平滑筋肉腫に対する腹腔鏡下手術は，有用な治療法であると考えられた．

　A 60-year-old male was admitted to our department with the chief complaint of melena. Preoperative diagnosis was mesenchymal malignant tumor of the sigmoid colon. There were no distant metastasis and laparoscopic sigmoidectomy （D3） was performed safely. Postoperative histopathological diagnosis was leiomyosarcoma. The tumor was 4× 3.5× 3 cm in size, and h-caldesmon（focal＋），vimentin（＋＋＋），desmin（-），α-SMA（-），c-kit（-），CD34（-），S-100（-） in immunnohistochemical examination . There were no lymphnode metastasis. There were no signs of recurrence for about 2 years after surgery. The safety of laparoscopic surgery for leiomyosarcoma of the colon is unclear, however, it may be useful option to resect small size tumors （<5cm） radically. In Japan,laparoscopic colectomy for leiomyosarcoma of the colon was performed in only 5 cases in 2008, 14 cases in 2009. We report ,for the first time, a case of successful laparoscopic resection of leiomyosarcoma of the sigmoid colon.