メシル酸イマチニブ投与後に会陰操作を先行した腹腔鏡下ISRにて切除した直腸GISTの1例

Neoadjuvant therapy using imatinib mesylate followed by laparoscopic intersphincteric resection for low rectal gastrointestinal tumor : Report of a case

◆要旨：患者は60歳，女性．下部直腸に3cm大の粘膜下腫瘍を指摘され，当院を受診した．直腸GISTと診断し，腹会陰式直腸切断術，腟後壁合併切除を薦めたが，強い肛門温存希望があり，メシル酸イマチニブを導入した．2か月の投与で腫瘍最大径は30％縮小し，腹腔鏡補助下括約筋間直腸切除術を施行した．腫瘍は腟と近接しており，偽被膜損傷を避けるため，会陰操作を先行し腟後壁の合併切除を行った．腫瘍の口側まで全周性に剝離した後，腹腔鏡操作で頭側から剝離し，会陰より腫瘍を摘出した．腟および肛門管に極近接した本例では，メシル酸イマチニブの術前投与と会陰操作の先行がきわめて有用であった．

A 60-year-old woman with low rectal submucosal tumor, 3 cm in diameter, was referred to our hospital. The tumor was diagnosed as gastrointestinal stromal tumor（GIST）. Although abdominoperineal resection with combined resection of the posterior wall of the vagina was recommended for R0 resection, she strongly hoped preservation of the anal function. Pre-operatively, imatinib mesylate was administrated for 2 months and 30％ decrease of the maximum diameter of the tumor was obtained. Laparoscopic intersphincteric resection was performed. Because the tumor was extremely close to the posterior wall of the vagina, we performed trans-anal dissection first. To avoid exposure of the tumor, the posterior wall of the vagina was resected and the rectum was fully mobilized to the oral side of the tumor. Then, the rectum was easily mobilized by laparoscopic trans-abdominal approach and the tumor was extracted through the anus. Preoperative administration of imatinib mesylate and preceding trans-anal approach was fairly valuable to preserve the anal function.