直腸癌術後局所再発との鑑別を要し腹腔鏡下手術を施行したimplantation cystの1例

Laparoscopic resection for implantation cyst at anastomotic site after rectal cancer surgery which was difficult to differentiate from local recurrence : A case report

◆要旨：患者は77歳，男性．2年前に直腸癌にて腹腔鏡下高位前方切除術，double stapling techniqueによる吻合を施行した．術後2年の腹部CT検査で吻合部腹側に多発する囊胞性病変を認め，緩徐に増大傾向を示すため，局所再発を疑い当院紹介となった．PET-CT検査では有意なFDG集積がみられたため，直腸癌の局所再発と診断し腹腔鏡下手術を施行した．病理組織学的検査所見では悪性所見は認めず，最終的にimplantation cystと診断された．本症は消化管吻合の際に生じる稀な合併症であり，直腸癌術後の局所再発との鑑別に苦慮することが多い．今回，局所再発を疑い腹腔鏡下手術を施行したimplantation cystの1例を経験したので，文献的考察を交えて報告する．

　A 77-year-old man had previously undergone high anterior resection for rectal cancer with the double stapling technique. Two years after this surgery, abdominal computed tomography （CT） and magnetic resonance imaging （MRI） showed multiple cystic lesions at the ventral side of previous anastomotic site. Since fluoro-deoxy-glucose positron emission tomography （FDG-PET） showed some accumulation of FDG at the site of the lesions, we diagnosed them as local recurrence and performed laparoscopic low anterior resection. Histopathological examination showed no malignant findings and the cystic lesions were diagnosed as implantation cysts. Implantation cyst, which is not widely recognized, is one of the rare complications occurring after intestinal anastomosis. The pathogenesis of implantation cysts may be explained by the production of mucus from the mucosal epithelium of the colon or rectum caught under the submucosa, forming a cyst after anastomosis. It is very important to differentiate implantation cyst from other submucosal lesions such as local recurrence of cancer, but it is not easy. The case which showed FDG accumulation by FDG-PET is extremely rare and no previous cases which performed laparoscopic surgery have been reported. We report this rare case with a review of the literature.