A Case of Iatrogenic Benign Cyst Infection Arising at the Anastomosis after Functional End-to-End Anastomosis for Cecal Cancer

Implantation cysts are iatrogenic cystic lesions that develop at anastomotic sites, most commonly following double-stapling technique anastomoses.

A 77-year-old woman underwent laparoscopic ileocecal resection with functional end-to-end anastomosis for cecal cancer. Contrast-enhanced CT performed 6 months postoperatively revealed a 25-mm cystic lesion contiguous with the anastomotic stapler line, protruding extramurally from the bowel wall. The lesion was diagnosed as an iatrogenic benign cyst at the anastomotic site, and careful observation was adopted. Six years and six months after surgery, the cyst became infected. Elective laparoscopic local resection was performed, resulting in complete resolution.

Histopathological examination demonstrated features resembling an enteric duplication cyst, suggesting that an isolated intestinal structure became cystic due to mucin production. To our knowledge, no cases reported since 1990 have described cyst formation with subsequent infection following functional end-to-end anastomosis. This case does not meet the classical definition of an implantation cyst. With the increasing use of linear staplers for intracorporeal anastomoses, similar lesions may be encountered. Accumulation of such cases may support recognition of this entity as an "anastomotic duplication cyst".