Colosigmoid adenocarcinoma anastomotic recurrence seeding into a transsphincteric fistula-in-ano: a clinical report and literature review.

We describe the case of a left colon adenocarcinoma anastomotic recurrence that metastasized to a benign transsphincteric fistula-in-ano, presumably through the implantation of viable malignant cells shed from the secondary tumor, and discuss the implications of these findings in colorectal cancer surgery.