[Implantation metastasis of colorectal adenocarcinoma in an anal fistula].

In our case report, we describe a rare form of metastatic colorectal carcinoma, in which tumor cells spread intraluminally and metastasis occurs with implantation mechanism far from the primary tumor. A 43-year-old male patient developed perianal abscess. After surgical intervention a fistula-in-ano appeared at the site of the abscess.