Synchronous mucinous adenocarcinoma of the recto sigmoid revealed by and seeding an anal fistula. (A case report and review of the literature)

Highlights • The diagnosis of such conditions remains difficult when the colonic tumor is unknown and the chronic lesion of anal fistula seems to be a benign condition. • The management of these cases remain controversial. • The aim of this study highlights the importance of high suspicion with further investigation and the need of biopsy in all anal fistulas.