Adenocarcinoma of the anal canal with an exceptional immunohistochemistry in a patient with serrated polyposis syndrome: a diagnostic challenge.

Anal adenocarcinomas account for approximately 10% of all anorectal tumours. We present the case of an adenocarcinoma of the proximal anal canal with exceptional immunohistochemistry as an incidental finding after haemorrhoidectomy, in a patient with endoscopically controlled serrated polyposis syndrome. Histopathological analysis of the specimen was a challenge in terms of differential diagnosis, which often determines the choice of therapeutic approach.