[Adenocarcinoma of anal canal. Report of a case and review of the literature].

Carcinomas of the anal channel includes only 2 to 6 per cent of all colorectal tumors. They are squamous cell carcinomas, cloacogenic carcinoma and unusually, adenocarcinomas. A 41 year old man in which an adenocarcinoma of the anal channel developed within a chronic perianal fistula, is presented. A review of the literature about adenocarcinoma or the anus is made, and then the incidence, probable etiologies, biologic behavior, clinical features, diagnosis, differential diagnosis and treatment are enunciated. This rare tumor is associated with chronic inflammatory disease of the anal channel because of its etiology (fistula-in-ano, condyloma acuminata), because of cellular changes that are perpetuated by local immunologic blockade. We conclude that any chronic inflammatory disease must be treated early and adequately to avoid metaplastic and frank neoplastic changes. A deep and early biopsy of any benign lesion must be made if it does not respond to treatment, and a histopathologic exam of any tissue resected in orificial surgery must be performed. We suggest to use the classification of histological typing used by the W.H.O. and the staging of cancer by the U.I.C.C. and A.J.C.C. (1987).