[Basal cell carcinoma of the perianal region: a case report and literature review].

The literature reports an annual incidence of 5,900 cases of anal cancer in the developed countries. These involve three different anatomic zones: carcinoma of the anal canal, perianal carcinoma (formerly known as carcinoma of the anal margin, located at a distance of less than 5cm from the anal margin), and carcinoma of the perianal skin (at a distance greater than 5cm from the anal margin). Basal cell carcinoma of the perianal region is an uncommon tumor (0.27% of all diagnosed basal cell carcinomas) that in the majority of cases is treated by resection with disease-free margins. It must be differentiated from the basaloid and epidermoid variants of carcinoma, given that it has good outcome and its spread potential is practically null.