Single males have a six-fold higher incidence than married males, and this appears due to the high prevalence of HPV infection associated with anal intercourse. There is a recent significant rise in the incidence of anal squamous carcinoma associated with the rise in HPV infection. An increased incidence has also been noted in renal transplant patients with immunosuppression. The tumors present as mass lesions which are exophytic with a smooth surface which may be ulcerated in larger lesions. They are present above and below the Dentate Line.
Cut surface is firm and white.
The microscopic appearance is variable as several variants exist. Most commonly their appearance is similar to non-keratinizing cervical squamous carcinoma. Regardless of histologic variant, squamous carcinomas of the anus show similar behavior with direct extension into the sphincter, vagina, perianal tissue and prostate. Lymphangitic spread through the perirectal and groin nodes are both seen. Primary treatment is surgical with local resection limited to Stage 1 and small Stage 2 lesions.