Squamous cell carcinoma of the anal canal

Squamous cell carcinoma of the anal canal is a rare epithelial intestinal neoplasm, arising from squamous epithelial cells in the anal canal, with variable macroscopic appearance, ranging from small, benign lesions (that mimick fissures, hemorrhoids or anorectal fistulae) to a large, exophytic or ulcerating tumor localized within the anal canal. Patients may be asymptomatic or present difficulty to defecate, anal bleeding, pain and/or discharge, and often have a history of chronic anal fistulae and abscesses, Crohn's disease, hemorrhoids, or, especially in younger patients, immunosuppression (such as HIV infection). Association with HPV infection is commonly reported.