Which type of malignancy is found in anorectal fistula

Although rare, the incidence of anal squamous cell carcinoma (SCC) is rising, with a direct association with HPV infection, AIN and immunosuppression. Thus, high-risk groups are those infected with HPV (especially subtypes 16, 18, 31 or 33) .Advanced tumours may cause faecal incontinence by invasion of the sphincters and, in women, anterior extension may result in anovaginal fistulation Ref: Bailey & Love&;s Sho Practice of Surgery,E25,Page-1269