Anal neoplasia

Anal squamous intraepithelial lesions are increasingly prevalent in both HIV(+) and HIV(-) men and women. Progression to high-grade SIL may be an intermediate stage toward malignant transformation to squamous cell carcinoma of the anus. The past 20 to 30 years have seen an alarming increase in anal cancer rates, particular in high-risk populations such as homosexual men where the incidence reaches 35/100,000. Infection by certain strains of HPV is causally associated with both SIL and anal cancer and it is becoming clearer that anal HSIL is the precursor to invasive anal cancer. There is now evidence that Bowen's disease and anal HSIL are pathologically the same and this should be reflected in the treatment strategies for both entities. Our preferred treatment strategy includes high-resolution anoscopy directed biopsy for high-grade dysplasia or invasive cancer and follow-up Papanicolaou (Pap) smears. In the presence of high-grade dysplasia, intraoperative biopsy with high-resolution anoscopic mapping and lesion destruction is performed with resultant complete eradication of dysplasia in immunocompetent patients. There are numerous pathologic similarities between anal HSIL/anal cancer and cervical HSIL/cervical cancer. Considering the impact of cervical cytology screening on the incidence of cervical cancer, strong consideration should be given to screening for anal cancer using anal cytology in high-risk populations.