High prevalence of anal squamous intraepithelial lesions and squamous-cell carcinoma in men who have sex with men as seen in a surgical practice.

Introduction: Anal high-grade squamous intraepithelial lesions are probable invasive anal squamous-cell cancer precursors, and although unproved, treatment of high-grade squamous intraepithelial lesions may prevent progression to anal squamous-cell cancer. Men who have sex with men are often treated for benign anorectal disorders without consideration given to the possibility of concurrent high-grade squamous intraepithelial lesions or anal squamous-cell cancer. We determined the prevalence of anal high-grade squamous intraepithelial lesions and anal squamous-cell cancer in an urban surgical practice of men who have sex with men referred for treatment of anal condyloma and other benign noncondylomatous anal disorders.

Methods: One hundred thirty-one HIV-positive and 69 HIV-negative men who have sex with men referred for surgical treatment of presumed benign anorectal disease were evaluated by anal cytology, high-resolution anoscopy, and biopsy. Anal cytology and histology were reported with a modified Bethesda classification.

Results: One hundred fifty-seven patients (79 percent) were referred for condyloma, 4 (2 percent) for anal squamous intraepithelial lesions (anal high-grade squamous intraepithelial lesions) diagnosed by primary care providers, and 39 (19 percent) for other benign anorectal disorders. One hundred forty-three patients (93 percent) had abnormal anal cytology, with 107 (54 percent) having high-grade squamous intraepithelial lesions on cytology. Biopsy results revealed 120 patients (60.0 percent) with high-grade squamous intraepithelial lesions and 5 patients (3 percent) with invasive squamous-cell carcinoma. Four of five men with anal squamous-cell cancer were HIV positive. Fourteen men (36 percent) who have sex with men referred for noncondylomatous benign anal disorders had high-grade squamous intraepithelial lesions, and three (8 percent) had anal squamous-cell cancer. High-grade squamous intraepithelial lesions and anal squamous-cell cancer were seen most often at the squamocolumnar junction.

Conclusions: Men who have sex with men referred for treatment of either condyloma or noncondylomatous benign anorectal disease had a high prevalence of anal high-grade squamous intraepithelial lesions and anal squamous-cell cancer. All men who have sex with men referred for treatment of benign anorectal disease should have high-resolution anoscopy and aggressive biopsy of all abnormal areas. Treatment of external lesions alone could miss high-grade squamous intraepithelial lesions or anal squamous-cell cancer.