Frequency of occult high-grade squamous intraepithelial neoplasia and invasive cancer within anal condylomata in men who have sex with men.

Human papillomavirus causes anal condylomata, high-grade anal intraepithelial neoplasia, and anal squamous cell cancer. We found high-grade intraepithelial neoplasia or squamous cell cancer in 75 (47%) of 159 HIV-seropositive men who have sex with men (MSM) and in 42 (26%) of 160 HIV-seronegative MSM with anal condylomata meriting surgery (P<.001, determined by use of the chi(2) test).