Purpose: High-resolution anoscopy is colposcopy of the anus after applying 3 percent acetic acid. High-resolution anoscopy with biopsy was used as the standard for detecting high-grade anal neoplasia and was compared to detection of high-grade anal neoplasia by anal cytology, human papillomavirus testing, or the combination.
Methods: A total of 125 men who have sex with men (MSM) were enrolled from a group of MSM identified by random digit dialing: HIV-negative = 85, HIV-positive = 35, and unknown status = 5. A specimen was taken for anal cytology and human papillomavirus testing, followed by high-resolution anoscopy with biopsy of any lesions.
Results: Ninety-one percent of HIV-positive and 57 percent of HIV-negative MSM had anal human papillomavirus infection. In HIV-positive men the sensitivity of abnormal cytology to detect high-grade anal neoplasia was 87 percent, and in HIV-negative MSM it was 55 percent. Among HIV-negative men, 9 of 20 cases of high-grade anal neoplasia would have been missed because cytology was negative, but the addition of human papillomavirus positivity increased sensitivity for the combination to 90 percent.
Conclusions: Sensitivity and specificity of anal cytology and human papillomavirus testing are different in HIV-positive and HIV-negative MSM for detecting high-grade anal neoplasia when patients have high-resolution anoscopy-guided biopsy of lesions. The optimum use of human papillomavirus testing has yet to be defined. High-resolution anoscopy is an effective tool for diagnosing high-grade anal neoplasia.