Atypical lesions of the anal mucosa in homosexual men.

Recent studies suggest that there is an increased incidence of squamous cell carcinoma of the anus in male homosexuals, but a precursor lesion has not been identified. We retrospectively analyzed in a blind fashion all anal tissue removed surgically during 1984. Twelve (6.7%) of the 180 specimens from men contained lesions with foci of epithelial atypia. Only one (0.85%) of 118 specimens from women harbored similar atypia. Of seven additional file cases exhibiting atypical anal mucosa, six were from men. Of 14 men with atypical anal lesions whose sexual orientation was known, 11 (79%) were homosexuals. In the 20 cases found to have atypical mucosal lesions, three patterns of atypia were identified, with more than one often occurring in the same specimen. Anal intraepithelial neoplasia (dysplasia) was identified in seven cases (35%) and occurred primarily at the anorectal junction and in anal ducts. Atypical condyloma was found in three cases (15%). A third lesion histologically indistinguishable from Bowen's disease or bowenoid papulosis was found in 12 cases (60%). In ten of these the lesion was adjacent to a condyloma. Although the natural history of these lesions of the anal mucosa is presently unknown, it may resemble that of similar lesions in other anatomic locations.