Perianal Bowen's disease associated with anorectal warts: a case report.

The occurrence of anogenital warts has increased both in clinic and in private practice. Both sexes and all races are affected, with the highest prevalence in patients aged 15 to 40 years. The etiologic agent, the human papillomavirus (HPV), has been classified by DNA hybridization techniques into at least 42 types, of which types 16 and 18 are considered to carry a high risk for cancer. A patient who had been seen intermittently over a period of 26 years with perianal and anal warts that responded to treatment finally developed two granulomatous nodules morphologically different from the previous lesions. A biopsy confirmed that the nodules were typical of Bowen's disease, a precancerous lesion, and they were surgically excised. Thus, anogenital warts that fail to respond to conventional therapy or change in appearance warrant a biopsy and, where the technique is available, DNA typing to identify the viral pathogen.