Clinical presentation and natural course of anogenital warts.

The natural history of human papillomavirus (HPV) genital tract lesions is complex, partly because infection can appear in several forms and often follows a fluctuating course. The primary mode of transmission of genital strains of HPV is through sexual contact. Most clinically apparent genital warts are caused by HPV type 6 or 11. The main manifestations of anogenital warts are cauliflower-like condylomata acuminata that usually involve moist surfaces; keratotic and smooth papular warts, usually on dry surfaces; and subclinical "flat" warts, which can be found on any mucosal or cutaneous surface. Latent infections that can be detected only by the presence of HPV DNA, with neither macroscopic nor histologic abnormality, are probably the most common form of anogenital HPV infection, regardless of HPV type. Most untreated genital tract lesions eventually resolve spontaneously, but it is likely that latent or subclinical infection persists indefinitely. The natural history of anogenital HPV infection is likely influenced by the cell-mediated immune system.