External genital and perianal warts are caused by the infection of human papillomavirus or HPV. HPV infection is a sexually transmitted disease (STD). External genital warts look like small flesh-colored, pink, or red growths on or around the external skin of sex organs or perianal area. The warts may look similar to the small parts of a cauliflower or they may be very tiny and difficult to see. They often appear in clusters of three or four, and may grow and spread rapidly. They usually are not painful, although they may cause mild pain, bleeding, and itching.