The sexually transmitted disease that may produce a chancre is syphilis. A chancre is a painless swelling (lesion) on the skin, most probably around the genital area. Syphilis is a sexually transmitted disease (STD) caused by a bacterium. Although it can be treated with antibiotics, if the treatment doesn't start soon enough, syphilis can become a very serious health condition. Its progression involves 4 stages. Syphilis can cause serious damage to the nervous system with symptoms that range from severe headaches to changed behaviour.