 Primary syphilis is typically acquired by direct sexual contact with the infectious lesions of another person . Approximately 3 to 90 days after the initial exposure ( average 21 days ) a skin lesion , called a chancre , appears at the point of contact . This is classically ( 40 % of the time ) a single , firm , painless , non @-@ itchy skin ulceration with a clean base and sharp borders between 0 @.@ 3 and 3 @.@ 0 cm in size . The lesion may take on almost any form . In the classic form , it evolves from a macule to a papule and finally to an erosion or ulcer . Occasionally , multiple lesions may be present ( ~ 40 % ) , with multiple lesions more common when coinfected with HIV . Lesions may be painful or tender ( 30 % ) , and they may occur outside of the genitals ( 2 – 7 % ) . The most common location in women is the cervix ( 44 % ) , the penis in heterosexual men ( 99 % ) , and anally and rectally relatively commonly in men who have sex with men ( 34 % ) . Lymph node enlargement frequently ( 80 % ) occurs around the area of infection , occurring seven to 10 days after chancre formation . The lesion may persist for three to six weeks without treatment . 
