 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.
