The main symptom of stage I syphilis is a hard chancre, which usually occurs 2-4 weeks after unclean sexual intercourse. In women, the hard chancre mostly occurs on the labia or cervix, and in men, it occurs on the foreskin, coronal sulcus, tether or glans of the penis. In gay men, it can occur in the anus or rectum. In addition, it can occur on the lips, throat or other parts of the body. The typical hard chancre is a painless, round rash, slightly above the skin surface, 1-2 cm in diameter, with clear boundaries, a broken surface, and a small amount of exudate on the erosion surface. It is a painless round rash, slightly above the skin surface, with a clear border and a small amount of exudate on the vesicular surface. A few days to a week after the appearance of the hard chancre, the adjacent lymph nodes may be palpably enlarged. The exudate from the hard chancre and the lymph node puncture fluid contain a large number of syphilis spirochetes. If left untreated, the chancre may resolve spontaneously within 3-8 weeks, leaving no trace or only a mild atrophic scar. The period during which the hard chancre is present is clinically known as stage 1 syphilis. The longer the hard chancre is present, the higher the rate of positive syphilis seropositivity in the patient. By 6-8 years after the appearance of the hard chancre, almost all patients are seropositive for syphilis. The picture shows a hard chancre that occurs in the glans of a man.