The main manifestation of stage I syphilis is a hard chancre. Generally, 2-4 weeks after infection with the syphilis spirochete, red papules and superficial erosions begin to appear on the external genitalia and other areas, and ulcers are formed a few days later with little pain. The typical presentation is a single or multiple slightly elevated round or oval ulcers, 1-2 cm in diameter, with relatively clear boundaries and a hard cartilage-like base. The surface of the ulcer is clean and there is a thin plasma exudate after squeezing. The chancre often occurs on the external genitalia, such as the prepuce, tether or head of the penis in males; the labia, clitoris and cervix in females; and outside the genitalia, the breasts, perianal area, anal canal and rectum, and lips of the mouth can be involved. One to two weeks after the onset of the disease, unilateral or bilateral inguinal lymph nodes can appear enlarged. The enlarged lymph nodes are usually painless, hard in texture, and usually do not suppurate or break down, and do not adhere to the surrounding tissues, which is syphilitic cross-craft.