Primary syphilis
The average incubation period is 3-4 weeks. The typical lesion is hard chancre (Ulcus Durum), which begins with a small red papule or induration at the site of spirochete invasion, and then shows erosion, forming a superficial ulcer, which is hard, painless, round or oval, with clear boundaries, neat edges, dike-like uplift, dark red infiltration around it and characteristic chondroid hardness. Hard chancre is mostly single, and there are 2-3 cases. The above is a typical chancre. However, if it occurs in the original erosion, laceration or erosive herpes or balanitis, chancre will take the same form as the original damage, and this situation should be checked by Treponema pallidum. Hard chancre is infected by sexual intercourse, so the damage mostly occurs in vulva and sexual contact parts, and in men, it is mostly near glans penis, coronary sulcus and frenulum, prepuce or inner leaf of penis, root of penis, urethral orifice or urethra, and the latter is easy to be misdiagnosed. Hard chancre is often complicated with foreskin edema. Some patients may have lymphangitis on the back of penis, showing hard linear damage. Women's hard chancre is more common in labia majora, clitoris, urethral orifice, pubic mound, especially in the cervical region, and it is easy to be missed. Hard chancre outside pudenda is more common in lips, tongue, tonsils, fingers (medical staff can also infect hard chancre), breasts, eyelids and external ears. In recent years, anorectal chancre is not uncommon. This chancre is often accompanied by severe pain, difficulty in defecation and easy bleeding. Occurring in the rectum is easily misdiagnosed as rectal cancer. Hard chancre occurring outside the vagina is often atypical, so treponema pallidum examination and genetic diagnosis should be carried out. Hard chancre has the following characteristics: ① the damage is often single; ② Chondroid hardness; 3 no pain; ④ The damaged surface is clean.
A week after chancre appeared, the nearby lymph nodes were swollen, showing no pain, no redness and swelling on the skin surface, no adhesion with surrounding tissues and no ulceration. It is called painless transverse scrotum (painless lymphadenitis). If the chancre is not treated, it will heal itself after 3-4 weeks. After effective treatment, it can heal quickly, leaving superficial atrophic scars. After 2-3 weeks of chancre, syphilis serum reaction began to be positive. In addition to chancre, a few patients with primary syphilis can still have hard and tough edema in labia majora, foreskin or scrotum. Like an elephant skin, it is called edema and induration. If the patient is infected with chancre caused by Haemophilus Dukley or erosive ulcer caused by lymphogranuloma of venereal disease, it is called mixed chancre.
The diagnosis basis of primary syphilis: ① the history of unclean sexual intercourse with a incubation period of 3 weeks; ② Typical symptoms, such as simple painless chancre, mostly occur in external genitalia; ③ Laboratory examination: PCR detection of Treponema pallidum gene positive or dark field microscope detection of Treponema pallidum in chancre; Syphilis serum test was positive. One of these three tests is positive.
Differential diagnosis: The diseases that need to be differentiated from primary syphilis are
① Genital herpes: there is slight erythema at the onset, and small clustered blisters are formed after 1 or 2 days, which are itchy and painful, but not hard, and can disappear after 1-2 weeks, but it is easy to recur. Tissue culture was herpes simplex virus, and Tzank smear was positive. PCR was positive for herpes virus DNA.
② Pyoderma like chancre: The pathogen is Staphylococcus aureus or Streptococcus. The morphology of the lesion is similar to chancre, but there is no typical cartilage hardness, no dark red infiltration around it, no clean sexual history, and Treponema pallidum is negative. The nearby lymph nodes can be swollen, but the lesions will disappear after healing.
③ chancre: It is also one of sexually transmitted diseases, with a history of sexual contact, caused by Haemophilus. The incubation period is short (3-4 days), with acute onset, obvious inflammation, pain, soft skin, frequent skin lesions, purulent secretions on the surface, and negative serum tests for Haemophilus Duklei and syphilis.
④ Tuberculous ulcer: It is also common in penis and glans penis. The skin lesion is also a single superficial circular ulcer with scab on the surface and mild symptoms, so tuberculosis can be checked. Often accompanied by visceral tuberculosis.