Lymphogranuloma venereum, also known as the fourth sexually transmitted disease, is one of the classic sexually transmitted diseases, whose pathogen is Chlamydia trachomatis and is transmitted mainly through sexual contact. Its main clinical manifestations are transient blistering damage in the genital area, local lymph node enlargement, elephantiasis and rectal stricture in the late stages of untreated disease, which is highly destructive to the tissues. This disease is now relatively rare in China. Etiology The etiologic agent of venereal lymphogranuloma is serotype L1, L2, and L3 of the 15 serotypes of Chlamydia trachomatis. Compared with the other serotypes, the L type has a stronger invasive power. It is transmitted mainly through sexual contact, and occasionally by contamination or experimental accidental transmission. The disease was more common in China before and at the beginning of liberation, and after 1991, disseminated cases were reported in some areas. By 2001, hundreds of cases were reported each year, but the reported cases were not confirmed by serological testing or culture. Clinical manifestations 1. Incubation period The incubation period is 5 to 21 days with a history of unclean sexual intercourse. 2.Early symptoms The initial sores are mostly small blisters, papules, erosions and ulcers of 5-6 mm around the penile body, glans, coronal sulcus and foreskin in men and vaginal vestibule, labia minora, vaginal opening and urethra in women, often single, sometimes several, with no obvious symptoms, which do not heal in a few days and do not leave a scar after healing. 3.Mid-term symptoms 1-4 weeks after the appearance of the initial sore, male inguinal lymph nodes swollen (fourth venereal disease cross-craft), pain, pressure, adhesions, fusion, visible “groove sign” (inguinal ligament separates the enlarged lymph nodes up and down, the skin is groove-like). After a few weeks, the lymph nodes soften, rupture, and discharge yellow slurry or bloody pus, forming multiple fistulas that look like “squirt pots” and do not heal for months, leaving scarring after healing. In women, the initial sore mostly occurs in the lower part of the vagina and flows back to the iliac and rectal lymph nodes, causing lymphadenitis, proctitis and perirectitis in that part of the vagina, which can cause clinical blood in the stool, abdominal pain, diarrhea, shortness of breath and back pain, perianal swelling, fistula, rectal stricture and labia majora and minor labia elephantiasis. 4.Late symptoms After several years or decades, long-term recurrent inguinal lymphadenitis may lead to pubic elephantiasis, rectal stenosis, etc. 5. Systemic symptoms During the period of swelling and suppuration of lymph nodes, there may be systemic symptoms such as chills, high fever, arthralgia, weakness and enlargement of liver and spleen. There are also erythema multiforme, erythema nodosum, conjunctivitis, aseptic arthritis, pseudomeningitis, etc. 1.Serum antibody test Mainly microimmunofluorescence test, enzyme-linked immunosorbent assay, etc. Detection of high titers of anti-chlamydia trachomatis is important for the diagnosis of the disease. 2, chlamydia culture, antigen detection method, nucleic acid detection method chlamydia culture is the most specific method to diagnose the disease, but the sensitivity is not too high. Antigen detection methods such as enzyme immunoassay is relatively simple and rapid, but the sensitivity is also not high. Nucleic acid detection method is very sensitive and specific, can also be used for the laboratory examination of the disease. 3, histopathological examination There are relatively specific histopathological changes of the disease, which have a certain reference value in the diagnosis. It must be noted that: clinically, even if the diagnosis of the disease is established, laboratory tests for syphilis, genital herpes, soft chancre and other ulcerative diseases should be done to exclude the possibility of combining these infections. Diagnosis 1. History of non-marital sexual contact or spousal infection with an incubation period of 5 to 21 days on average. 2. Early appearance of small blisters, erosions or ulcers in the genital area. 3. After a few weeks of infection, swollen lymph nodes, red, swollen, hot and painful inguinal lymph nodes, “groove sign” and most fistulas in the shape of a “squirt pot” in men, and proctitis and perirectitis in women may occur. The clinical manifestations of genital elephantiasis and rectal stricture may appear in the late stage. 4. The characteristic pathological lesion is a stellate pustule in the lymph node. Serum Chlamydia antibody titers are elevated. Serotype L1, L2 or L3 Chlamydia trachomatis is isolated by cell culture. Differential diagnosis The disease often needs to be clinically differentiated from soft chancre, syphilitic inguinal lymph node enlargement, genital herpes, filariasis, and rectal cancer. Treatment The principles of treatment are early treatment, regular and adequate dosage, and treatment with sexual partners. The recommended treatment regimen is as follows: doxycycline, orally, twice daily for 21 days; or erythromycin, orally, four times daily for 21 days; or tetracycline, orally, four times daily for 14-28 days; or minocycline, orally, twice daily for 21 days. The above treatment can be extended according to the condition. For acute inguinal syndrome, fluctuating lymph nodes can be drained with a syringe to remove the pus or incised to prevent the formation of inguinal ulcers. Rectal strictures can be dilated at the beginning, and severe rectal strictures can be treated surgically. Several months or an adequate course of antibiotic therapy must be completed before and after surgery. Sexual partners should be examined and treated. Suspected patients and sexual contacts should be treated promptly. Sexual partners of patients with the disease who have had sexual contact with the patient within 60 days prior to the onset of symptoms must be tested and treated for chlamydia in the urethra and cervix, and antibiotic prophylaxis should be given to those who are not sure to exclude the disease. Prevention Proper use of condoms can play a preventive role. Continuous improvement of hygiene, health education and avoidance of extramarital sexual contact can truly prevent lymphogranuloma venereum.