Syphilis is a sexually transmitted infection (STI) caused by the spirochete bacterium Treponema pallidum. It is characterized by a chronic intermittent clinical course. Treponema pallidum is transmitted person to person via direct contact with a syphilis ulcer during vaginal, anal, or oral sex and may enter through skin or mucous membranes. Hence, the locations for syphilitic ulcers include the vagina, cervix, anus, rectum, lips, hands, and inside of the mouth.
In the primary stage of syphilis, a painless ulceration, or chancre, typically appears about 21 days after initial infection, often preceded by a firm, painless papule. The chancre may be difficult to observe if located in the vagina or on the cervix. The entire genital area is susceptible, including the anus and inside the urethra. Chancres are typically asymptomatic. If secondary erosion or fissuring occurs, they may be painful. Other symptoms may include bloody stool and rectal pain.
Chancres vary in size from a few millimeters to several centimeters. They have an incubation period of 10-90 days (average 21 days). The chancre lasts 3-6 weeks and heals spontaneously.
All patients with primary syphilis will go on to develop secondary syphilis if the condition is left untreated. Secondary syphilis usually appears 3-10 weeks after the primary chancre and is characterized by a papulosquamous eruption and mucosal involvement, in some cases. Tertiary syphilis may appear months to years after secondary syphilis resolves and can involve the central nervous system (CNS), heart, bones, and skin.
Ocular screening (eg, slit lamp examination) is advised for patients with suspected or proven syphilis.
Immunocompromised patient considerations: Genital ulcers caused by syphilis increase the risk of HIV transmission due to epithelial barrier compromise and increased numbers of macrophages and T-lymphocytes with HIV-specific receptors.
HIV infection can alter the clinical presentation of syphilis. Manifestations include multiple chancres, atypical cutaneous eruptions, increased severity of organ involvement (such as hepatitis and glomerulonephritis), and rapidly developing arteritis and neurosyphilis. Neurosyphilis can occur at any stage of syphilis.
Related topics: ocular syphilis, endemic syphilis
Primary syphilis - Anogenital in
See also in: Overview,Oral Mucosal LesionAlerts and Notices
Synopsis
Codes
ICD10CM:
A51.0 – Primary genital syphilis
SNOMEDCT:
266127002 – Primary syphilis
A51.0 – Primary genital syphilis
SNOMEDCT:
266127002 – Primary syphilis
Look For
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Diagnostic Pearls
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Differential Diagnosis & Pitfalls
All patients with a genital ulcer should have serologic testing for syphilis. The following differential will be focused on the chancre of primary syphilis.
Infectious:
Infectious:
- Genital herpes simplex virus – Look for multiple small vesicles on an erythematous base; usually painful.
- Chancroid (Haemophilus ducreyi) – Multiple nonindurated ulcers with irregular, ragged undermined edges; very painful; yellow exudate commonly present.
- Lymphogranuloma venereum (Chlamydia trachomatis serovars L1-3) – Ulcers usually not observed but can be small, shallow, and painless; often transient.
- Granuloma inguinale (Klebsiella granulomatis) – Painless, extensive, and progressive; looks like granulation tissue.
- Ecthyma gangrenosum – Ulcers are necrotic and rapidly increase, commonly on extremities and trunk.
- Monkeypox – Lesions beginning in the genital and anal area have been reported.
- Amebiasis – Starts as a vesicle that ulcerates; typically painful with undermined edges; can have purulent exudate.
- Genital trauma – Preceded by known insult; erosions are more geometric and painful.
- Fixed drug eruption – Red-brown papules or annular plaques; can progress to bullae and erosions mimicking syphilis. Recurrent lesions are always located at the same site.
- Behçet disease – Associated with recurrent oral ulceration, genital ulceration, and ocular abnormalities.
- Ulcerative genital squamous cell carcinoma
- Contact dermatitis – Preceded by exposure to irritant; progression to ulceration would be unusual and indicates severe disease.
- Calciphylaxis – May rarely present with tender ulceration on genital skin, occurs in patients with renal failure.
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Management Pearls
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Therapy
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References
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Last Reviewed:08/24/2020
Last Updated:05/30/2022
Last Updated:05/30/2022
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Primary syphilis - Anogenital in
See also in: Overview,Oral Mucosal Lesion