Sexual health

The Rare Genital Ulcers Beyond Herpes and Syphilis

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Chancroid causes a painful ulcer with tender, swollen groin nodes. LGV often starts as a small ulcer easy to miss, followed by painful lymph nodes or, increasingly recognized in the U.S., rectal symptoms. Granuloma inguinale is slow-growing, painless, and bleeds easily. All three need a swab and a lab that specifically tests for them — a standard STI panel does not automatically include any of the three.

Last updated: July 2026

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What sets these three rare ulcer diseases apart from herpes and syphilis?

Chancroid, lymphogranuloma venereum, and granuloma inguinale are three bacterial causes of genital ulcers that are far less common in the United States than herpes or syphilis, but CDC's STI treatment guidelines cover all three alongside the more familiar infections, because a genital sore differential that stops at herpes and syphilis will miss them 1. Each has a different look, a different cause, and needs its own specific test.

Genital herpes, the most common cause of genital ulcers overall, is a lifelong viral infection that has no cure but is manageable with antiviral medication and can be transmitted even when no sore is visible 2. Syphilis follows a staged pattern, and its first-stage sore, called a chancre, is classically a single, painless ulcer that can go unnoticed and heals on its own even without treatment, which is part of why it is so often missed 3. Chancroid, LGV, and granuloma inguinale each share some individual features with those two — a painless sore here, painful lymph nodes there — but none follows the herpes or syphilis pattern exactly, and each is caused by a different organism.

Chancroid: a painful ulcer with tender, swollen lymph nodes

Chancroid produces one or more soft, painful ulcers on the genitals, often with ragged edges and a grayish base, usually appearing within about a week of exposure and frequently accompanied by painful, swollen groin lymph nodes that can develop into a fluctuant, pus-filled swelling called a bubo. The pain is the clue that separates it from syphilis, whose primary sore is classically painless 3.

Chancroid is rare in the United States, with only a small number of cases reported most years, and it is more commonly diagnosed in travelers returning from parts of Africa, Asia, the Caribbean, and Latin America where it circulates more widely. Because the bacterium that causes it, Haemophilus ducreyi, is difficult to grow in a lab culture, diagnosis in practice often relies on the clinical picture — a painful ulcer plus tender groin nodes, with herpes and syphilis ruled out by their own tests — rather than a positive culture alone. Anyone being evaluated for painful sores on the penis after travel to a higher-prevalence region should mention that travel specifically, since it changes which tests get ordered.

Lymphogranuloma venereum (LGV): a small ulcer that's easy to miss

LGV often begins as a small, painless bump or ulcer that can go completely unnoticed and heals on its own within days, which is part of why it is frequently diagnosed only after the second stage — painful, swollen lymph nodes in the groin or, especially among men who have sex with men, rectal pain, discharge, and bleeding from proctitis. Because the ulcer itself is so easy to miss, LGV is usually caught by its later symptoms rather than the sore that started it 1.

LGV is caused by specific strains of Chlamydia trachomatis — the same bacterium behind ordinary chlamydia, but a different, more invasive set of strains that spread into lymph tissue rather than staying at the surface. In the U.S., LGV proctitis has been increasingly recognized among men who have sex with men, which is one reason clinicians now consider it specifically rather than assuming rectal symptoms are routine gonorrhea or chlamydia. Because LGV is a chlamydial infection, doxy-pep — a preventive dose of the antibiotic doxycycline taken after sex, which CDC recommends for some people at ongoing risk to lower rates of chlamydia, gonorrhea, and syphilis — is sometimes discussed as a way to reduce LGV risk too, though it has not been specifically studied for that purpose 4.

Granuloma inguinale (donovanosis): slow, painless, and prone to bleeding

Granuloma inguinale, also called donovanosis, causes a slow-growing, painless ulcer with a beefy-red, granular surface that bleeds easily when touched, unlike the more contained sores of chancroid or syphilis. It is caused by the bacterium Klebsiella granulomatis and is now rare worldwide, largely confined to specific regions of India, southern Africa, South America, and parts of Australia and Papua New Guinea, with only occasional cases reported elsewhere 1.

Because it grows slowly and does not hurt, donovanosis is often not recognized as an infection right away; the ulcer can persist and gradually enlarge over weeks without treatment, and without a biopsy or specific lab test it can be mistaken for other slow-growing skin conditions. A tissue sample, not the appearance alone, is what reliably confirms it.

Reducing risk and getting the right test

Condoms lower the risk of chancroid, LGV, and granuloma inguinale, since correct, consistent use is highly effective against infections spread through genital fluids but provides only partial protection against infections spread through skin-to-skin contact — a category that includes ulcer diseases whose sores can sit outside the area a condom covers 5. That partial protection is one reason clinicians pair prevention counseling with a lower threshold for testing when a new ulcer shows up alongside a relevant travel or partner history.

Broader STI screening is worth asking about at the same visit. National guidelines recommend syphilis testing for people at increased risk regardless of symptoms 6, and mentioning travel to a region where chancroid, LGV, or donovanosis is more common — or a partner from one — gives a clinician the specific reason needed to add those tests rather than defaulting to a standard panel that may not include them.

Getting diagnosed and treated

All three of these infections are bacterial and treatable with a course of antibiotics once identified, and treatment guidance for each sits inside the same CDC framework used for more common STIs 1. Because misdiagnosis is common when a sore does not fit a familiar pattern, an ulcer that persists, that does not look like typical herpes or syphilis, or that develops painful groin swelling is worth a specific evaluation rather than a wait-and-see approach.

All three conditions respond to the correct antibiotic course once identified, and none carries the uncertainty of an untreatable diagnosis once the right test result is in hand. Anyone with a genital ulcer who has traveled recently, or whose partner has, should mention that specifically — it is often the detail that changes which tests get ordered in the first place.

Common questions

No. All three are rare in the U.S. compared with herpes, syphilis, chlamydia, and gonorrhea, and most U.S. cases are linked to travel to a region where they circulate more widely, or to specific sexual networks. Their rarity is exactly why they are easy to miss: a routine STI panel does not automatically test for any of them.

Herpes typically causes a cluster of small, painful blisters that break open into shallow sores, often recurring at the same site over time. Chancroid usually causes one or a few deeper, ragged-edged ulcers with painful, swollen groin lymph nodes, and it does not recur the way herpes does once it is treated.

Yes. Because it grows slowly and does not hurt, donovanosis can resemble other slow-growing skin conditions, and a biopsy or specific lab test is usually needed to tell it apart from those rather than relying on appearance alone. It is one reason a persistent, painless, bleeding ulcer deserves a specific evaluation.

No. LGV can also present as a small ulcer with painful groin lymph nodes on the genitals themselves, without ever involving the rectum. Rectal symptoms are more specifically associated with LGV proctitis, which has been increasingly recognized among men who have sex with men in recent years.

Yes. Because all three are bacterial infections passed through sexual contact, a recent partner typically needs evaluation and often treatment as well, similar to the partner-notification approach used for chlamydia, gonorrhea, and syphilis. A clinician who diagnoses one of these three can advise on how far back that outreach should go.

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When a genital ulcer needs prompt evaluation

  • —An ulcer with fever, chills, or feeling unwell beyond the local area
  • —Painful, rapidly enlarging groin swelling, which can indicate a bubo that needs draining
  • —An ulcer that keeps growing or spreading after a course of treatment
  • —Heavy or persistent bleeding from the ulcer itself

Fever, spreading groin swelling, or an ulcer that is rapidly worsening are reasons to be seen the same day rather than wait for a scheduled appointment.

This describes general patterns of three uncommon genital ulcer diseases; it is educational information, not a diagnosis. Only an exam and the specific lab test for each organism can identify which infection is actually present.

References

  1. 1.Workowski KA, Bachmann LH, Chan PA, et al. (Centers for Disease Control and Prevention) (2021). Sexually Transmitted Infections Treatment Guidelines, 2021. MMWR Recommendations and Reports, Vol. 70, No. 4. doi:10.15585/mmwr.rr7004a1 ✓Used here as the source of record for CDC's comprehensive diagnostic and treatment framework, which covers chancroid, LGV, and granuloma inguinale alongside more common STIs.
  2. 2.Centers for Disease Control and Prevention (2024). About Genital Herpes. CDC (cdc.gov/herpes). linkSupports that genital herpes is a viral infection with no cure that is manageable with antivirals and can be transmitted without visible symptoms, used here as a comparison point against the rarer bacterial ulcer diseases.
  3. 3.Centers for Disease Control and Prevention (2024). About Syphilis. CDC (cdc.gov/syphilis). linkSupports the staged natural history of syphilis, including that the primary-stage chancre is classically a single, painless sore, used here to contrast with the painful ulcer of chancroid.
  4. 4.Bachmann LH, Barbee LA, Chan P, et al. (Centers for Disease Control and Prevention) (2024). CDC Clinical Guidelines on the Use of Doxycycline Postexposure Prophylaxis for Bacterial Sexually Transmitted Infection Prevention, United States, 2024. MMWR Recommendations and Reports, Vol. 73, No. 2. doi:10.15585/mmwr.rr7302a1 ✓Supports that CDC recommends doxycycline taken after sex to lower rates of chlamydia, gonorrhea, and syphilis in some populations at ongoing risk, used here to note that this may plausibly extend to LGV given its chlamydial cause, without claiming it has been specifically studied for that use.
  5. 5.Centers for Disease Control and Prevention (2024). Condom Use: An Overview. CDC (cdc.gov/condom-use). linkSupports that condoms are highly effective against fluid-borne infections but provide only partial protection against infections spread by skin-to-skin contact, used here to explain limited but real protection against these ulcer diseases.
  6. 6.US Preventive Services Task Force (2022). Syphilis Infection in Nonpregnant Adolescents and Adults: Screening. US Preventive Services Task Force (reaffirmation, JAMA 2022). PMID 36166020 ✓Supports the recommendation to screen for syphilis in people at increased risk regardless of symptoms, used here to encourage broader STI testing alongside evaluation of a rare ulcer.

6 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — citations link their sources. Editorial policy

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