Genital Ulcer Diseases
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Direct answer
Genital ulcer diseases are sexually transmitted infections that break the skin or mucosa of the genitals, and the four classic causes differ mainly in pain, bubo formation and organism. Chancroid is a painful ulcer caused by Haemophilus ducreyi, lymphogranuloma venereum is a painless ulcer with an inguinal bubo caused by Chlamydia trachomatis serovars L1 to L3, donovanosis is a painless beefy-red ulcer caused by Klebsiella granulomatis, and herpes genitalis is a painful vesicular ulcer caused mostly by HSV-2.
What you must remember
- Chancroid: Haemophilus ducreyi causes a painful ulcer with a soft, undermined edge and a tender, suppurating inguinal bubo; the Gram stain shows short Gram-negative rods in a school-of-fish arrangement.
- LGV: Chlamydia trachomatis serovars L1 to L3 cause a small, painless, short-lived ulcer, followed by a painful unilateral or bilateral inguinal bubo with the groove sign.
- Donovanosis: Klebsiella granulomatis causes a painless, beefy-red granulomatous ulcer with a pseudobubo; Donovan bodies lie within large mononuclear cells on a tissue smear.
- Herpes genitalis: HSV-2 is the commonest cause, producing grouped painful vesicles on an erythematous base that ulcerate; PCR of vesicle fluid is the preferred test.
- Primary syphilis: the chancre is painless, firm and indurated, and the associated bubo is rubbery and non-suppurating.
- Pain and bubo pattern: this two-feature sort separates the four main ulcers before any laboratory test is available.
A stepwise approach to a genital ulcer
Clinicians rarely have a confirmed organism at the first visit, so the approach starts with the bedside features and moves to targeted tests. The steps below mirror the logic used in national syndromic management.
- Check the pain first: A painful ulcer points to chancroid or herpes, while a painless ulcer points to syphilis, LGV or donovanosis.
- Feel the groin: A suppurating, tender bubo favours chancroid or LGV, whereas a firm, non-tender bubo favours syphilis.
- Look at the base: A soft, necrotic base with undermined edges suggests chancroid, while a beefy-red granulomatous base suggests donovanosis.
- Send the right test: Use dark-field or serology for syphilis, PCR for herpes and Chlamydia, and tissue smear or biopsy for donovanosis.
- Treat empirically when the cause is unclear: Syndromic management treats a non-herpetic ulcer for syphilis and chancroid together and a vesicular ulcer for herpes, with LGV covered separately, because a single visit often cannot confirm the cause.
Where the exam tries to catch you
The examiner often gives a painful ulcer and expects you to avoid the reflex answer of chancroid.
- Trap: Calling every painful genital ulcer chancroid Correct: herpes is also painful, so chancroid is separated by its Gram-negative coccobacilli pattern and special culture rather than by pain alone.
- Trap: Diagnosing a painless ulcer with an inguinal bubo as chancroid Correct: LGV and syphilis both give painless ulcers, and the suppurating bubo with groove sign points to LGV.
- Trap: Expecting a Tzanck smear to name the virus Correct: it shows multinucleated giant cells but cannot distinguish HSV from varicella-zoster, so PCR is preferred.
- Trap: Searching for Donovan bodies in neutrophils Correct: they lie inside large mononuclear cells.
Frequently asked questions
Which genital ulcer is painful with a tender, suppurating inguinal bubo?
Chancroid, caused by Haemophilus ducreyi, is the genital ulcer that is painful and associated with a tender, suppurating inguinal bubo. The ulcer has a soft, undermined edge and a necrotic base.
Which Chlamydia serovars cause lymphogranuloma venereum?
Lymphogranuloma venereum is caused by Chlamydia trachomatis serovars L1, L2 and L3. These invasive strains differ from the serovars that cause trachoma and urogenital infection.
Which cells contain Donovan bodies in donovanosis?
Donovan bodies are found within large mononuclear cells in a smear from granulation tissue, and they help diagnose donovanosis. Klebsiella granulomatis is difficult to culture, so tissue smear and PCR are used.
Why is a Tzanck smear limited for herpes genitalis?
A Tzanck smear shows multinucleated giant cells in herpes infection, but it cannot tell HSV from varicella-zoster virus. Viral PCR of vesicle fluid is the preferred test for herpes genitalis.
Which syphilis-based test helps separate primary syphilis from LGV on a bubo?
Syphilitic buboes are firm, rubbery and non-suppurating, whereas LGV buboes suppurate and show the groove sign. Serology for syphilis and NAAT for Chlamydia together separate the two diagnoses.