Secondary Syphilis
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Direct answer
Secondary syphilis is the disseminated stage of Treponema pallidum infection, typically appearing six to eight weeks after the chancre first develops. Its hallmark is a generalised, non-itchy rash that often involves the palms and soles, together with mucous patches, condylomata lata and generalised lymphadenopathy. Moth-eaten alopecia is a classic feature of the scalp, and the stage is highly infectious, so prompt diagnosis and treatment are essential.
What you must remember
- Timing: typically six to eight weeks after the chancre appears, and the chancre may already have healed.
- Roseola: faint, salmon-pink macules on the trunk, an early and characteristic rash.
- Papulosquamous rash: generalised, non-itchy scaly papules, with palms and soles often involved.
- Condylomata lata: moist, flat-topped, grey-white papules in warm skin folds such as the genitals and perianal area.
- Mucous patches: greyish-white erosions on mucous membranes, such as the mouth and genitals, which are highly infectious.
- Moth-eaten alopecia: patchy, irregular scalp hair loss with a moth-eaten look.
- Systemic features: generalised, painless lymphadenopathy, with fever, malaise and occasionally hepatitis, meningitis or uveitis.
- Treatment: benzathine penicillin G, given according to the current guidelines for the stage.
Clinical features at a glance
A young adult presents with a generalised, non-itchy rash, patchy hair loss and a painless genital ulcer a few weeks earlier. The table lists the features that should suggest secondary syphilis, and it is the pattern of several features together that makes the diagnosis.
| Finding | Typical site | Diagnostic clue |
|---|---|---|
| Roseola | Trunk and abdomen | Faint, non-itchy salmon-pink macules that appear early |
| Papulosquamous rash | Trunk, limbs, palms and soles | Generalised scaly papules, with palmar and plantar involvement |
| Condylomata lata | Warm skin folds, genitals and perianal area | Moist, flat-topped, grey-white papules that are highly infectious |
| Mucous patches | Mouth, tongue and genital mucosa | Greyish-white erosions on mucous membranes |
| Moth-eaten alopecia | Scalp | Irregular, patchy hair loss with a moth-eaten look |
| Corona veneris | Hairline, forehead and scalp | Papulosquamous lesions along the hairline |
| Generalised lymphadenopathy | Whole body | Non-tender, widespread nodes, often with fever or malaise |
Several of these features resemble other rashes, so the diagnosis rests on serology in a patient who is sexually at risk. Palmar and plantar involvement, mucous patches and moth-eaten alopecia are the most useful clues in an exam.
Where the exam tries to catch you
Most traps involve mistaking the rash for eczema or alopecia areata, or underestimating how infectious the lesions are.
- Trap: calling the rash of secondary syphilis itchy eczema Correct: the rash is typically non-itchy and often involves the palms and soles, a clue to syphilis.
- Trap: assuming moth-eaten alopecia is alopecia areata Correct: the patchy, irregular hair loss of secondary syphilis has a moth-eaten look, unlike the round patches of alopecia areata.
- Trap: missing the infectiousness of mucous patches and condylomata lata Correct: these lesions are highly infectious, so patients should avoid sexual contact until they are treated.
- Trap: expecting a chancre in secondary syphilis Correct: the chancre may have healed by then, so the secondary features guide the diagnosis.
Frequently asked questions
What is the characteristic rash of secondary syphilis?
The rash of secondary syphilis is a generalised, non-itchy papulosquamous eruption that often involves the palms and soles. Faint roseola on the trunk is an additional classic early feature of secondary syphilis.
What is moth-eaten alopecia in secondary syphilis?
Moth-eaten alopecia is patchy, irregular hair loss on the scalp in secondary syphilis. It gives a moth-eaten appearance, which distinguishes it from the round patches of alopecia areata.
Why are condylomata lata important in secondary syphilis?
Condylomata lata are moist, flat-topped, grey-white papules in warm skin folds, and they are highly infectious. Recognising them in secondary syphilis helps prevent transmission to sexual partners.
How is secondary syphilis treated?
Secondary syphilis is treated with benzathine penicillin G, given according to the current guidelines for the stage. Partners should be traced and tested, and HIV testing is advisable because co-infection is common.