Syphilis - the secondary rash

syphilis · secondary syphilis · the great imitator · lues · chancre

A non-itchy rash involving the palms and soles - regularly missed, and diagnoses in the UK have been climbing for a decade on UKHSA surveillance.

URGENT DERMBand C

Red flags

Neurological symptoms, visual change or hearing loss - neurosyphilis and ocular or otosyphilis can occur at any stage and need urgent specialist management
Pregnancy - congenital syphilis is preventable and this needs same-day specialist involvement
HIV co-infection - test for it in every case; the two travel together and co-infection alters management
Any painless genital ulcer, which is syphilis until proven otherwise
A patient who cannot be contacted for results - make the referral pathway robust before they leave

Recognise

On light skin

Coppery-red or ham-coloured symmetrical macules and papules on the trunk, palms and soles, non-itchy, sometimes scaly, with moist wart-like condylomata lata in the flexures.

On brown and black skin

The coppery or ham-red colour on which the classic description rests is not perceptible in brown and black skin, where lesions more often appear as hyperpigmented, violaceous or dusky macules and papules, and annular forms are often said to be commoner in patients with darker skin, though that is not cited here because it could not be traced to a source read in full - treat it as a reason not to expect the textbook picture rather than as an established fact. The reliable features are distributional and symptomatic rather than chromatic: a symmetrical eruption involving the palms and soles that does not itch, with generalised lymphadenopathy. Examine the palms and soles deliberately in any unexplained widespread rash, and take a sexual history rather than relying on appearance.

In any skin tone

Palms and soles involved - very few rashes do this, and it should trigger the thought
Not itchy - which separates it from most widespread eruptions
Symmetrical and widespread
Generalised lymphadenopathy, sometimes with fever, sore throat, malaise and patchy hair loss
A preceding painless genital, oral or anal ulcer weeks earlier that healed without treatment - often not volunteered, so ask
Condylomata lata: moist, flat, wart-like plaques in the flexures, highly infectious

Distribution

Widespread symmetrical eruption on the trunk and limbs that characteristically involves the palms and soles - one of very few rashes that does. Primary disease is a solitary painless ulcer at the site of inoculation.

Photographs

Secondary syphilis on the sole of a Black patient. Scattered dusky coppery-brown macules and papules, some scaly, across the plantar surface. **A rash that involves the palms and soles is syphilis until proven otherwise** - very few other things do it. On black skin the classic 'coppery' colour reads as a darker brown than the surrounding sole rather than as anything red, so look for the change in shade and the scale rather than for erythema. Ask about a painless ulcer weeks earlier, and test.
Fitzpatrick VI (Fitzpatrick type estimated from the photograph, not stated by the source) · CDC Public Health Image Library · Wikimedia Commons - Secondary stage syphilis sores (lesions) on the soles of the feet. Plantar lesions-CDC.jpg · Public domain

Provenance for every photograph in this library: image licences. How much of the corpus still has no darker-skin photograph: skin tone coverage.

Mimics

DRESS - drug reaction with eosinophilia and systemic symptoms — Both give a widespread eruption with systemic features; syphilis is not itchy, involves palms and soles, and has no drug latency
Measles — Measles is febrile with coryza and cough and a descending rash; syphilis has palms and soles and no prodrome
Herpes simplex — A painful grouped vesicular genital lesion is herpes; a solitary painless indurated ulcer is syphilis
Parvovirus B19 (slapped cheek disease) — Both can give a widespread symmetrical rash with arthralgia in adults

What to do in the ED

Examine the palms and soles in every unexplained widespread rash, and ask about a preceding painless ulcer
Take blood for syphilis serology and offer HIV testing at the same time
Refer to sexual health services urgently - they manage treatment, partner notification and follow-up serology, and an ED diagnosis without that referral achieves little
Do not start treatment in the ED without specialist discussion; staging determines the regimen
Ask about pregnancy and involve obstetrics the same day if relevant
Ask directly about visual, hearing and neurological symptoms, which change the urgency completely
Give clear written information about how results will reach them and what happens next
In anyone under 18, syphilis is a safeguarding matter as well as a clinical one. The entry is written for adults, but a sexually active 16- or 17-year-old is exactly the patient in whom it is missed - take a confidential history, consider exploitation and coercion, and follow your local safeguarding route alongside the sexual health referral. In a child, involve paediatrics and safeguarding the same day

Disposition

URGENT DERM

Urgent sexual health referral rather than dermatology in most cases - the entry is filed as derm-urgent because this tool has no disposition value for urgent sexual health; read it as the urgency, not the specialty. Same-day specialist involvement for pregnancy, or for neurological, ocular or auditory symptoms.

Safety-netting

It is important that you attend the sexual health appointment - this is very treatable, but it does not go away on its own even though the rash will fade by itself. Return or seek urgent advice if your vision or hearing changes, if you develop a severe headache, or if you become unwell. Recent sexual partners will need testing too, and the clinic will help you with that confidentially.

Local variation

Whether the ED takes serology or defers all testing to sexual health varies; know your local pathway so the patient is not lost between services.

Sources

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