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Roseola infantum

roseola · roseola infantum · sixth disease · exanthem subitum · HHV-6

High fever for three to four days in an infant who then improves as a rash appears - the sequence is the diagnosis.

DISCHARGEBand B

Red flags

Recognise

On light skin

Discrete rose-pink macules and papules on the trunk, sometimes with a pale halo, in an infant who is now well and afebrile.

On brown and black skin

A faint pink rash is among the hardest findings to see in brown and black skin and may be entirely undetectable, so the diagnosis rests on the sequence rather than the appearance: several days of high fever in an infant, then abrupt defervescence, then the child looks well. Where a rash cannot be seen, this history in a well, afebrile infant is still the likely explanation - but the reasoning must be explicit, and a rash you cannot see must never be used to reassure yourself about a child who is still febrile or unwell.

In any skin tone

Distribution

Discrete rose-pink macules or maculopapules 2 to 3 mm across, first on the trunk, then spreading to the neck and proximal limbs, appearing as the fever resolves. Often faint and short-lived.

Photographs

Roseola in a toddler, after the fever has broken. Fine pink macules and papules over the trunk, buttocks and limbs, each a few millimetres a
Roseola in a toddler, after the fever has broken. Fine pink macules and papules over the trunk, buttocks and limbs, each a few millimetres across, with normal skin between them. The child is well and the rash appeared as the fever stopped - that sequence, not the rash itself, is what identifies roseola. The only openly licensed photograph found for this entry shows light skin. That is a limitation of this page, not of the disease - a darker-skin photograph is still being sought.
Fitzpatrick II (Fitzpatrick type estimated from the photograph, not stated by the source) · M Davis · Wikimedia Commons - Roseola on a 21-month-old girl.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

What to do in the ED

  1. Confirm the sequence explicitly: was the child febrile before the rash, and are they afebrile now
  2. Confirm the rash blanches. Press it, and document that you did
  3. Assess against NICE NG143 traffic-light criteria - the diagnosis depends on a well child
  4. If a febrile convulsion brought them in, manage that on its own merits and explain the recurrence risk
  5. No investigations or treatment are needed in a well, afebrile infant with a typical sequence
  6. Explain the illness so that the rash, which alarms parents precisely because it appears when the child is recovering, is understood

Disposition

DISCHARGE

Discharge a well, afebrile infant with a typical sequence and a blanching rash. Any deviation from that picture is a paediatric assessment.

Safety-netting

The rash appearing as the temperature settles is the expected pattern and the child should now improve. Return immediately if the fever comes back, if any spots stop fading when pressed with a glass, if the child becomes drowsy, floppy or difficult to wake, if they have a fit, or if they are not drinking.

Sources

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