A baby with a widespread itchy rash

A 7 month old baby presented to the dermatology clinic with a three month history of a widespread, itchy rash, predominantly on the trunk and limbs. The family’s general practitioner had prescribed topical steroids and oral antibiotics to treat the rash, to no avail. The baby was systemically well.

On examination there was a widespread florid polymorphic eruption with erythematous papules, nodules, and coalescing plaques (fig 1). On the hands there were crusted papules over the metacarpophalangeal joints and web spaces. On the soles of both feet there were serpiginous tracts, and dermoscopy showed black dots. There was also facial involvement with a unilateral eruption …