Erythema toxicum neonatorum

Erythema neonatorum toxicum, toxic neonatal exanthema, urticaria neonatorum, toxic erythema of the newborn, "flea-bite rash".

Benign, self-limiting neonatal exanthematic clinical picture with transient erythematous macules, papules and sterile pustules. Occurs typically within the first few days of life in healthy, mature newborns. Spontaneous healing after 1-2 weeks without consequences.

• Prevalence 30-70 % in mature newborns.
• Premature babies rarely affected.
• More common with higher gestational age and birth weight.
• Minimal or inconsistent gender differences.
• Possibly diagnosed less frequently with dark skin color.

Probably excessive innate immune reaction to initial microbial skin colonization. Perifollicular inflammatory reaction with eosinophilic dominance. Commensal bacteria (e.g. coagulase-negative staphylococci) could act as a trigger. Follicular localization explains exclusion of the palms of the hands and soles of the feet (hairless areas).

• Onset usually 2nd-3rd day of life, rarely immediately postpartum or delayed.
• Fleeting erythematous macules, papules and sterile, yellow-white pustules on a red background.
• Distribution: face, trunk, proximal extremities. Palms and feet omitted.
• Efflorescences variable, asymptomatic (no itching, no pain).
• General condition always unimpaired.

• Clinically typical lesions, onset in the neonatal period, no systemic expression of disease.
• Optional: Smear with detection of sterile pustules with eosinophilic granulocytes.
• Biopsy only useful in case of doubt (perifollicular eosinophilic infiltrate).

• Mainly face (cheeks), trunk (abdomen, back) and proximal extremities.
• Always omitted: palms of hands, soles of feet (missing hair follicles).
• No mucosal involvement, no dermatomal arrangement.

• Healthy, full-term newborn, good general condition.
• Sudden onset of exanthema on the 2nd-3rd day of life, rapid changes in the course of the disease.
• No evidence of infections or maternal diseases.

• Perifollicular inflammation with eosinophilic granulocytes.
• Sterile subcorneal pustules with eosinophilic dominance.
• Intact epidermis, no acantholysis, no spongiosa edema.
• Immunohistochemically elevated inflammatory markers (E-selectin, IL-8, eotaxin).

None. Only unnecessary diagnostic or therapeutic measures due to misinterpretation are dangerous.

Excellent. Recovery within 1-2 weeks without scars or residuals.

Not possible and not necessary.

No causal therapy required. Important: reassure and educate parents.
General measures: mild cleansing, keep skin dry, avoid mechanical irritation.

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