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.

1. Reginatto FP, et al. Epidemiology and predisposing factors for erythema toxicum neonatorum and transient neonatal pustular melanosis: A multicenter study. Pediatr Dermatol. 2017;34(4):422-426.
2. Chadha A, Jahnke MN. Common neonatal rashes: clinical features, differential diagnosis, and management. Pediatr Ann. 2019;48(1):e16-e22.
3. Afra TP, et al. Pustular lesions in the neonate: Focused diagnostic approach based on clinical clues. Indian J Dermatol Venereol Leprol. 2022;88(6):708-716.
4. Alghamdi AM, et al. Etiology, prevalence and clinical signs of erythema toxicum neonatorum. Int J Community Med Public Health. 2022;9(1):364-368.
5. Marchini G, et al. Erythema toxicum neonatorum is an innate immune response to commensal microbes penetrated into the skin of the newborn infant. Pediatr Res. 2005;58(3):613-616.
6. Witmer CP, et al. Early infant risk factors for pediatric eosinophilic esophagitis. J Pediatr Gastroenterol Nutr. 2018;67(4):610-615.
7. Roques E, Ward R, Mendez MD. Erythema Toxicum. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 (as of March 15, 2022).
8. Khan K, Singh S, Quazi S. A cross-sectional study on the prevalence and determinants of various neonatal dermatoses. J Family Med Prim Care. 2023;12(11):2942-2949.
9. Kutlubay Z, et al. Newborn skin: Common skin problems. Maedica (Bucur). 2017;12(1):42-47.
10. Monteagudo B, et al. Prospective study of erythema toxicum neonatorum: epidemiology and predisposing factors. Pediatr Dermatol. 2012;29(2):166-168.