Erythema toxicum neonatorum

Background

Normal dermal anatomy.

• Most common benign rash of newborns, occurring in ~50% of full-term neonates
• Self-limited condition lasting ~1-2 weeks
• Etiology unclear; thought to be related to activation of the innate immune system at hair follicles
• Onset typically 24-72 hours after birth, but can appear up to 2 weeks of age
• Incidence declines with decreasing gestational age (rare in preterm infants)

Clinical Features

Erythema toxicum

• Erythematous macules, papules, and pustules on a blotchy erythematous base
• Distribution: face, trunk, proximal extremities
• Spares palms and soles (key distinguishing feature)
• Lesions are evanescent — appear, fade, and reappear in different locations over hours to days
• Infant is well-appearing, afebrile, feeding normally

Differential Diagnosis

Neonatal Rashes

• Acne
• Atopic dermatitis
• Candidiasis
• Contact dermatitis
• Diaper dermatitis
• Erythema toxicum neonatorum
• Impetigo
• Mastitis
• Milia
• Miliaria
• Mongolian spots
• Omphalitis
• Perianal streptococcal dermatitis
• Psoriasis
• Pustular melanosis
• Seborrheic dermatitis
• Sucking blisters
• Tinea capitis
• Key differentials to consider:
  • Neonatal HSV: clustered vesicles, ill-appearing infant, fever
  • Staphylococcal scalded skin syndrome: widespread erythema, skin tenderness, desquamation
  • Transient neonatal pustular melanosis: pustules on non-erythematous base, present at birth

Evaluation

• Clinical diagnosis in a well-appearing neonate
• If diagnosis uncertain: Wright stain of pustule contents shows eosinophils (pathognomonic)
• No labs, cultures, or imaging needed if classic presentation

Management

• No treatment necessary — reassurance to parents
• Resolves spontaneously within 1-2 weeks without sequelae

Disposition

• Discharge with parental reassurance
• No follow-up needed unless atypical features

See Also

• Neonatal rashes
• Transient neonatal pustular melanosis