Erythema toxicum neonatorum
Background
- 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
- 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