In a healthy term newborn with a fascial‑ring type erythema, what is the most likely diagnosis and recommended management?

Fascial Ring Type Erythema in Newborn

Most Likely Diagnosis

This presentation is most consistent with erythema toxicum neonatorum (ETN), a benign, self-limited condition that requires no treatment beyond parental reassurance. 1, 2

Clinical Characteristics

ETN typically presents with the following features:

• Onset within first 48 hours of life (though can appear up to first week) 1, 3
• Characteristic lesions include erythematous macules with central wheals, papules, or pustules creating the "fascial ring" or target-like appearance 1, 4
• Most common in healthy, term newborns 4, 3
• Distribution typically on trunk, face, and proximal extremities (spares palms and soles) 2, 3
• Lesions are transient, migrating and resolving spontaneously within 5-7 days without sequelae 1, 4

Diagnostic Confirmation

If diagnostic uncertainty exists:

• Wright stain of pustule contents reveals abundant eosinophils (not neutrophils), confirming the diagnosis 1, 5
• No bacterial, viral, or fungal organisms present on culture or microscopy 2, 5
• Histology shows eosinophilic infiltration if biopsy performed (rarely necessary) 1

Critical Differential Diagnoses to Exclude

While ETN is benign, you must differentiate from potentially serious conditions:

Infectious Pustular Dermatoses (Require Immediate Treatment)

• Bacterial sepsis with skin manifestations - look for systemic signs (fever, lethargy, poor feeding, hypotension) 5, 3
• Herpes simplex virus infection - presents with grouped vesicles on erythematous base, often with systemic illness 5, 3
• Candida infection - satellite pustules around erythematous plaques, typically in diaper area 3

Other Benign Pustular Conditions

• Transient neonatal pustular melanosis - present at birth (not 48 hours later), leaves hyperpigmented macules after pustules rupture 2, 5
• Miliaria pustulosa - occurs in intertriginous areas after fever/overheating 5, 3

Recommended Management

No treatment is necessary for ETN beyond observation and parental education. 1, 2

Specific Management Steps:

1. Provide parental reassurance that this is a benign, self-limited condition requiring no intervention 2, 3

2. Educate parents that lesions will spontaneously resolve within one week without scarring 1, 4

3. Avoid unnecessary interventions - no topical medications, antibiotics, or diagnostic testing needed for classic presentation 2, 5

4. Observe for resolution over 5-7 days 1, 4

Red Flags Requiring Further Evaluation

Pursue additional workup if:

• Systemic signs of illness present (fever >38°C, lethargy, poor feeding, respiratory distress, hypotension) - suggests sepsis requiring blood cultures and empiric antibiotics 5, 3
• Lesions present at birth rather than appearing after 24-48 hours - consider transient neonatal pustular melanosis or congenital infections 2, 5
• Pustules persist beyond 7-10 days - obtain Wright stain and cultures to exclude infectious etiology 5, 3
• Grouped vesicles on erythematous base - suggests herpes simplex requiring immediate antiviral therapy 5, 3

Common Pitfalls to Avoid

• Do not initiate empiric antibiotics for classic ETN presentation without systemic signs of infection 2, 5
• Do not perform extensive laboratory workup (blood cultures, skin cultures) in well-appearing infant with characteristic lesions 2, 3
• Do not confuse with serious infections - the key distinguishing feature is the well-appearing infant without systemic symptoms 5, 3