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Difficulty: MediumPediatric Infectious Diseases

A 48-hour-old full-term male newborn is evaluated in the nursery prior to discharge due to the appearance of a new rash. He was born via an uncomplicated spontaneous vaginal delivery to a 26-year-old primigravid woman. The mother received regular prenatal care, and her screening tests for group B *Streptococcus*, hepatitis B, HIV, and syphilis were negative. She has no history of genital herpes. The infant has been breastfeeding well and has normal urine output and bowel movements. Vital signs show a temperature of 37.0°C (98.6°F), heart rate of 142/min, and respiratory rate of 42/min. Physical examination reveals an alert, vigorous infant. There are numerous blanching, erythematous macules and papules, many of which contain central 1- to 2-mm yellow-white pustules, widely distributed across the chest, back, and proximal extremities. The palms and soles are completely spared. The remainder of the examination is unremarkable. Which of the following is the most appropriate next step in management?

  1. Reassurance and routine newborn careAnswer
  2. B
    Intravenous acyclovir therapy
  3. C
    Intravenous ampicillin and gentamicin
  4. D
    Viral swab of the pustules for herpes simplex virus polymerase chain reaction
  5. E
    Application of topical mupirocin to the lesions

Answer

Reassurance and routine newborn care is the most appropriate management.
The correct approach is reassurance and routine care because the infant has erythema toxicum neonatorum (ETN). ETN is a common, benign rash seen in up to half of all full-term newborns, typically appearing within the first 3 days of life. It presents as erythematous macules and papules that often develop 1- to 2-mm central pustules. The rash classically spares the palms and soles. Because it is completely self-limiting and resolves within a few days to weeks without sequelae, providing reassurance to the parents is the only necessary intervention for an otherwise healthy, asymptomatic infant.

Step-by-Step Solution

1
Analyze the patient's presentation and vital signs.
The infant is 48 hours old, vigorous, feeding well, and has normal vital signs (afebrile).
Determining whether the infant has systemic symptoms is critical to rule out infectious etiologies like neonatal sepsis or systemic viral infections.
2
Characterize the dermatologic findings.
The rash consists of erythematous macules and papules with central pustules on the trunk and extremities, notably sparing the palms and soles.
Specific morphologic features and distribution help differentiate benign neonatal rashes from infectious or pathologic ones.
3
Synthesize findings to establish a diagnosis.
The combination of an asymptomatic, healthy newborn with a pustular rash on an erythematous base sparing the palms and soles is the classic presentation of erythema toxicum neonatorum (ETN).
Recognizing pattern presentation allows for accurate diagnosis without unnecessary testing.
4
Determine the appropriate management.
Observation and reassurance are indicated because ETN is benign and self-resolving.
Avoiding unnecessary invasive tests and antibiotic treatments aligns with proper neonatal care and antimicrobial stewardship.

Key Concept

Erythema toxicum neonatorum is a benign, self-limited rash characterized by erythematous macules with central papules or pustules that spares the palms and soles in a healthy newborn, requiring only reassurance.
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Topics

Pediatric Infectious Diseases

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