Newborn Rashes

• Core 1 (Pre-Clerkship) 
  • Biomedical Science 
    • Microbiology I 
      • Gram Positives Part 1: Intro and Streptococci 
        • Newborn infections 
      • Parasitology 
        • TORCH infections 
      • Herpesvirus 
        • HSV 1 and 2, VZV, CMV 
    • Microbiology II 
      • Infection Syndromes 
        • Infections originating in the skin, viral exanthems, infection-related rashes 
    • Viruses/Antivirals 
      • Perinatally acquired infections 
  • Integrative Systems 
    • Dermatology  
      • Intro to Derm 
      • Skin of color 
      • Bacterial diseases 
      • HSV, VZV, and enterovirus 
      • Syphilis 
      • Pediatric derm 
      • Viral exanthems 
• Core 2 (Clerkship)
  • Pediatrics - Rashes Royale in Fever Didactic
• Core 3 (Post-Clerkship)
  • Electives that may further knowledge: NICU, Pediatric Dermatology, 

A 3-day-old newborn presents for a newborn well child check. The parents are concerned about a rash that has developed on her face and trunk. The parents report that the rash appeared suddenly yesterday consists of small, red spots and bumps that have a yellowish-white center. They mention that the rash seems to come and go, and they have not noticed any associated fever or discomfort. 

Onset, Duration, Location, and Progression: 

• When did the rash first appear?  
• Where did the rash start? 
• Has the rash spread? 
• Has the rash improved or worsened?  

Associated Symptoms:  

• Is the rash itchy, painful, or causing discomfort?  
• Any fever, fussiness, or other systemic symptoms?  

Daily Care and Exposures:  

• What products are being used on the baby’s skin (e.g., soaps, lotions, diapers)?  
• What laundry detergents are being used to wash the baby’s clothes? 
• Is the baby exposed to excessive heat or prolonged wet diapers?  
• Does the baby drool a lot? 

Exacerbating or Relieving Factors:  

• Does the rash worsen with heat, moisture, or certain products?  
• Has anything helped improve the rash (e.g., creams, air exposure)?  

Maternal/Pregnancy/Birth History:  

• Any maternal infections, medication use, or complications during pregnancy?  
• Review prenatal screening tests if possible. 
• Was the baby born full term or preterm?  
• Did the baby need to stay in the NICU for any reason? 

Source: https://www.aafp.org/pubs/afp/issues/2015/0801/p211.html

Physical Exam  

Vitals: Are there any associated, concerning vital sign changes? 

General Appearance: Does the baby appear well or in distress? 

Appearance of the Rash:  

• Inspect for rash type (macules, papules, pustules, vesicles, scales, or plaques) 
• Assess rash distribution and pattern (focal vs. generalized) 

Areas of Involvement:  

• Check common areas like the scalp, face, diaper region, and skin folds.  

Associated Findings:  

• Look for erythema, scaling, satellite lesions (suggesting fungal infection), or excoriations.  

Systemic Signs:  

• Evaluate for fever, irritability, or other signs of systemic illness, which may indicate a more serious condition.  

Pearls 

1. The majority of newborn rashes appear within the first 72 hours of life are typically self-limiting, so reassurance to parents is a key part of management.  
2. Understanding the differences between neonatal rashes is crucial for appropriate diagnosis and management. For example, while erythema toxicum is benign, conditions like neonatal herpes simplex virus infection can be serious and require immediate evaluation and treatment. 
3. When assessing rashes in newborns, it's essential to consider daily care practices, including the use of soaps, lotions, and diapers, as well as environmental factors like heat and moisture. This can help identify potential irritants or exacerbating factors for conditions such as diaper dermatitis and drool dermatitis. 

• Newborn Skin: Part I. Common Rashes (AAFP) 
• Newborn Skin: Part I. Common Rashes and Skin Changes (AAFP) 
• Newborn Skin: Part II. Birthmarks (AAFP) 
• Newborn Nursery Photo Gallery by Stanford Medicine 

Answer 1:

Correct Answer: b. Erythema Toxicum Neonatorum 

Erythema Toxicum Neonatorum (ETN) is a benign, self-limited skin condition seen in up to 50% of full-term newborns. It typically appears within the first few days of life (often day 2–5). Lesions are characterized by erythematous macules, papules, and pustules that may resemble a "flea-bitten" appearance. The palms and soles are typically spared, and the baby appears well. Diagnosis is clinical, and no treatment is necessary. Lesions usually resolve spontaneously within 1–2 weeks. 

Incorrect Answers: 

a. Neonatal Herpes Simplex Virus (HSV)

HSV can present with vesicular lesions, not papules and pustules, and is often associated with systemic symptoms such as lethargy, fever, seizures, or poor feeding. HSV lesions may also involve the scalp or mucous membranes and are a medical emergency requiring antiviral treatment.

c. Miliaria Rubra (Heat Rash)

Miliaria results from sweat gland obstruction and is typically seen in warm, humid environments. It presents as tiny erythematous papules or vesicles, often in areas of occlusion (e.g., neck, axillae, groin), not widespread pustules on an erythematous base.

d. Transient Neonatal Pustular Melanosis

This condition can present at birth and features superficial pustules that rupture easily, leaving behind hyperpigmented macules. Unlike ETN, it commonly involves the palms and soles and lacks the erythematous base. 

Answer 2

Correct Answer: b. Send HSV PCR from multiple sites including blood and cerebrospinal fluid (CSF) 

This presentation is classic for neonatal herpes simplex virus (HSV), which often includes: 

• Vesicular rash in clusters 

• Mucocutaneous involvement 

• Lethargy and poor feeding (suggesting potential CNS or disseminated disease) 

• Limited prenatal care, which increases risk of undiagnosed maternal HSV 

The appropriate next step is to evaluate for HSV infection with PCR testing from: 

• Lesions 

• Blood 

• Cerebrospinal fluid (CSF) 

This approach allows identification of SEM, CNS, or disseminated disease, all of which may occur without all three systems being involved initially. Empiric IV acyclovir should also be initiated promptly while awaiting results. 

Incorrect Answers:

a. Perform skin biopsy to confirm the diagnosis

Invasive and not necessary when less invasive, more accurate PCR is available. Biopsy is not first-line in neonatal HSV evaluation.

c. Start empiric antibiotics for presumed bacterial sepsis

While neonatal sepsis is in the differential and empiric antibiotics are often started alongside other measures, this does not address the key diagnostic concern here, which is HSV. Antibiotics alone won’t help HSV and should not delay antiviral evaluation and treatment. Note: In real clinical settings, antibiotics may still be initiated concurrently until HSV and bacterial causes are ruled out, but they are not the diagnostic step being asked here.

d. Provide reassurance given the self-limiting course:

This is incorrect and potentially dangerous. Neonatal HSV can be rapidly progressive and fatal. Immediate evaluation and treatment are essential. 

Basic Dermatology: Newborn Skin Disease 1: Birthmarks (Cases and Questions) (American Academy of Dermatology) 

Basic Dermatology: Newborn Skin Disease 2: Rashes (Cases and Questions) (American Academy of Dermatology)