Differential Diagnosis for a 2-Day-Old Boy with a Diffuse Rash
- Single Most Likely Diagnosis
- Erythema toxicum neonatorum: This condition is a common, benign rash that appears in the first few days of life, characterized by erythematous macules, papules, and pustules, which matches the patient's presentation. It is self-limiting and resolves without treatment.
- Other Likely Diagnoses
- Transient neonatal pustular melanosis: This condition presents with pustules and vesicles, primarily on the face, neck, and extremities, but can also appear on the trunk. It is more common in African American infants but can occur in any ethnicity.
- Neonatal acne: Although less common at 2 days of age, neonatal acne can present with comedones, papules, and pustules, typically on the face. However, the distribution in this case is more widespread.
- Do Not Miss Diagnoses
- Herpes simplex virus (HSV) infection: Given the maternal history of cold sores, there is a risk of neonatal HSV infection, which can present with skin, eye, and mouth lesions, or disseminated disease. Early recognition and treatment are crucial to prevent severe outcomes.
- Congenital syphilis: This condition can cause a variety of skin rashes, including maculopapular or papulosquamous lesions, and is critical to diagnose due to the potential for severe complications if left untreated.
- Rare Diagnoses
- Incontinentia pigmenti: A genetic disorder that can cause skin lesions, including blisters and pustules, typically following the lines of Blaschko. It is rare and often associated with other systemic findings.
- Listeriosis: Although rare, neonatal listeriosis can cause a petechial or papular rash, among other symptoms, and is important to consider, especially if the infant is ill-appearing or has other signs of infection.