A 14-day-old male neonate is brought to the pediatric clinic by his parents due to a facia… — USMLE Step 2 CK

A 14-day-old male neonate is brought to the pediatric clinic by his parents due to a facial rash that appeared 2 days ago. The infant was born at 39 weeks gestation via uncomplicated vaginal delivery to a 25-year-old primigravida. His birth weight was 3.4 kg (7 lb 8 oz), and Apgar scores were 8 and 9 at 1 and 5 minutes, respectively. The parents report that the infant is breastfeeding vigorously every 2 to 3 hours and produces 6 to 8 wet diapers daily. Maternal history is significant for recurrent genital herpes; she was treated with daily acyclovir starting at 36 weeks gestation and had no active lesions at the time of delivery. Maternal group B Streptococcus screening was negative.

The infant appears comfortable and well-hydrated. Current vital signs are as follows:

Vital Sign	Value
Temperature	$37.1^{\circ}\text{C}$ ( $98.8^{\circ}\text{F}$ )
Heart rate	$145\text{/min}$
Respiratory rate	$42\text{/min}$
SpO₂	$99\%$ on room air

Physical examination reveals multiple $1$ - to $2\text{-mm}$ erythematous papules and pustules predominantly distributed across the cheeks, chin, and forehead. There are no vesicles, comedones, or areas of honey-colored crusting. The lesions lack a broad surrounding area of erythema. The remainder of the physical examination, including a detailed neurologic assessment, is normal.

Which of the following is the most appropriate next step in management?

A
Lumbar puncture, blood cultures, and intravenous acyclovir
B
Wright staining of a lesion smear to identify eosinophils
C
Gram stain of a lesion and initiation of topical mupirocin
Reassurance and daily cleansing with mild soap and waterAnswer
E
Application of a low-potency topical corticosteroid cream

Answer

Reassurance and daily cleansing with mild soap and water

The correct answer is reassurance and daily cleansing with mild soap and water. This patient's clinical presentation is classic for neonatal cephalic pustulosis (previously termed neonatal acne). This benign condition typically presents at approximately 2 to 3 weeks of age with inflammatory papules and pustules that are primarily restricted to the face and scalp. Unlike infantile acne, it lacks true comedones. The condition is thought to be an inflammatory reaction to *Malassezia* species colonization. Because the infant is well-appearing, afebrile, and feeding normally, no invasive workup or pharmacologic intervention is required for this mild presentation. Parents should be reassured that the condition is self-limiting and advised to gently cleanse the area daily with mild soap and water, avoiding oily lotions that can exacerbate the condition.

Step-by-Step Solution

Analyze the timing and morphology of the infant's rash.

The rash appeared at approximately 12 days of life and consists of facial erythematous papules and pustules, lacking vesicles or comedones.

Identifying the primary lesion type and age of onset narrows the differential diagnosis of neonatal rashes.

Evaluate the maternal history and the infant's clinical status.

Despite a maternal history of genital herpes, there were no active lesions at delivery. The infant is afebrile, feeding vigorously, and well-appearing.

This step is critical to rule out life-threatening infectious etiologies, such as neonatal HSV or bacterial sepsis, which would require immediate invasive workup and empiric treatment.

Synthesize the findings to establish the most likely diagnosis.

The clinical picture (onset at ~2 weeks, facial papules/pustules, absence of systemic illness) is classic for neonatal cephalic pustulosis (neonatal acne).

Matching the benign clinical findings with the correct diagnosis prevents unnecessary, invasive, and potentially harmful interventions.

Select the appropriate management strategy for the established diagnosis.

The most appropriate next step is reassurance and daily cleansing with mild soap and water.

Neonatal cephalic pustulosis is a benign, self-limiting inflammatory reaction to Malassezia species that typically resolves without pharmacologic therapy.

Key Concept

Neonatal cephalic pustulosis (neonatal acne) presents at 2 to 3 weeks of age with facial papules and pustules. It is a benign condition managed with reassurance and routine gentle cleansing.

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