A 3-hours-old neonate is evaluated in the newborn nursery for “facial bumps” which the newborn’s mother just noticed. The newborn’s mother received all routine prenatal care and her pregnancy was uncomplicated. Birth history is significant for delivery at 39 weeks and 4 days via normal spontaneous vaginal delivery after 13 hours of labor. Forceps were used during the deliver due to maternal exhaustion. Examination of the newborn in the first 10 minutes of life did not reveal any lacerations. Vital signs are within normal limits. Physical examination reveals a vigorous newborn with diffuse, 1mm, firm, white papules on the face.
Which of the following additional features is most likely related to this newborn’s physical examination findings?
A) Accumulation of keratin
This baby’s skin findings likely represent milia, which are small epidermal inclusion cysts. Milia are present on the skin of roughly half of term newborns and do not require any intervention. They are self-resolving, and parents should be reassured.
Answer choice B: Eosinophilia on smear of the lesions, is incorrect. This is a feature of erythema toxicum neonatorum, which is a benign transient pustular eruption usually found in healthy term infants. Lesions typically arise on diffuse areas of the body between days zero and three of life, usually sparing the palms and soles.
Answer choice C: Exposure to excess heat, is incorrect. This is a risk factor for miliaria rubra, otherwise known as heat rash. Miliaria rubra can occur at any age but cannot be present at birth as pathogenesis is related to occlusion of eccrine sweat ducts in warm environments.
Answer choice D: Exposure to Malassezia, is incorrect. This is a feature of neonatal cephalic pustulosis, previously known as neonatal acne but no longer called such due to lack of androgen involvement. Neonatal cephalic pustulosis usually occurs around three weeks of age.
Answer choice E: Exposure to the herpes simplex virus in utero, is incorrect. Congenital herpes simplex virus infection is more likely to presents with clusters of vesicular lesions on the skin. In severe cases, central nervous system infection and multiorgan disease can also occur. This infant appears healthy, and HSV positivity would have likely been identified in this mother who received all routine prenatal care.
Key Learning Point
Milia are epidermal inclusion cysts that do not require clinical intervention and are self-resolving. Unlike many other neonatal rashes such as erythema toxicum, miliaria rubra, and neonatal cephalic pustulosis, milia can be present at birth.
