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Question

Difficulty: MediumNeonatal Disorders

Match each clinical description of a benign neonatal skin finding to its most accurate diagnosis. Recognizing these normal variants is critical to prevent unnecessary diagnostic interventions and parental anxiety.

  • Scattered erythematous macules and papules with central vesicles, appearing on the trunk at 48 hours of life; microscopic examination of a lesion smear reveals numerous eosinophils.Erythema toxicum neonatorum
  • Superficial vesicopustules present at birth that rupture easily, leaving hyperpigmented macules with a collarette of fine scale; smear reveals numerous neutrophils.Transient neonatal pustular melanosis
  • 1- to 2-millimeter pearly white, dome-shaped papules scattered primarily across the cheeks, chin, and nose of a newborn, caused by retained keratin and sebum.Milia
  • Irregularly shaped, blue-gray, poorly circumscribed macules located over the lumbosacral region in an infant of East Asian descent.Congenital dermal melanocytosis
  • Blanchable, pink-red macular lesions present on the glabella, upper eyelids, and nape of the neck that become more prominent when the infant cries.Nevus simplex

Answer

The correct matches pair each distinct benign neonatal dermatologic presentation with its corresponding diagnosis based on onset time, morphology, and cellular characteristics.
Benign neonatal skin lesions can be correctly diagnosed clinically by synthesizing the age of onset, lesion morphology, anatomic distribution, and—when provided—the microscopic cellular infiltrate. Erythema toxicum neonatorum features eosinophils and delayed onset; pustular melanosis features neutrophils and onset at birth; milia feature retained keratin on the face; congenital dermal melanocytosis features lumbosacral blue-gray pigmentation; and nevus simplex features blanchable capillary beds.

Step-by-Step Solution

1
Analyze the onset timing of the vesicular/pustular rashes.
Rash present at birth points toward transient neonatal pustular melanosis, whereas a rash appearing at 24-48 hours of life points toward erythema toxicum neonatorum.
Timing of onset is a key distinguishing feature between the two most common vesicular/pustular benign rashes in newborns.
2
Identify cellular composition from the vignette descriptions.
Eosinophils confirm erythema toxicum neonatorum, while neutrophils confirm transient neonatal pustular melanosis.
Microscopic evaluation of a Wright-stained smear reliably differentiates these similar-appearing lesions if the clinical picture is ambiguous.
3
Differentiate the localized facial papules and macular lesions.
White keratin pearls identify milia, blue-gray presacral macules identify congenital dermal melanocytosis, and blanchable pink-red vascular spots identify nevus simplex.
These findings are diagnosed purely clinically based on their characteristic color, anatomical location, and blanching characteristics.

Key Concept

Differentiation of benign neonatal dermatologic findings
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Topics

Neonatal Disorders

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