Neonatal Dermatology

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Neonatal Skin Physiology & Approach - Tiny Skin Big Changes

  • Thinner epidermis & dermis; fewer cell layers.
  • ↑ Surface area to volume ratio: ↑ drug absorption, ↑ heat/water loss.
  • Immature barrier function: improves over first few weeks.
  • Vernix caseosa: cheesy, white biofilm. Composed of sebum, lanugo, epidermal cells.

    ⭐ Vernix caseosa protects against amniotic fluid maceration and provides innate immunity.

  • Skin pH: ~6.0 at birth, acidifies to 4.5-5.5 (acid mantle).
  • Eccrine glands functional; apocrine glands develop at puberty.
  • Melanocytes present, less active initially. Vernix Caseosa on Newborn Skin

Transient Benign Lesions - Passing Skin Shows

  • 📌 Miliaria: Crystalline Clear, Rubra Red & Rough.
LesionKey FeaturesOnsetResolutionHistology (Key)
Erythema Toxicum Neonatorum (ETN)Flea-bitten rash; spares palms/soles24-48 hrs7-14 daysEosinophils
Transient Neonatal Pustular Melanosis (TNPM)Pustules → scale → pigmented macules; all areasBirthPustules: days; Macules: wks-mthsNeutrophils (no eos)
Milia1-2 mm white keratin cysts; faceBirthWeeksKeratin cysts
Miliaria CrystallinaTiny clear vesicles; non-inflammatoryFirst few wksDaysBlock: Stratum corneum
Miliaria Rubra (Prickly Heat)Red papules/pustules; pruritic; intertriginousFirst few wksDays-wksBlock: Deeper epidermis
Sebaceous Gland HyperplasiaTiny yellow papules; nose, cheeks (maternal androgens)BirthWks-mthsHyperplastic seb. glands
Mongolian SpotsBlue-grey macules; lumbosacral (Asian/African)Birth3-5 yrsDermal melanocytes

Vesiculopustular Eruptions - Bumps & Bubbles Alert

  • Common Benign Conditions (Usually well baby):
    • Erythema Toxicum Neonatorum (ETN): Appears day 2-5. Erythematous macules, papules, pustules ("flea-bitten"). Wright stain: Eosinophils. Resolves spontaneously.
    • Transient Neonatal Pustular Melanosis (TNPM): Present at birth. Fragile pustules rupture → collarette of scale & hyperpigmented macules. Wright stain: Neutrophils. Benign.
    • Miliaria (Crystallina, Rubra, Pustulosa): Due to sweat duct obstruction (heat/humidity). Superficial vesicles or erythematous papules/pustules.
  • Infectious (Potentially Serious - Prompt Diagnosis & Rx Crucial):
    • Neonatal Herpes Simplex (HSV): Grouped vesicles on erythematous base. May be localized or disseminated. Tzanck smear: Multinucleated giant cells. Rx: Acyclovir 20 mg/kg IV q8h. Neonatal Herpes Simplex vesicles on scalp
    • Staphylococcal Pustulosis/Impetigo: Pustules, bullae (Bullous Impetigo if S. aureus produces exfoliative toxin), honey-colored crusts. Gram stain: Gram+ cocci in clusters. Culture. Rx: Antibiotics. Neonatal Staphylococcal Pustulosis on Scalp
    • Neonatal Candidiasis: Erythematous plaques with satellite papules/pustules. Common in intertriginous areas, diaper area. KOH prep: Pseudohyphae, spores. Rx: Topical/Systemic antifungals. Neonatal candidiasis before and after treatment
  • Other: Infantile Acropustulosis (recurrent, intensely pruritic vesicopustules on acral sites).

⭐ Multinucleated giant cells on Tzanck smear are characteristic of Herpes simplex infection.

Birthmarks & Nevi - Marks of Distinction

Common congenital markings; early recognition is key.

BirthmarkKey FeaturesAssociationsManagement Flags
Nevus Simplex (Salmon Patch)Pink macules (eyelids, glabella, nape); fade ~1-2yr-Reassurance
Port-Wine Stain (PWS)Dark red/purple patches; persist, may thickenSturge-Weber (V1/V2), Klippel-TrenaunayOphtho/Neuro consult if V1/V2; Laser
Infantile HemangiomaBright red (superficial), bluish (deep); grow then involutePHACES (📌) (large facial)Propranolol (2-3 mg/kg/day); Ulceration, obstruction
Congenital Melanocytic Nevus (CMN)Brown/black; present at birth; melanoma risk ↑ with sizeNeurocutaneous melanosis (large/multiple)Monitor; Excision for giant CMN (>20cm)
Nevus SebaceusYellowish, waxy plaque (scalp/face); ↑ BCC risk laterSchimmelpenning syndromeMonitor; Excision controversial
Giant congenital melanocytic nevus on infant's back

Superficial infantile hemangioma on infant's forehead

Facial port-wine stain in V1 dermatomal distribution is highly associated with Sturge-Weber syndrome, warranting ophthalmology and neurology evaluation.

📌 PHACES syndrome components:

  • Posterior fossa malformations
  • Hemangiomas (large facial)
  • Arterial anomalies
  • Cardiac defects
  • Eye abnormalities
  • Sternal cleft/Supraumbilical raphe

High‑Yield Points - ⚡ Biggest Takeaways

  • Erythema toxicum neonatorum: Benign rash, eosinophils on smear; spares palms/soles.
  • Transient Neonatal Pustular Melanosis (TNPM): Pustules to collarettes of scale, hyperpigmentation; neutrophils on smear.
  • Milia: Common, tiny white keratin-filled cysts; resolve spontaneously.
  • Miliaria rubra: "Prickly heat" due to blocked sweat ducts; erythematous papules.
  • Seborrheic dermatitis: "Cradle cap"; greasy, yellow scales on scalp/face.
  • Neonatal acne: Maternal/endogenous androgen-driven; comedones, papules, pustules.
  • Harlequin color change: Transient, benign unilateral erythema with midline demarcation.

Practice Questions: Neonatal Dermatology

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Flashcards: Neonatal Dermatology

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