Neonatal skin lesions

Benign Transient Neonatal Dermatoses

Erythema Toxicum Neonatorum (ETN)

• Onset: Day 1–3 of life (peaks at 24–48 hours; rare in premature infants).
• Benign, self-limited neonatal rash.
• Clinical Features: Blotchy, erythematous macules with central pale papules or pustules (“flea-bitten” appearance); distributed on trunk and proximal extremities; spares palms and soles.
• Diagnostic Workup: Clinical diagnosis. If pustule scraped: Wright-Giemsa stain shows numerous eosinophils.
• Management: Reassurance only; resolves spontaneously within 1–2 weeks.

Transient Neonatal Pustular Melanosis (TNPM)

• Epidemiology: Common in full-term infants of African descent.
• Onset: Present at birth.
• Clinical Features (3 sequential stages):
  1. Small, non-erythematous pustules/vesicles.
  2. Ruptured pustules with a collarette of fine scale.
  3. Pinpoint hyperpigmented macules (can persist for months).
  • May involve palms and soles.
• Diagnostic Workup: Wright-Giemsa stain shows numerous neutrophils (sterile culture).
• Management: Reassurance; no treatment required.

Milia & Epstein Pearls

• Pathophysiology: Keratin-filled epithelial cysts.
• Clinical Features: 1–2 mm pearly white/yellow papules on the nose, cheeks, and forehead. Epstein pearls are identical lesions located on the hard palate/gingiva.
• Management: Reassurance; resolves spontaneously within the first few weeks to months.

Miliaria (Heat Rash)

• Pathophysiology: Occlusion of eccrine sweat ducts due to overheating/bundling.
• Subtypes:
  • Miliaria Crystallina: Superficial clear vesicles without inflammation (resembles dew drops).
  • Miliaria Rubra: Pruritic, erythematous papules/pustules in intertriginous/occluded areas.
• Management: Cool environment, light clothing, avoid occlusive dressings.

Neonatal Cephalic Pustulosis (Neonatal Acne)

• Onset: Typically at 2–3 weeks of life (distinguishes from ETN/TNPM).
• Pathophysiology: Inflammatory reaction to Malassezia colonization; maternal androgens.
• Clinical Features: Inflammatory papules and pustules on cheeks and nose; lacks true comedones.
• Management: Gentle cleansing w/ soap and water. If severe/refractory: topical 2% ketoconazole or 1% hydrocortisone.

Congenital Dermal Melanocytosis (Mongolian Spot)

• Pathophysiology: Failure of embryologic migration of melanocytes from the neural crest to the epidermis; arrested melanocytes reside deep within the dermis (Tyndall effect causes blue-gray appearance).
• Epidemiology: Extremely common in neonates of Asian, African, Hispanic, and Native American descent (80–90%).
• Clinical Features:
  • Flat, poorly demarcated, blue-gray or slate-brown macules and patches.
  • Location: Most commonly the lumbosacral region and buttocks; occasionally on shoulders, back, or posterior thighs.
  • Normal skin texture: No induration, tenderness, or edema.
• Diagnosis: Purely clinical.
• Differential Diagnosis:
  • Non-accidental trauma / Child abuse (Bruising): Bruises are tender, have overlying swelling, change color over days (red/purple → yellow/green), and occur in atypical locations. Dermal melanocytosis remains stable, non-tender, and uniform in color.
  • Nevus of Ota: Dermal melanocytosis along the ophthalmic (V1) and maxillary (V2) divisions of CN V; involves sclera and periorbital skin.
  • Nevus of Ito: Dermal melanocytosis in the supraclavicular/deltoid and scapular distribution.
• Management:
  • Reassurance: Benign condition with no malignant potential. c
  • Documentation: Must be meticulously documented in the neonatal medical record at birth to prevent future false suspicion or allegations of physical child abuse.
  • Course: Gradually fades over the first few years of life; usually resolves completely by puberty.

Congenital Melanocytic Nevus (CMN)

• Pathophysiology: Benign proliferation of neural crest-derived melanocytes present at birth.
• Clinical Features:
  • Hyperpigmented, well-circumscribed macule, patch, or plaque.
  • Frequently develops overlying dark, coarse terminal hair (hypertrichosis).
  • Surface may become verrucous, rugose, or pebbly with age.
• Size Stratification (Projected Adult Size - PAS):
  • Small: < 1.5 cm.
  • Medium: 1.5 – 19.9 cm.
  • Large / Giant: ≥ 20 cm (or > 5% total body surface area; classic “bathing trunk” or “garment” distribution).
• Complications & High-Yield Associations:
  • Malignant Melanoma: Risk correlates directly with size. Giant CMN carries a 2–5% lifetime risk of malignant melanoma (highest in the first decade of life). Small/medium lesions carry minimal/negligible risk.
  • Neurocutaneous Melanocytosis (NCM): Melanocyte deposition in the leptomeninges and brain parenchyma.
    • Risk Factors: Giant CMN (especially on axial/posterior trunk or head/neck) or ≥ 3 satellite nevi.
    • Complications: Obstructive hydrocephalus, increased ICP, seizures, neurologic deficits, and primary leptomeningeal melanoma.
• Diagnosis & Workup:
  • Screening: Brain and Spine MRI w/ contrast (ideally performed before 4–6 months of age, prior to complete normal brain myelination which obscures leptomeningeal lesions) for infants with giant CMN or high-risk features (multiple satellite nevi, axial location).
  • Regular dermatologic surveillance w/ serial photography and dermoscopy.
• Management:
  • Small/Medium: Serial observation and routine dermatologic monitoring.
  • Giant/Large: Surgical excision (staged excision or tissue expansion) considered for cosmesis or atypical changes. Note: Surgical removal reduces but does not entirely eliminate the risk of melanoma, as malignant transformation can occur in deeper subcutaneous tissue or the central nervous system.