Pediatric Dermatology Basics

Neonatal Skin - Fresh & Fragile

• Physiological Findings:
  • Vernix Caseosa: Waxy, white, protective coating.
  • Lanugo: Fine, soft hair; sheds weeks 1-2.
  • Acrocyanosis: Peripheral cyanosis; resolves with warming.
  • Cutis Marmorata: Mottled vascular pattern; cold stress.
  • Physiological Desquamation: Peeling, esp. post-term.
• Benign Transient Rashes:
  • Erythema Toxicum Neonatorum (ETN): "Flea-bitten" rash; macules, papules, pustules on erythematous base. Appears day 2-5, spares palms/soles.

    ⭐ ETN smear shows numerous eosinophils.

  • Transient Neonatal Pustular Melanosis (TNPM): Pustules at birth → collarettes of scale → pigmented macules. Neutrophils on smear.
  • Milia: Tiny white keratin cysts; face (nose, chin).
  • Miliaria: Sweat duct obstruction.
    • Miliaria Crystallina: Superficial clear vesicles.
    • Miliaria Rubra (Prickly Heat): Erythematous papules/pustules.
  • Sebaceous Gland Hyperplasia: Yellowish papules on nose/cheeks; maternal androgens.

Birthmarks - Unique Stamps

• Vascular Birthmarks:
  • Nevus Simplex (Salmon Patch/Stork Bite): Common, flat, pink patches (nape, eyelids, glabella). Usually fade by 1-2 years.
  • Port-Wine Stain (Nevus Flammeus): Dark red/purple vascular malformation. Permanent, grows with child. If V1 ophthalmic trigeminal distribution, suspect Sturge-Weber syndrome.
  • Infantile Hemangioma (Strawberry Nevus): Bright red, raised. Proliferate in first months, then involute. Propranolol for complicated cases (e.g., visual obstruction).
• Pigmented Birthmarks:
  • Mongolian Spot (Congenital Dermal Melanocytosis): Blue-grey macules, lumbosacral area. Common in Asian/darker skin. Fade in childhood.
  • Café-au-Lait Macules (CALMs): Light brown, flat. Multiple (>6 lesions, >5mm prepubertal, >15mm postpubertal) suggest Neurofibromatosis Type 1 (NF1).
  • Congenital Melanocytic Nevus (CMN): Brown/black. Risk of melanoma ↑ with size (especially giant CMNs >20cm).
• Epidermal Nevi:
  • Nevus Sebaceous (of Jadassohn): Yellowish, waxy, hairless plaque (often scalp). Risk of secondary benign/malignant neoplasms (e.g., BCC) in adulthood.

⭐ Port-wine stain in the V1 trigeminal nerve distribution is highly suggestive of Sturge-Weber syndrome, which can involve ipsilateral glaucoma and leptomeningeal angiomas causing seizures and neurological deficits.

Pediatric Infections - Tiny Invaders

• Impetigo: S. aureus, Group A Strep. Honey-colored crusts (non-bullous); flaccid bullae (bullous). Topical/oral antibiotics.
• Molluscum Contagiosum: Poxvirus. Flesh-colored, umbilicated papules. Spontaneous resolution common.
• Scabies: Sarcoptes scabiei. Intense nocturnal pruritus. Burrows (interdigital, wrists, axillae). Permethrin 5% cream. Treat contacts.
• Tinea Capitis: Dermatophytes. Scalp scaling, alopecia, black dots, kerion. Oral griseofulvin.

  ⭐ Wood's lamp: Microsporum spp. fluoresce green.

• Viral Warts (Verrucae): HPV. Common (vulgaris), flat (plana), plantar. Salicylic acid, cryotherapy.
• Hand-Foot-Mouth Disease (HFMD): Coxsackie A. Oral, hand, foot vesicles. Supportive care.

Inflammatory Dermatoses - Itchy Issues

• Atopic Dermatitis (AD): "Itch that rashes"; chronic, relapsing.
  • Infants: Face, extensors. Spares diaper area.
  • Children: Flexures.
  • Associated with atopic march. Filaggrin mutations.
  • Tx: Emollients, topical steroids, TCIs.
• Seborrheic Dermatitis (SD): Greasy scales, erythema.
  • Infants: "Cradle cap" (scalp), face, diaper area.
  • Malassezia implicated.
  • Tx: Antifungal shampoos, mild topical steroids.
• Psoriasis: Well-demarcated silvery plaques.
  • Extensors, scalp, nails. Auspitz sign, Koebner.
  • Guttate psoriasis: Post-streptococcal.
• Contact Dermatitis:
  • Irritant (ICD): Direct injury (e.g., diapers, soaps).
  • Allergic (ACD): Type IV hypersensitivity (e.g., nickel). Patch test.

⭐ Infantile atopic dermatitis typically affects the face (cheeks, chin, forehead) and extensor surfaces, often sparing the diaper area.

High‑Yield Points - ⚡ Biggest Takeaways

• Neonatal acne (first weeks, resolves) vs. Infantile acne (3-6 months, may scar, more persistent).
• Erythema toxicum neonatorum: Benign "flea-bitten" rash with eosinophils, resolves in days.
• Mongolian spots: Common benign blue-grey lumbosacral macules, typically fade during childhood.
• Infantile hemangiomas: Characteristically proliferate then involute; propranolol for problematic lesions.
• Atopic dermatitis: Key feature is intense pruritus; distribution varies with age (infant vs. child).
• Diaper dermatitis: Irritant contact is most common; Candidal infection presents with satellite pustules.