👶 Chapter 47: Congenital Cutaneous Lesions and Infantile Rashes

Nelson's Pediatric Symptom-Based Diagnosis | Erythema Toxicum · Transient Neonatal Pustular Melanosis · Miliaria · Neonatal Acne · Seborrheic Dermatitis · Diaper Dermatitis · Hemangiomas · Capillary Malformations · Infantile Hemangioma · PHACE/PELVIS Syndromes · Neurocutaneous Markers

🔍 Congenital Cutaneous Lesions & Infantile Rashes: Key Concepts

📊 Papules & Pustules
Erythema toxicum: blotchy red macules with central papule/pustule, eosinophils. Transient neonatal pustular melanosis: pustules without erythema, hyperpigmented macules. Miliaria: heat-induced vesicles/papules.
🩷 Vascular Birthmarks
Infantile hemangioma: proliferative phase (0-6m), involution (1-9y). PHACE syndrome: segmental facial hemangioma + brain/cardiac anomalies. Capillary malformation (port-wine stain): Sturge-Weber if V1 distribution.
🧴 Seborrheic Dermatitis
Yellow, greasy scale on scalp (cradle cap), face, intertriginous areas. Malassezia yeast. Treat with low-potency steroids, antifungals, shampoos.
🧷 Diaper Dermatitis
Irritant, candidal (satellite lesions), seborrheic, allergic contact. Treat with barrier creams, antifungals, frequent changes. Severe or persistent → consider Langerhans cell histiocytosis.
⚠️ Red Flags (Neurocutaneous)
Ash leaf spots (tuberous sclerosis), >6 café-au-lait spots (NF1), capillary malformation V1 (Sturge-Weber), midline hemangioma/hair collar (spinal dysraphism), giant melanocytic nevus (neurocutaneous melanosis).
🩺 Other Lesions
Congenital melanocytic nevus: risk of melanoma (giant >2%). Juvenile xanthogranuloma: yellow nodules, may have ocular involvement. Subcutaneous fat necrosis: monitor for hypercalcemia.

💡 Key takeaway: Most neonatal rashes are benign (erythema toxicum, miliaria, transient pustular melanosis). Identify red flags: segmental hemangiomas (PHACE/PELVIS), midline lesions (spinal dysraphism), and neurocutaneous markers (ash leaf spots, café-au-lait, capillary malformations).

🩺 Clinical Approach to Congenital and Infantile Cutaneous Lesions

🔹 Step 1: Assess morphology and timing
• Present at birth: congenital melanocytic nevus, capillary malformation, dermal melanocytosis (Mongolian spot), aplasia cutis.
• First few days: erythema toxicum (day 2-4), transient neonatal pustular melanosis (present at birth), miliaria.
• First weeks: seborrheic dermatitis (2-4wk), neonatal acne (3-4wk), hemangiomas become visible.
• Persistent beyond infancy: suspect systemic disease.
🔹 Step 2: Identify vascular lesions (hemangioma vs malformation)
• Infantile hemangioma: appears after birth, proliferates (0-6m), then involutes. Risk: PHACE (face), PELVIS/SACRAL (lumbosacral).
• Capillary malformation (port-wine stain): present at birth, grows proportionally, darkens. If V1 distribution → Sturge-Weber (eye/brain imaging).
• Nevus simplex (salmon patch): glabella, nape, fades by age 2.
• Kasabach-Merritt: consumptive coagulopathy with kaposiform hemangioendothelioma (not infantile hemangioma).
🔹 Step 3: Recognize neurocutaneous red flags
• Ash leaf macule (hypopigmented) → tuberous sclerosis → Wood lamp, brain MRI.
• >6 café-au-lait spots (>0.5cm prepubertal) → neurofibromatosis type 1.
• Midline lumbosacral hemangioma, dimple, hair tuft, or lipoma → spinal dysraphism (tethered cord).
• Giant congenital melanocytic nevus (>20cm adult size) → neurocutaneous melanosis (MRI brain/spine).
🔹 Step 4: Diaper dermatitis differential
• Irritant: convex surfaces, spares creases. Treat with barrier, frequent changes.
• Candidal: bright red, satellite pustules, creases involved, often with thrush. Nystatin/clotrimazole.
• Seborrheic: salmon-colored patches, yellow scale, also on scalp/face.
• Langerhans cell histiocytosis: erosive, crusted, purpuric, refractory to standard treatment → biopsy.
🔹 Step 5: Monitor for complications
• Subcutaneous fat necrosis: indurated plaques after perinatal stress → check serum calcium weekly for hypercalcemia (delayed onset).
• Giant hemangiomas → high-output heart failure, hypothyroidism (type 3 deiodinase).
• Urticaria pigmentosa (mastocytosis): Darier sign (urtication with stroking), risk of systemic symptoms with histamine release.