Skin biology, genodermatoses and pediatric patterns
Neonatal and infant skin
Erythema toxicum (blotchy erythema with eosinophil-rich pustules, early neonatal life, self-limiting), miliaria (sweat duct obstruction) and neonatal cephalic pustulosis are benign , recognise them so antibiotics are avoided. Nappy rash: irritant dermatitis spares the flexures, whereas candidal dermatitis involves flexures with satellite pustules; seborrhoeic dermatitis is a third pattern.
Inherited disorders
Neurofibromatosis type 1 can involve six or more café-au-lait macules over 5 mm (prepubertal), axillary or inguinal freckling, neurofibromas, Lisch nodules, optic glioma. Tuberous sclerosis: ash-leaf macules, facial angiofibromas, shagreen patch, seizures. Sturge-Weber: facial port-wine stain involving the forehead or upper eyelid with neurological and ocular risk. Ichthyosis and epidermolysis bullosa need multidisciplinary care.
Vascular anomalies
Infantile haemangioma appears after birth, proliferates, then involutes; oral propranolol is indicated for problematic lesions (ulceration, visual axis, airway, large segmental). Segmental facial haemangioma should prompt consideration of PHACE syndrome. Port-wine stains commonly persist and respond to pulsed dye laser.
Common paediatric dermatoses
Atopic dermatitis, molluscum contagiosum, viral warts, tinea capitis, hand-foot-and-mouth disease and drug eruptions are frequent. Mastocytosis shows a positive Darier sign on rubbing.
Traps
- Missing a segmental haemangioma syndrome.
- Treating tinea capitis with topical therapy alone.
- Attributing blistering in a newborn to infection when a genodermatosis is possible.
- Overlooking safeguarding when lesions do not fit the history.
Rule of thumb
In a child, a "birthmark" plus one syndrome feature means look carefully for a second and third before reassuring the family.
Skin structure and inheritance
The epidermal barrier depends on differentiated keratinocytes, cornified-envelope components and extracellular lipids. Keratin intermediate filaments, desmosomes, hemidesmosomes and anchoring structures act at different anatomical levels. A defect in a keratin pair is not the same mechanism as loss of a dermal anchoring fibril. Linking the molecular component with the plane of fragility helps interpret inherited blistering disorders and their distinction from acquired autoimmunity. Filaggrin-related barrier dysfunction can contribute to an ichthyosis and atopic phenotype, while type VII collagen is central to the anchoring-fibril system affected in dystrophic epidermolysis bullosa.
Genetic evaluation combines the phenotype, family history, inheritance pattern and appropriate molecular assessment. A single birthmark is not proof of a complete syndrome. Conversely, a reassuring surface description should not obscure neurological, ocular or other systemic risk in a compatible pattern. Childhood vascular anomalies differ in natural history: an infantile hemangioma has a characteristic postnatal growth phase, while a capillary malformation is a different entity. Observation versus active treatment depends on functional risk, ulceration, location and the actual diagnosis. A lesion threatening vision or airway function warrants prompt specialist assessment, not a copied unsupervised beta-blocker regimen. Explain uncertainty and follow-up needs to caregivers without implying that every inherited condition follows an identical course.