Atopic dermatitis/eczema

Overview

•Pruritus - cardinal symptom; intense, nocturnal, worse with heat/sweating

•Xerosis - dry, rough skin reflecting barrier failure

•Lichenification - thickened leathery skin from chronic scratching

•Vesicles - in acute flares or pompholyx subtype

•Onset - typically early childhood; 90% present before age 5

Investigations

•Clinical diagnosis - based on UK Working Party criteria (itch + 3 of: onset <2 yrs, flexural involvement, dry skin, personal/family atopic history, visible flexural eczema)

•Skin swab - bacterial culture if secondary infection suspected (Staph. aureus most common)

•Viral swab (HSV PCR) - urgent if eczema herpeticum suspected

•Patch testing - specialist setting; to identify allergic contact sensitisation

Management

•All patients: emollients as soap substitute; avoid aqueous cream (contains sodium lauryl sulphate); identify and avoid triggers

🥇 First-line

•emollients (e.g. Diprobase, Epaderm) - liberal and frequent application; cornerstone of all treatment

•First-line flare (face/flexures): hydrocortisone 1% - mild topical corticosteroid; thin skin absorbs more

•First-line flare (trunk/limbs): clobetasone butyrate 0.05% (Eumovate) - moderate potency; avoid on face

🥈 Second-line

•betamethasone valerate 0.1% (Betnovate) - potent; trunk/limbs only, never face; specialist guidance in children

•Second-line (face/flexures, steroid-sparing): tacrolimus 0.03% (children 2-15 yrs) or 0.1% (adults); pimecrolimus 1% - no skin-thinning effect

🥉 Third-line

•oral ciclosporin - severe refractory eczema in adults; monitor renal function and BP

•Third-line (biological): dupilumab (anti-IL-4/IL-13) - moderate-to-severe, failed systemic immunosuppression; NICE-approved; SC every 2 weeks

Complications

•Eczema herpeticum - HSV superinfection; medical emergency; IV aciclovir

•Topical corticosteroid side effects - skin atrophy, striae, telangiectasia, adrenal suppression (children with widespread potent steroid use)

•Sleep disturbance - from nocturnal pruritus; significant quality of life impact

•Psychological comorbidity - anxiety and depression more prevalent in moderate-to-severe eczema

Pompholyx (dyshidrotic eczema)

•Intensely itchy, deep-seated vesicles on palms, lateral fingers, and soles

•Triggered by heat, sweating, and humidity - worse in hot/humid environments

•Vesicles 1-2 mm, clear, tapioca-like; followed by scaling and fissuring

•More common in young adults; females > males

🎯

Pompholyx vs atopic eczema: pompholyx = vesicular, palms/soles, triggered by sweat/heat. Atopic eczema = dry/eczematous patches, flexural, onset in early childhood. Pompholyx does NOT follow a relapsing-remitting cycle in the classic atopic sense.

Eczema herpeticum

•HSV-1 superinfection of eczematous skin - medical emergency

•Widespread monomorphic punched-out erosions/vesicles, typically face and neck

•Systemic features: fever, lymphadenopathy, reduced oral intake, irritability

•Management: urgent hospital admission + IV aciclovir - do NOT give antibiotics alone or delay

🚨

A child with known eczema who develops widespread blistering + fever + systemic upset = eczema herpeticum. Refer urgently to hospital. Do not treat with topical steroids, antifungals, or antibiotics alone.

Infected eczema

•Most commonly Staphylococcus aureus - weeping, crusting, pustules

•Oral: flucloxacillin; if penicillin-allergic and pregnant: erythromycin; if penicillin-allergic (non-pregnant): cefalexin

•Localised infection: topical fusidic acid may be sufficient

•Refer urgently if suspected eczema herpeticum - do not give antibiotics alone

Pregnancy-related dermatoses

Pregnancy dermatoses - key distinguishing features

Feature	Atopic eruption of pregnancy	Pemphigoid gestationis	Polymorphic eruption of pregnancy (PEP)
Incidence	1 in 300 - most common dermatosis in pregnancy	1 in 1700 to 1 in 50,000 - rare	Common
Trimester	2nd or 3rd trimester	2nd or 3rd trimester	3rd trimester / post-partum
Morphology	Itchy erythematous papules; excoriated nodules	Urticarial plaques progressing to tense vesicles/bullae	Urticarial papules and plaques
Distribution	Face, neck, chest, extensor limbs	Periumbilical - pathognomonic starting point	Within striae on abdomen; spares periumbilicus
Safety	Benign; no adverse fetal effects	Serious autoimmune disorder - autoantibodies to BP180	Benign

🎯

Periumbilical blistering in pregnancy = pemphigoid gestationis until proven otherwise. PEP spares the periumbilicus. Atopic eruption of pregnancy shows excoriated papules/nodules on face and neck.