Overview
Eczema Herpeticum
Topic Overview
Summary
Eczema herpeticum is a disseminated herpes simplex virus (HSV) infection occurring in patients with pre-existing atopic dermatitis or other skin barrier disorders. It is a dermatological emergency characterised by widespread vesicles and punched-out erosions on eczematous skin, often with systemic symptoms. Without treatment, it can cause severe complications including keratitis, meningitis, and death. Treatment is urgent IV aciclovir for severe cases or oral aciclovir/valaciclovir for mild cases.
Key Facts
- Cause: HSV-1 (most common) or HSV-2 infection on disrupted skin
- Risk group: Atopic dermatitis (especially severe/uncontrolled)
- Presentation: Vesicles, punched-out erosions, fever, malaise
- Emergency: Can cause keratitis, visceral dissemination, death
- Treatment: IV aciclovir (severe) or oral aciclovir/valaciclovir (mild)
Clinical Pearls
"Punched-out erosions" in a patient with eczema = eczema herpeticum until proven otherwise
Always examine the eyes — herpetic keratitis can cause blindness
Do NOT use topical steroids alone — will worsen infection
Why This Matters Clinically
Eczema herpeticum is easily missed if mistaken for infected eczema. Delayed treatment leads to serious complications including vision loss and death.
Visual Summary
Visual assets to be added:
- Eczema herpeticum clinical photos
- Punched-out erosions close-up
- Comparison with bacterial superinfection
- Management algorithm
Epidemiology
Incidence
- Uncommon but important
- 3% of hospitalised atopic dermatitis patients
Demographics
- Children and young adults most common
- Any age with atopic dermatitis
- Rare in adults without skin disease
Risk Factors
| Factor | Notes |
|---|---|
| Atopic dermatitis | Major risk factor (especially severe) |
| Other skin barrier disorders | Darier disease, pemphigus, burns |
| Immunocompromise | HIV, chemotherapy |
| Topical calcineurin inhibitors | Possible association |
| Early onset severe eczema |
Pathophysiology
Mechanism
- HSV (usually HSV-1) infects disrupted skin barrier
- Virus spreads across eczematous areas
- Widespread vesicle formation
- Potential systemic dissemination
Why Atopic Dermatitis Predisposes
- Impaired skin barrier (filaggrin deficiency)
- Reduced antimicrobial peptides
- Th2 immune skewing
- Often colonised with Staphylococcus aureus
HSV Types
- HSV-1: Most common cause
- HSV-2: Less common; genital herpes dissemination
Clinical Presentation
Symptoms
Signs
Distribution
Distinguishing from Bacterial Superinfection
| Feature | Eczema Herpeticum | Bacterial Infection |
|---|---|---|
| Lesions | Punched-out erosions, vesicles | Pustules, crusting |
| Edges | Clean, round | Irregular |
| Vesicles | Monomorphic | Absent |
| Pain | Significant | Variable |
| Systemic symptoms | Common | May be present |
Red Flags
| Finding | Significance |
|---|---|
| Eye involvement | Urgent ophthalmology — risk of keratitis |
| Widespread disease | IV aciclovir needed |
| Immunocompromise | Higher risk of dissemination |
| Systemic illness | Visceral involvement possible |
Acute eruption of painful vesicles/erosions
Common presentation.
Fever, malaise
Common presentation.
Rapid spread over 7-10 days
Common presentation.
Pain out of proportion to appearance
Common presentation.
Clinical Examination
Skin
- Monomorphic vesicles on erythematous base
- Punched-out erosions (2-3mm)
- Haemorrhagic crusting
- Distribution over eczematous areas
Eyes — ESSENTIAL
- Check for conjunctivitis
- Dendritic ulcer (requires slit lamp)
- Periorbital involvement
Lymph Nodes
- Regional lymphadenopathy
General
- Fever
- Signs of sepsis (if severe)
Investigations
Viral Testing
| Test | Notes |
|---|---|
| Viral swab (PCR) | Gold standard; from vesicle base |
| Viral culture | Less sensitive than PCR |
| Tzanck smear | Multinucleated giant cells — rapid but non-specific |
Blood Tests
| Test | Purpose |
|---|---|
| FBC | WCC may be elevated or low |
| U&E, LFTs | If systemically unwell |
| Blood cultures | If septic |
Eye Examination
- Slit lamp by ophthalmology if periorbital or eye symptoms
Classification & Staging
By Severity
| Severity | Features |
|---|---|
| Localised/mild | Limited area, systemically well |
| Moderate | Widespread but stable |
| Severe | Systemic symptoms, extensive, immunocompromised |
Management
General Principles
- High clinical suspicion — treat empirically
- Do NOT delay for virology results
- Stop topical calcineurin inhibitors
- Continue emollients
Antiviral Therapy
Mild/Localised (Systemically Well):
| Agent | Dose | Duration |
|---|---|---|
| Oral aciclovir | 400-800mg 5x/day | 10-14 days |
| Or valaciclovir | 1g TDS | 10-14 days |
Moderate to Severe (Systemic Symptoms, Widespread, Immunocompromised):
| Agent | Dose | Duration |
|---|---|---|
| IV aciclovir | 5-10mg/kg TDS | Until improving, then oral |
Ocular Involvement
- Urgent ophthalmology referral
- Topical antivirals (aciclovir ointment, ganciclovir gel)
- May need systemic antivirals
Bacterial Superinfection
- Common — add antibiotics if suspected
- Flucloxacillin or co-amoxiclav
Supportive Care
- Analgesia
- Wound care
- Emollients
- IV fluids if dehydrated
Eczema Management
- Continue emollients
- May resume topical steroids once infection controlled
- Avoid calcineurin inhibitors during acute infection
Complications
Local
- Scarring
- Secondary bacterial infection
- Post-herpetic hypopigmentation
Ocular
- Herpetic keratitis
- Corneal scarring
- Blindness
Systemic (Rare)
- Viraemia
- Meningitis/encephalitis
- Hepatitis
- Death (especially immunocompromised)
Prognosis & Outcomes
Prognosis
- Excellent with prompt treatment
- Resolution in 2-6 weeks
- Recurrence possible (20-30%)
Mortality
- Rare with treatment
- Higher in immunocompromised without treatment
Evidence & Guidelines
Key Guidelines
- BAD Guidelines on Atopic Eczema
- NICE CKS on Eczema Herpeticum
Key Evidence
- Early antiviral treatment reduces complications
- IV aciclovir for severe disease
Patient & Family Information
What is Eczema Herpeticum?
Eczema herpeticum is a skin infection caused by the cold sore virus (herpes simplex) spreading across eczema-affected skin. It is serious and needs urgent treatment.
Symptoms
- Painful blisters that spread quickly
- Small round sores with clean edges
- Fever and feeling unwell
Treatment
- Antiviral tablets or medicine through a drip
- Quick treatment prevents complications
When to Seek Help
- New spreading blisters on eczema
- Feeling feverish or unwell
- Any eye symptoms
Resources
References
Key Reviews
- Wollenberg A, et al. Eczema herpeticum. Chem Immunol Allergy. 2012;96:116-123. PMID: 22433381
- Leung DY. Why is eczema herpeticum unexpectedly rare? Antiviral Res. 2013;98(2):153-157. PMID: 23439082
Guidelines
- NICE CKS. Eczema - atopic. 2021.
- Wollenberg A, et al. European guidelines for treatment of atopic eczema. J Eur Acad Dermatol Venereol. 2018;32(5):657-682. PMID: 29676534