Eczema herpeticum is a serious, widespread herpes simplex virus (HSV 1 or HSV 2) infection. It affects patients with atopic dermatitis or other skin conditions. In children, it typically presents as an eruption of punched-out ulcers commonly affecting sites of atopic dermatitis. It is a dermatological EMERGENCY with a fatality rate of up to 6 – 10%.
Definition of terms
| Term | Definition |
|---|---|
| Eczema herpeticum incognito | Severe, disseminated HSV infection that mimics impetigo, often delaying diagnosis in patients with atopic dermatitis and recurrent eczema herpeticum. The “incognito” presentation is caused by previously treated eczema |
- Risk factors
- Early onset or severe atopic dermatitis
- Dermatitis of the head and neck or large body surface
- Eosinophilia or high serum IgE
- Atopy (asthma and food allergies)
- History of Staphylococcus aureus infection ccus aure
- Young age
- Trauma or cosmetic procedures, e.g., lasers, skin peels, dermabrasion
- Pathophysiology
- Infection with HSV-1 or HSV-2 → replication at the site of contact in dermal keratinocytes and other epithelial sites → virus enters the cell and sensory nerve endings → retrograde transport to sensory ganglia
- Disruption of the epidermal barrier, e.g., by atopic dermatitis, impairs skin protective function → easier infection of HSV → inflammation and immune dysregulation allows for widespread infection
- Signs and symptoms
- Vesicular rash
- Blisters filled with clear yellow fluid, thick purulent material, or blood-stained
- Punched out erosions (circular, depressed, ulcerated lesions) that are uniform in appearance (monomorphic)
- Worsening, painful eczema
- Fever
- Lethargy
- Lymphadenopathy
- Differentials
- Impetigo
- Eczema vaccinatum (a rare complication of the smallpox vaccine that leads to an extensive rash and systemic illness)
- Primary varicella infection (chickenpox)
- Cellulitis
- Eczema coxsackium
- Eczema molluscum
- Pustular psoriasis
- Vasculitis
- Scabies
- Investigations
- Viral swabs for PCR, viral culture, and direct fluorescent antibody stain
- Treatment
- Oral acyclovir
- Intravenous acyclovir if unable to take orally, e.g., vomiting
- Ganciclovir for ocular involvement
- Corneal transplant for postherpetic scarring
- Complications
- Secondary infection, e.g., impetigo and cellulitis
- Scarring
- Encephalitis
- Meningitis
- Septic shock
- Multi-organ failure
- Herpetic keratitis
- Herpetic blepharoconjunctivitis
- Blindness
