Overview
Definition:
Eczema herpeticum (EH) is a severe, disseminated herpes simplex virus (HSV) infection that occurs in individuals with compromised skin barrier function, most commonly atopic dermatitis.
Epidemiology:
It can occur at any age but is more common in infants and young children
Incidence is difficult to quantify precisely, but it is a recognized complication of severe atopic dermatitis
Neonatal herpes is a distinct but related entity.
Clinical Significance:
EH is a medical emergency due to its potential for rapid progression, systemic dissemination, and life-threatening complications including encephalitis, sepsis, and disseminated intravascular coagulation (DIC)
Prompt diagnosis and treatment are crucial for favorable outcomes.
Clinical Presentation
Symptoms:
Sudden onset of fever
Malaise and lethargy
Painful, itchy, vesicular rash that can rapidly evolve into pustules and erosions
Worsening of underlying eczema
Irritability in infants
Signs of systemic illness.
Signs:
Widespread, umbilicated vesicles and pustules, often superimposed on eczematous skin lesions
Lesions are typically uniform in stage within a given area
Regional lymphadenopathy
Potential for mucocutaneous involvement (eyes, mouth, genitals)
Signs of dehydration, sepsis, or organ involvement (e.g., neurological deficits).
Diagnostic Criteria:
No universally agreed-upon formal criteria exist, but a diagnosis is strongly suspected in a patient with underlying eczema who develops a sudden onset of fever and widespread vesicular, pustular, and erosive lesions
Viral confirmation is essential.
Diagnostic Approach
History Taking:
Detailed history of underlying skin condition (onset, severity, treatments)
Recent exposure to individuals with herpes simplex infection (herpes labialis, genital herpes)
Fever, malaise, and progression of skin lesions
Any eye involvement (redness, photophobia) is a critical red flag.
Physical Examination:
Thorough skin examination to assess the distribution, morphology (vesicular, pustular, erosive), and stage of lesions
Assess for signs of systemic illness: vital signs, hydration status, neurological examination, ocular examination.
Investigations:
Viral isolation via viral culture (Tzanck smear with Giemsa stain may show multinucleated giant cells and intranuclear inclusions, but is less sensitive than PCR)
Polymerase chain reaction (PCR) on vesicle fluid or biopsy is the gold standard for detecting HSV DNA and identifying HSV type (HSV-1 or HSV-2)
Serology is generally not useful for acute diagnosis but may help in identifying primary HSV infection in some cases
Blood tests may include complete blood count (CBC) with differential, electrolytes, and liver function tests to assess for systemic involvement.
Differential Diagnosis:
Impetigo (bacterial infection, typically crusted lesions)
Varicella (chickenpox, lesions are in different stages and typically distributed on trunk)
Vaccinia (generalized vaccinia if recently vaccinated)
Other forms of viral exanthems
Candidiasis (intertriginous areas, satellite lesions).
Management
Initial Management:
Hospitalization is often required, especially in severe cases, infants, or immunocompromised individuals
Prompt initiation of intravenous antiviral therapy
Fluid and electrolyte management
Pain control.
Medical Management:
Antiviral therapy is the cornerstone
Intravenous acyclovir is the preferred agent
Dosage for neonates: 20 mg/kg per dose given every 8 hours
Dosage for older children: 10-15 mg/kg per dose given every 8 hours
Duration of treatment is typically 7-14 days, or at least 7 days after lesions have crusted over and patient is afebrile
Oral antiviral agents (valacyclovir, famciclovir) may be used for milder cases or as step-down therapy in select patients, guided by clinical response and local resistance patterns.
Supportive Care:
Aggressive skin care to prevent secondary bacterial superinfection (e.g., dilute bleach baths may be considered in some cases of underlying eczema but should be used cautiously and under medical supervision)
Wound care for erosions
Nutritional support
Close monitoring for signs of complications
Isolation precautions if in a hospital setting to prevent transmission.
Management Of Underlying Eczema:
Management of the underlying atopic dermatitis is critical for long-term prevention
This includes regular emollients, topical corticosteroids as needed, and avoidance of triggers.
Complications
Early Complications:
Secondary bacterial superinfection of skin lesions (e.g., Staphylococcus aureus, Streptococcus pyogenes)
Dehydration
Electrolyte imbalances
Sepsis
Disseminated intravascular coagulation (DIC)
Pneumonitis.
Late Complications:
Herpetic encephalitis (can lead to permanent neurological sequelae)
Ocular involvement leading to corneal scarring and vision loss
Scarring of the skin
Recurrent episodes of EH.
Prevention Strategies:
Aggressive management of underlying atopic dermatitis
Patient and parental education on recognizing early signs of EH
Prophylactic antiviral therapy may be considered in select high-risk individuals with severe, recurrent eczema, but this is not standard practice and requires careful risk-benefit assessment.
Prognosis
Factors Affecting Prognosis:
Promptness of diagnosis and initiation of antiviral therapy
Severity of systemic involvement
Age of the patient (infants and neonates have higher mortality)
Underlying immune status.
Outcomes:
With prompt and appropriate treatment, most children recover fully
However, severe cases can be associated with significant morbidity and mortality
Neurological and ocular complications can lead to long-term disability.
Follow Up:
Close follow-up is necessary to ensure complete resolution of lesions and to monitor for any long-term sequelae
Management of the underlying eczema should be optimized
Education on recognizing and managing future recurrences is vital.
Key Points
Exam Focus:
EH is a viral dissemination in compromised skin, usually atopic dermatitis
IV acyclovir is first-line
Think sepsis, encephalitis, DIC as major complications
Differentiate from impetigo and varicella.
Clinical Pearls:
Always consider EH in a child with eczema presenting with fever and widespread vesicles, especially if lesions are uniform in stage
Ocular involvement is a critical ophthalmological emergency
Prompt IV acyclovir is paramount.
Common Mistakes:
Delaying antiviral therapy due to diagnostic uncertainty
Underestimating the severity and potential for systemic complications
Inadequate management of the underlying eczema, leading to recurrence.