Eczema Herpeticum: Recognition and Emergency Management

Overview / Definition Eczema herpeticum is a cutaneous manifestation of herpes simplex virus (HSV) infection that complicates atopic dermatitis (AD). It typically presents as widespread vesicular lesions superimposed on pre-existing eczema, leading to significant morbidity in affected patients. Epidemiology Eczema herpeticum is particularly prevalent in children, especially those under the age of 5 years. The incidence is higher among patients with moderate to severe atopic dermatitis due to the compromised skin barrier. Approximately 10-20% of children with atopic dermatitis will experience eczema herpeticum. Recurrent infection is common in patients with a history of atopic dermatitis and HSV. Pathophysiology / Mechanism The pathophysiology of eczema herpeticum involves the entry of HSV into the skin through disrupted epidermal barriers, commonly seen in atopic dermatitis. The immune response is often inadequate due to the chronic inflammation and altered immune function associated with atopic dermatitis, allowing for widespread viral replication. HSV type 1 is the most common cause, but HSV type 2 can also be implicated. The infection may lead to systemic symptoms such as fever and lymphadenopathy. Clinical Presentation Patients with eczema herpeticum typically present with: Clusters of vesicles or pustules that rapidly evolve into erosions and crusts. Lesions that are painful and may be accompanied by fever, malaise, and lymphadenopathy. Worsening of the underlying eczema, often with increased pruritus. It is important to differentiate eczema herpeticum from other vesicular lesions, as misdiagnosis can lead to inappropriate management. Diagnosis / Workup The diagnosis of eczema herpeticum is primarily clinical, but laboratory confirmation can be obtained through: Polymerase chain reaction (PCR) testing of fluid from vesicles for HSV. Direct fluorescent antibody (DFA) testing, although less sensitive than PCR. Viral culture, which can take longer to yield results