Eczema Herpeticum

Five days before this 1-year-old girl was brought to her doctor's office, a rash had developed on her left shoulder and the left side of her chest. The abrupt onset of a high fever (temperature, 41°C [105.8°F]) and irritability accompanied the outbreak of the rash. The child had a history of asthma and eczema.

Drs Alexander K. C. Leung and Helen Y. H. Cho of Calgary, Alberta, made the diagnosis of eczema herpeticum, a widespread cutaneous herpes simplex virus infection that develops in eczematous skin. The rash begins as a cluster of umbilicated vesicles over eczematous skin and progresses over 7 to 10 days as new crops develop.

Typically, the vesicles form pustules that rupture and crust over the course of a few days. The lesions initially are isolated but can become grouped and may erupt on adjoining areas of normal skin. They may hemorrhage and can become secondarily infected with bacteria. Systemic reactions vary, but temperatures of 39.5°C to 40.5°C (103.1°F to 104.9°F) are not uncommon in patients with eczema herpeticum.

Drs Leung and Cho report that the eczema herpeticum rash may simulate chickenpox lesions. However, the slower evolution of the lesions, the tendency for some of the lesions to hemorrhage, the primary localization to eczematous areas, and the persistence of fever and systemic symptoms for more than a few days help distinguish eczema herpeticum from chickenpox.

Eczema herpeticum usually responds to oral or intravenous acyclovir. Acyclovir enters the affected cells, where it is activated selectively by herpes simplex virus thymidine kinase, which, in turn, specifically inhibits replication of the virus. The rash in this patient disappeared after 5 days of treatment with oral acyclovir.