Pediatric Dermatology

Herpes Zoster in Children

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Herpes zoster usually is diagnosed based on its clinical presentation. Human herpesvirus 1 or 2 also may present with similar lesions and should be included in the differential diagnosis. To confirm a clinical diagnosis, additional testing may be done. A Tzanck smear historically has been the least expensive and most rapid test. Scrapings can be taken from the base of a vesicle, stained, and examined for multinucleated giant cells; however, a Tzanck smear cannot help in distinguishing herpes simplex virus from VZV. Direct fluorescent antibody testing and viral culture are less rapid but are standard tests that may help with the diagnosis. Direct fluorescent antibody testing can have a high false-negative rate, and viral cultures typically take 2 weeks for completion. These tests have largely been replaced by PCR analysis. Polymerase chain reaction has been the most sensitive test developed yet. With recent advances, real-time PCR, which can be performed within 1 hour in small hospital laboratories,15 has become more readily available and much more rapid than standard PCR. Further PCR testing can differentiate between the 2 possible infective strains (wild-type vs vaccine related).16 Real-time PCR is now commonly used as the first-line ancillary diagnostic test after physical examination.17


Although uncommon, HZ does occur in immunocompetent children and should be included in the differential diagnosis in children with vesicular lesions. Herpes zoster is a reactivation of VZV and initial exposure may be from the wild-type or vaccine-related strains. Clinicians must be vigilant in their evaluation of vesicular lesions in children even without known varicella exposure. Polymerase chain reaction testing can be helpful to distinguish between herpes simplex lesions and VZV. Polymerase chain reaction testing also may be of benefit to determine the strain of VZV infection.


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