This infant with a history of eczema, fever, irritability, malaise, and a disseminated monomorphic vesicular rash most likely has eczema herpeticum, for which the treatment is IV acyclovir.
Eczema herpeticum is caused by herpes simplex virus (HSV) in the setting of an impaired skin barrier (such as eczema). Although it can occur in any age group, this condition is particularly life-threatening in infants, who already have a weak immune system. Complications include herpes keratoconjunctivitis, herpes encephalitis, and viremia.
Durtschi and Fargo present a case in which an infant with a history of eczema presented with a vesicular rash. They show pictures of her presentation and discuss why eczema herpeticum is the correct diagnosis rather than impetigo, eczema vaccinatum, varicella, or contact dermatitis. Since ecezma herpeticum is a dermatologic emergency, it must be treated prior to laboratory confirmation.
Aronson et al. conducted a retrospective cohort study of 1150 children admitted to the hospital for ecezma herpeticum to assess the relationship between empiric antibiotics and outcomes. Many children receive empiric antibiotics as coverage in case a sumperimposed bacterial infection is present. The authors found no association between antibiotic treatment and length of hospital stay or mortality. If a child had a confirmed bloodstream infection, antibiotics were associated with a decreased length of stay.
Figure A shows an infant with eczema herpeticum. Illustration A shows an individual with impetigo. Illustration B shows an individual with bullous impetigo.
Answer 1: Varicella (chickenpox) can appear similar to eczema herpeticum, but is less likely in this child with no sick contacts and with a history of eczema. Varicella is also a multistage rash with papules, vesicles and crusting present at the same time. Treatment for varicella is supportive care (acyclovir for varicella is still being studied) and isolation to prevent spread of disease.
Answers 2 and 3: Although bacterial skin infections such as impetigo can appear similar to eczema herpeticum, they are generally less wide-spread, involve honey-colored crusting, and are more likely to have lesions in multiple stages (vesicles, macules,papules, crusting) (Illustration A). It can also have a bullous appearance (Illustration B).
Answer 4: In an infant with with a disseminated rash, oral acyclovir is inappropriate. Eczema herpeticum is a life threatening condition in an infant and requires IV treatment.
Durtschi HF, Fargo MV. Infant with vesicular rash. Am Fam Physician. 2010 May 1;81(9):1143.
PMID:20433131 (Link to Abstract)
Aronson PL, Yan AC, Mohamad Z, Mittal MK, Shah SS. Empiric antibiotics and outcomes of children hospitalized with eczema herpeticum. Pediatr Dermatol. 2013 Mar-Apr;30(2):207-14. doi: 10.1111/j.1525-1470.2012.01860.x. Epub 2012 Sep 20.
PMID:22994962 (Link to Abstract)