Erythema toxicum

Overview
Erythema toxicum is a very common rash in infants. It appears in up to half of newborns carried to term, usually between day 2-5 after birth.

Presentation
The rash is composed of small pustular lesions, each on a separate reddened base.

Diagnosis
At times the appearance can raise concern that the rash could be due to herpes simplex, however the latter generally has a more clustered and vesicular appearance.

In uncertain cases, a scraping of a lesion can be done and the fluid examined under the microscope. Herpes lesions will have a positive direct fluorescent antibody test. The fluid from erythema toxicum lesions will show many eosinophils.

Causes
The cause of erythema toxicum is unknown, but it is thought to be a benign condition that causes no discomfort to the infant and the rash will generally disappear spontaneously in about 2 weeks.