Erythema Toxicum Neonatorum

Erythema toxicum neonatorum (ETN) is a very common, benign condition. Originally described by Netlinger in 1472, it was known as “toxic erythema of the newborn” and was renamed erythema toxicum neonatorum by Leiner in 1912[1]. ETN occurs in approximately half of full-term neonates, possibly favoring those delivered vaginally, and is only rarely seen in premature infants or those weighing less than 2500 g2,3 . It is most commonly observed in infants with Fitzpatrick types I-II skin, although this may be related to the difficulty in perceiving erythema in infants with darker skin, and may be more prevalent in males[3,4]. Rarely presenting at birth, ETN usually begins 24 to 48 hours after delivery, followed by a waxing and waning course over the next few days.

Although the onset may be as late as 1–2 weeks of age, additional diagnoses need to be considered in these cases. Five distinct components may be present in various combinations: erythematous macules, wheals, and small papules, vesicles and pustules, usually measuring 1–2 mm. The characteristic central papule with a surrounding erythematous flare is reminiscent of a flea bite . Mechanical irritation may precipitate new lesions .