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Erythema Toxicum Neonatorum

What is Erythema Toxicum Neonatorum?


Erythema toxicum neonatorum (ETN), also known as erythema toxicum and toxic erythema of the newborn, is a very common skin lesion that appear on a newborn infant in the first week of life. It was first described by Barthalomaeus Netlinger in 1472 and renamed by Leiner as Erythema neonatorum toxicum in 1912.

Lesions are present not at birth but usually within 12 to 48 hours after birth, and a delayed onset of ETN is sometimes also observed. The lesions, which are benign, may be found scattered anywhere on the body but more commonly in the face and trunk. ETN is a self-limited eruption that resolve spontaneously. It occurs approximately 50 to 70 percent of all full-term newborns but rarely in premature infants or in babies weighing less than 2.5 kilograms. There is no racial or sexual predilection, but there is an increased frequency among infants with increased birth weight and gestational age. Recurrence has been reported during the first two weeks.

Diagnostic exams which involve microscopic examination using a Gram stain or Wright stain will reveal predominance of eosinophils. A smear of central vesiculopustular lesion stained by Wright stain demonstrates numerous eosinophils.

Tsanck smear or fluorescent antibody testing consists of removing the blister roof and preparing a slide from scrapings of the base of the blister using a scalpel blade. This is to determine if it is herpes simplex or ETN.

Skin biopsy may sometimes be needed to rule out other more serious diseases. Lesional skin biopsy obtained for routine histopathology examination reveals subcorneal intraepidermal blistering with the blister cavity filled predominantly with eosinophils. Bacterial cultures of these pustules invariably result in negative findings.

Differential diagnosis includes Herpes simplex virus infection, impetigo, listeria infection, neonatal sepsis, and varicella.

Symptoms of Erythema Toxicum


There are four kinds of localized lesions: macules, wheals, papules, and pustules. They first appeared on the face and then spread to the trunk, proximal extremities, and buttocks. The lesions are generally characterized as a rash, usually small (less than 3mm.), pale yellow papules which may be surrounded by erythematous wheal. The lesion appearance is similar to a “flea bite.” Central vesicle may contain numerous eosinophil, and peripheral blood contains eosinophilia up to 20 percent.

Histologically, the pustules are most often located in the epidermis just beneath the stratum corneum and are filled with eosinophils. Histological examination of a macule usually shows a perivascular infiltrate composed primarily of eosinophils and a few polymorphonuclear leucocytes and mononuclear cells.

Erythema toxicum can be confused with herpes simplex infection, impetigo, or miliaria rubra (heat rash). Herpes simplex lesions, which is usually caused by the vertical transmission from mother to newborn, tend to have a more vesicular appearance rather than pustular. Impetigo usually has more developed pustular lesions and can be differentiated based on Gram stain performed on intralesional contents. Presence of neutrophils on Wright stain or presence of organisms on Grain stain is suggestive of bacterial impetigo. Diagnosis of miliaria rubra typically follows from a history of excessive warming, either from occlusive clothing or from an incubator. Lesions are usually more confluent than those seen in erythema toxicum and demonstrate lymphocytic infiltrate on Wright stain.

Usually these lesions are temporary, for they appear during the first or second day after birth and disappear after one week. Full-term newborns who weigh greater than 2.5 kilograms are more likely to show rashes. New lesions appear as old ones resolve.

Causes of Erythema Toxicum

The medical condition has been considered idiopathic for the causes of erythema toxicum have not yet been established. Presently, there are several unproven etiological hypotheses, including skin reaction to absorbed enterotoxines, hence the name “toxicum,” an allergic reaction due to eosinophilia in the lesions (and in the peripheral blood of some patients); however, an allergic agent (e.g., detergent soap) or allergens in bedding and clothing have not yet been identified. Transient adjustment of the newborn’s skin to mechanical/thermal stimuli, a decrease in corticosteroid blood levels following neonatal stress enhancing the eosinophilic response, maternofetal transfer of lymphocytes prior to, or during, delivery causing a minor transient form of acute GvH reaction, and activation of skin antimicrobial system before birth and strengthened in the first few days of life, all have also postulated as factors causing this acute inflammatory response.


Because erythema toxicum is a self-limiting skin eruption, no specific treatment is required. When the eruption, which resemble erythema toxicum, presents in a newborn, it is necessary to consider the differential diagnosis and to rule out other potentially serious vesiculopustular dermatoses of neonates that can mimic erythema toxicum clinically.


There are no reported complications of erythema toxicum. It is only transient and benign, and it remains for a brief duration and resolves spontaneously. Post-inflammatory hyperpigmentation may follow but resolves within weeks to months.

Erythema Neonatorum Pictures

Erythema Toxicum Neonatorum images

Erythema Toxicum Neonatorum

Erythema Toxicum Neonatorum

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