Fifth Disease. Toddler with the classic slapped-cheek appearance of fifth disease caused by parvovirus B19. Note the lacy reticular macular rash on the shoulder and upper extremity. (Photo contributor: Anne W. Lucky, MD.)
Erythema toxicum neonatorum is a benign, self-limited vesicopustular lesion of unknown etiology that occurs in up to 70% of term newborns. It is characterized by discrete, small, irregular erythematous macules or patches up to 2 to 3 cm in diameter with 1- to 3-mm firm pale yellow or white papules or pustules in the center. The trunk and proximal extremities are predominantly involved, but lesions can appear diffusely, only sparing the palms and soles. This rash usually appears within the first 24 to 72 hours of life but may be present at birth. The distinctive feature of erythema toxicum is its evanescence, with each individual lesion usually disappearing within 5 to 7 days. New lesions may occur in a waxing and waning fashion. The diagnosis is usually made based on the clinical appearance of the rash in an otherwise well-appearing neonate without any systemic signs of illness. Wright-stained slide preparations of a scraping from the center of the lesion demonstrate numerous eosinophils. Cultures from these lesions will be negative. The differential diagnosis includes neonatal acne, transient neonatal pustular melanosis, newborn milia, miliaria, infantile acropustulosis, neonatal herpes simplex, bacterial folliculitis, candidiasis, incontinetia pigmenti, and impetigo of the newborn.
Erythema Toxicum. Newborn infant with diffuse macular rash of erythema toxicum. (Photo contributor: Kevin J. Knoop, MD, MS.)
Management and Disposition
No specific therapy is indicated in the setting of a well-appearing newborn with normal activity and appetite. Parents should be educated and reassured about the evanescence of the rash. In cases where impetigo, Candida, or herpes infections are suspected, a smear from the center of the lesion and bacterial and viral cultures may be necessary to make a final diagnosis.
Erythema toxicum neonatorum is the most common newborn rash.
The lesions may present anywhere on the body but tend to spare the palms and soles.
Laboratory evaluation is unnecessary.
Erythema Toxicum. Close-up of lower extremity of a neonate with erythema toxicum. (Photo contributor: Robert W. Hickey, MD.)