A Neonate With a Head-to-Toe Maculopapular Rash
During a newborn clinic visit, the parents of a 4-day-old girl expressed concerns about their daughter’s progressively spreading rash.
The white neonate had been born at 38 weeks of gestation to 28-year-old gravida 1, para 1 mother after an uncomplicated pregnancy and normal vaginal delivery. Maternal serologic test results were all negative, including for group B streptococcus, HIV, herpes simplex virus, and syphilis. No fetal abnormalities were detected on prenatal ultrasonograms.
The neonate’s birth weight was 3.2 kg and her length was 50 cm. She did well and was discharged from the hospital within 2 days. The girl had developed a rash while in the hospital, but it had been only a few spots on her trunk. Now, however, it involved her face and extremities. She continued to feed well and had no fever. The rest of her history was noncontributory.
On physical examination at presentation, the patient was vigorous, well hydrated, and in no acute distress. Her weight was 3.1 kg, and her vital signs were within normal limits. She had an erythematous, blanchable, maculopapular rash over her face, trunk, and extremities, but with no increased skin temperature or pus drainage from any lesions. The remaining physical examination findings were completely normal.
What is causing this 4-day-old girl’s extensive rash?
A. Erythema toxicum neonatorum
B. Transient neonatal pustular melanosis
A, erythema toxicum neonatorum
Erythema toxicum neonatorum (ETN) is a benign, self-limited condition that features multiple erythematous papules with an approximate diameter of 1 to 3 mm that progress rapidly to pustules on a swollen base.1
ETN occurs in 50% to 70% of full-term neonates but is rare in premature neonates and those weighing 2,500 g or more. The lesions typically appear within 24 to 48 hours of birth and are distributed over the trunk and extremities but spare the palms and soles. ETN lesions may localize at pressure sites.
Four types of lesions can occur: macules, wheals, papules, and pustules. Lesions resolve within 5 to 7 days without sequelae. New lesions might appear as old lesions resolve.1
ETN is diagnosed primarily on clinical examination, although it can be confirmed with a Wright-stained smear, with the contents of pustules showing numerous eosinophils and occasional neutrophils on microscopic examination.1
The etiology of ETN is unknown. There are numerous theories about the pathogenesis of ETN, the most widely accepted of which suggests that it is a cutaneous immunologic response to microbial colonization of hair follicles from the first day of life.2-4 This theory is based on the histologic observation of the presence of dense inflammatory infiltrates around hair follicles, consisting mostly of eosinophils, but also with neutrophils, macrophages, and dendritic cells, as well as the up-regulation of various inflammatory mediators such as interleukins 1 and 8, eotaxin, psoriasin, and nitric oxide synthases 1 through 3.2-4
Marchini and colleagues2 postulated that “skin appendages,” predominantly the hair follicles, act as an entry port for microbes, prompting a local and systemic inflammatory response. They arrived at this theory by identifying the colonizing microbes on the skin of a cohort of 1-day-old neonates with and without ETN, and then examining biopsies of typical ETN lesions with electron microscopy to identify microbes in the affected skin tissue. They also recorded each infant’s body temperature as a marker of systemic acute phase response. Within all ETN lesions, the researchers identified staphylococcal bacteria near or in the hair follicle epithelium, as well as cocci that had been internalized into recruited immune cells around the follicle. Infants with ETN also exhibited a significantly higher body temperature than those without the rash, indicating a systemic inflammatory response to infection or tissue damage.
These findings support the widely accepted theory that microbial colonization of hair follicles results in the immunologic response that correlates with ETN. The fact that ETN lesions tend to spare the palms and soles can be explained by the absence of pilosebaceous follicles in these areas.
ETN is a benign self-limiting condition that does not require treatment. Occasionally, it can be confused with other eruptions of the neonatal period, such as transient neonatal pustular melanosis, eosinophilic pustular folliculitis, incontinentia pigmenti, acropustulosis, milia, miliaria, and congenital cutaneous candidiasis.
Sharda Udassi, MD, is an associate professor in the Division of General Academic Pediatrics at the University of Florida College of Medicine in Gainesville.
Stephanie Marshall, MD, is a pediatric resident at the University of Florida College of Medicine.
Ratna Acharya MD, is an assistant professor in the Division of General Academic Pediatrics at the University of Florida College of Medicine.
Sanjeev Y. Tuli, MD, is a professor of pediatrics, associate chair for Clinical Affairs and Community Relations, and Chief of the Division of General Academic Pediatrics at the University of Florida College of Medicine.
1. Berg FJ, Solomon LM. Erythema neonatorum toxicum. Arch Dis Child. 1987;62(4):327-328.
2. Marchini G, Nelson A, Edner J, Lonne-Rahm S, Stavréus-Evers A, Hultenby K. Erythema toxicum neonatorum is an innate immune response to commensal microbes penetrated into the skin of the newborn infant. Pediatr Res. 2005;58(3):613-616.
3. Monteagudo B, Labandeira J, Cabanillas M, Acevedo A, Toribio J. Prospective study of erythema toxicum neonatorum: epidemiology and predisposing factors. Pediatr Dermatol. 2012;29(2):166-168.
4. Marchini G, Ståbi B, Kankes K, Lonne-Rahm S, Østergaard M, Nielsen S. AQP1 and AQP3, psoriasin, and nitric oxide synthases 1-3 are inflammatory mediators in erythema toxicum neonatorum. Pediatr Dermatol. 2003;20(5):377-384.