SAN FRANCISCO Consider infectious causes first when evaluating blisters and pustules in a newborn, advised Ilona J. Frieden, MD, at the American Academy of Dermatology meeting here.
"We think of infectious causes first because they are the ones that can kill," said Frieden. "Next I think of transient causes, which are more common to this age group. Finally, I consider rare causes, which comprise an ever-expanding group of disorders." Frieden is associate clinical professor of pediatric dermatology at the University of California-San Francisco.
"I try to be inclusive because ulcerations could have started as blisters, and pustules could have started as vesicles," Frieden said. Vesicles, bullae and pustules are all primary skin lesions, which develop as a result of the intrinsic nature of the disease process that causes them. Erosions, ulcerations and crusts are secondary skin lesions, which evolve from primary skin lesions.
Primary and secondary skin lesions may be present simultaneously, leading to an overlap in skin morphology. Vesicles can evolve into pustules or bullae and pustules can rupture, leaving eroded or crusted areas of skin. Despite this potential for overlap, Frieden said, many conditions will have one predominant morphology and this may help narrow the scope of the differential diagnosis.
To evaluate a baby with one of these conditions, Frieden recommended a Tzanck test, potassium hydroxide (KOH), Gram's stains, cultures and a skin biopsy, depending on the morphology. "Unfortunately, sometimes you have to be selective and really think through your differential diagnosis before you whip out your scalpel," said Frieden, "because you may only have one or two lesions to work with, so you need to prioritize."
Staphylococcus aureus is the most common infectious cause of lesions in infants. They proliferate in the diaper and umbilical areas. Often there is a staph carrier in the nursery resulting in the neonate's condition. Onset is usually days to weeks. "One sees vesicles, pustules, or classic bullous impetigo," Frieden said.
The diagnosis can be made with Gram's stain and or culture, and Frieden said these babies should be treated with systemic antibiotics rather than topical antibiotics because she considers newborns to be "relatively immunocompromised hosts."
Listeria monocytogenes are another possible infectious cause of blisters and pustules in a newborn. Frieden worries about this in cases where the baby is sick at birth and has widespread hemorrhagic pustular eruptions.
In these cases, the mothers are infected and pass on a systemic form of infection to the baby. These babies are often premature with widespread pustules because the Listeria induces early labor. "You can do a Gram's stain on these pustules and find gram-positive rods," said Frieden. These cases have a high mortality rate even with prompt recognition and treatment, she said.
Pseudomonas infection can occur later in the newborn period in babies who have had intestinal surgery and/or who have been repeat patients in the neonatal intensive care unit. This type of infection often will occur around the diaper area.
"One has to think about doing blood cultures and looking for septicemia and treating these children systemically," said Frieden. The course of treatment would depend on the hospital's protocol and the patient's sensitivity, but would probably be a semi-synthetic penicillin plus an amino glycoside or a third-generation cephalosporin, according to Frieden.
Congenital or acquired candidiasis, herpes simplex virus (HSV), aspergillus and scabies are other infectious causes of blisters and pustules in a newborn.
Erythema toxicum neonatorum, neonatal pustular melanosis, miliaria and neonatal acne are examples of sporadic or transient causes of blister and pustule-type lesions in newborns. Uncommon or rare causes include acropustulosis of infancy, congenital self-healing Langerhans' cell histiocytosis, incontinentia pigmenti and eosinophilic pustular folliculitis.
According to Frieden, widespread blistering always requires a biopsy. Some causes of widespread blistering include staphylococcal scalded skin syndrome (SSSS), congenital HSV, epidermolysis bullosa (EB), epidermolytic hyperkeratosis, bullous mastocytosis and toxic epidermal necrolysis.
Recommended initial wound care management includes puncturing tense blisters, covering denuded areas with bacitracin and wrapping with sterile petrolatum-impregnated gauze.
Frieden pointed out that it is important to remember that a baby who is born with a pustule might have had a blister in utero. In addition to considering all of the information gathered in a thorough patient history, past medical history and the mother's medical history should be considered. History of maternal illnesses or medications during pregnancy, history of maternal fever during delivery, number of hours of ruptured amniotic membranes and the method of delivery should all be noted, Frieden said.
Other specific aspects of the pregnancy itself may provide clues for diagnosis. A history of fever and the onset of a genital rash suggest the possibility of a primary episode of HSV infection, which greatly increases the neonate's risk of acquiring herpes. A history of maternal fever and fetal tachycardia during labor may indicate chorioamnionitis and infection with agents such as Listeria monocytogenes or group B Streptococcus. The presence of a genital foreign body such as an intrauterine device or a cervical suture increases the risk of congenital candidiasis. A history of primary varicella in the peripartum period may result in neonatal varicella in the newborn.
Frieden pointed out that skin changes at birth may reflect evolution of the skin lesions in utero. The newborn who presents at birth with erosions or crusts could still have a blistering disease because blisters or pustules may have occurred in utero.
For more information:
- Frieden IJ. Dermatology in the newborn nursery. Presented at the American Academy of Dermatology meeting. March 21-26. San Francisco.
- Boiko S. Diapers and diaper rash. Dermatology Nursing 1997;9:33-70.
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