National report ? Most babies and toddlers presenting with a rash on the buttocks, genitalia, lower stomach or upper thighs have contact dermatitis. But occasionally, there's a zebra lurking under the diapers.
"If the rash is persistent for months on end," says Bernard A. Cohen, M.D., "dermatologists need to keep alternatives in mind. Occasionally, it's evidence of a primary dermatological condition or of an underlying systemic disorder."
He advises, "Look for clues outside the diaper area. Ask about the baby's general health, whether it is thriving or not, and determine if it is at or above normal growth parameters."
Dr. Cohen, who is director of pediatric dermatology at Johns Hopkins Medical School in Baltimore, says seborrheic dermatitis may appear when the child is as young as 3 to 4 weeks and persist for months. If the lesions last longer or if the child shows no sign of itchiness, the problem may be infantile psoriasis.
Other autoimmune diseases to watch out for, he says, are lichen sclerosis, linear IgA bullous dermatosis, epidermolysis bullosa acquisita and bullous pemphigoid.
Dr. Cohen says immunobullous conditions are uncommon but do show up in dermatological practices as blisters or erosions. He advises taking a biopsy to confirm a diagnosis.
"Inflammatory bowel disease can also masquerade as a diaper rash," Dr. Cohen notes. "Again, it's not very common, but may present as lumps or bumps in the diaper area."
Langerhans cell histiocytosis is another possibility, manifesting with crusty, weepy lesions that can bleed.
Dr. Cohen advises: Be on the alert for undiagnosed cystic fibrosis and nutritional disorders, such as zinc deficiency dermatitis-acrodermatitis enteropathica, zinc-deficient breast milk, biotin deficiency, biotinidase deficiency, glucagonoma, citrullinemia, malnutrition, malabsorption-liver disease, short gut syndrome and essential fatty acid deficiency.
The diaper end
In general, however, most dermatitis is diaper-related. In the 1960s, diapers evolved from a double layer of cotton folded into a triangle and attached with safety pins to a commercial product that included a top sheet of plastic and a cellulose pulp core. In recent decades, manufacturers changed the core to a gel material capable of absorbing 80 times its weight in fluids.
The dermatologist says, "The gel prevents the skin from becoming super-hydrated, so the incidence of diaper rash has been on the decline."
Diapers as a cause of irritant dermatitis was first described in 1905. For decades, it constituted a significant portion of dermatology consults in children under the age of 5. The condition typically presents at 2 weeks to 18 months and peaks at 6 months to 9 months. Of note: Breast-fed infants have a lower incidence of dermatitis.
In most cases, the diaper itself is the cause. Be sure caregivers are using superabsorbent brands, Dr. Cohen advises. If they already are, ask them to switch brands.
Feces and/or urine can cause dermatitis. An increase in pH activates fecal lipases and proteases, increasing bacterial and fungal counts, which in turn break down the skin barrier, causing a rash to erupt. Candida albicans is often implicated in severe cases of dermatitis. A very recent multi-center, open-label study demonstrated topical ciclopirox (0.77 percent) to be safe and effective for these cases.
Caregivers may be failing to change diapers with sufficient frequency, or a baby could have persistent diarrhea. If the latter, Dr. Cohen advises, determine the cause (i.e., malabsorption, viral gastroenteritis, antibiotics, metabolic disorder, drugs, diet) and treat it appropriately. In treating dermatitis, avoid high-potency topical steroids and combination products, he says, and minimize the duration of use and the frequency of application.