Rhymin’ pediatric dermatologist provides Demodex tips



This story appears courtesy of MDedge News


WAIKOLOA, HAWAII – Pediatric dermatologist Andrea L. Zaenglein, MD, has composed a whimsical couplet to help physicians broaden their differential diagnosis for acneiform rashes in children.

Pustules on noses: Think demodicosis!

The classic teaching has been that Demodex carriage and its pathologic clinical expression, demodicosis, are rare in children. Not so, Dr. Zaenglein asserted at the Hawaii Dermatology Seminar provided by Global Academy for Medical Education/Skin Disease Education Foundation.

“One of the things that we never used to see in kids but now I see all the time, probably because I’m looking for it, is Demodex. You’re not born with Demodex. Your carriage rate will increase over the years and by the time you’re elderly, 95% of us will have it – but not me. I just decided I’m not having these. I’m not looking for them, and I don’t want to know if they’re there,” she quipped, referring to the creepiness factor surrounding these facial parasitic mites invisible to the naked eye.

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The mites live in pilosebaceous units. In animals, the disease is called mange. In humans, demodicosis is caused by two species of mites: Demodex folliculorum and D. brevis. The diagnosis is made by microscopic examination of mineral oil skin scrapings.

Primary demodicosis can take the form of pityriasis folliculorum, also known as spinulate demodicosis, papulopustular perioral, periauricular, or periorbital demodicosis, or a nodulocystic/conglobate version.

More commonly, however, Demodex is a secondary player in pediatric acneiform rashes, including periorbital dermatitis, steroid dermatitis, midchildhood acne, and rosacea.

“Demodicosis can be associated with immunosuppression. Kids with Langerhans cell histiocytosis seem to be prone to it. But you can see it in kids who don’t have any underlying immunosuppression, and I think there are more and more cases of that as we go looking for it,” said Dr. Zaenglein, professor of dermatology and pediatrics at Penn State University, Hershey, and immediate past president of the Society for Pediatric Dermatology.

Look for Demodex in children with somewhat atypical versions of common acneiform eruptions: for example, the ‘pustules on noses’ variant.

“Finding Demodex can alter your treatment and make it easier in these cases,” she said.

Metronidazole and ivermectin are the systemic treatment options for pediatric demodicosis.

“I tend to use topical permethrin, just because it’s easy to get. I’ll treat them once a week for 3 weeks in a row. But also make sure to treat the underlying primary inflammatory disorder,” the pediatric dermatologist advised.

Other topical options include ivermectin cream, crotamiton cream, metronidazole gel, and salicylic acid cream.

Dr. Zaenglein reported having financial relationships with Sun Pharmaceuticals, Allergan, and Ortho Dermatologics.

SDEF/Global Academy for Medical Education and MDedge are owned by the same parent company.

By Bruce Jancin
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