Onychomycosis in children difficult to treat without proper diagnosis

Key Points

Chicago - Pediatric onychomycosis is relatively uncommon, with an overall prevalence among all patients with onychomycosis of about 2.5 percent. The condition occurs more often in adolescents than in young children, says Amy Paller, M.D., Walter J. Hamlin Professor, chairwoman of dermatology, professor of pediatrics, Northwestern University Feinberg School of Medicine, Chicago.

The relatively infrequent occurrence of onychomycosis in younger children contributes to physicians' difficulties in diagnosing the problem. When the condition occurs in children, she says, there is usually an identifiable exposure.

"We're usually talking about toenails, dermatophytes such as Trichophyton mentagrophytes or T. rubrum, and associated tinea pedis," Dr. Paller says. "Candida generally occurs in fingernails because of wet work, and that doesn't often occur in children, except in babies or toddlers who develop thrush and pass it onto fingers (or sometimes toes if flexible) from sucking. With recurrent or difficult-to-treat candidal onychomycosis in children, we should always be thinking about the possibility of immune suppression," she says.

Difficult diagnosis

Dr. Paller says it may be a bit more difficult for physicians to diagnose onychomycosis in the pediatric population, because it is typically not the first option that comes to mind.

"There are a variety of reasons you can have nail dystrophy: anything from trauma, which is really common in kids and more likely leads to a single affected nail, to psoriasis, which in my practice leads to the greatest confusion," she says. "Nail dystrophy that can resemble onychomycosis can also result from other inflammatory skin disorders, such as hand or foot eczema, and in association with genetic diseases such as pachyonychia congenita."

Even if a patient is known to suffer from a recognized nail disorder such as psoriasis, it should be recognized that secondary dermatophyte infection can occur in the abnormal nail, according to Dr. Paller.

"The existence of psoriasis doesn't prove nail fungus isn't present," she says. "Now, if multiple nails are similarly involved, it is more likely to have a more systemic cause alone such as psoriasis."

Dr. Paller explains that too often, onychomycosis doesn't get the consideration it should. People have the tendency to write it off as a potential diagnosis, because the child is pre-pubertal. But diagnosing the condition isn't difficult, she says. It can be done with KOH analysis or cultures, but Dr. Paller reports that studies have shown KOH to be more sensitive. Pathologists can also look at nail clippings for signs of fungus through special stains.