Onychomycosis in the US Pediatric Population-An Emphasis on Fusarium Onychomycosis.

Background: Onychomycosis is a common nail disease that is often difficult to treat with a high risk of recurrence.

Objective: To update our current understanding of the etiologic profile in pediatric patients with onychomycosis utilizing molecular diagnosis by polymerase chain reaction (PCR) combined with histopathologic examination.

Methods: Records of 19,770 unique pediatric patients were retrieved from a single diagnostic laboratory in the United States spanning over a 9-year period (March 2015 to April 2024). This cohort represents patients clinically suspected of onychomycosis seen by dermatologists and podiatrists. Dermatophytes, nondermatophyte molds (NDMs), and yeasts were identified by multiplex real-time PCR corroborated by the demonstration of fungal invasion on histopathology.

Results: An average of 37.0% of all patients sampled were mycology-confirmed to have onychomycosis. Most patients were between ages 11 and 16 years, and the rate of mycologically confirmed onychomycosis was significantly higher among the 6- to 8-year (47.2%) and 9- to 11-year (42.7%) age groups compared to the 0- to 5-year (33.1%), 12- to 14-year (33.2%), and 15- to 17-year (36.7%) age groups. The majority of infections were caused dermatophytes (74.7%) followed by NDMs (17.4%). The Trichophyton rubrum complex represents the dominant pathogen with higher detection rates in the 6- to 11-year-olds. Fusarium was the most commonly isolated NDM with an increasing prevalence with age.

Conclusions: Elementary school-aged children have a higher risk of contracting onychomycosis which may be attributed to the onset of hyperhidrosis at puberty, use of occlusive footwear, nail unit trauma, and walking barefoot. Fusarium onychomycosis may be more prevalent than expected, and this may merit consideration of management strategies.